How do you measure time on a tidelocked planet?

[Aotrs Commander]

It's difficult to to know to put this question, so the for the sake of argument, I've put it here.

This is both a biomechanical and sociological question.

There is a planet. It orbits around a large star whose goldilocks zone is significantly far from the star that the orbit is measured in thousands of Earth-years1. The planet is tide-locked2. The planet is otherwise the same size and atmospheric content as Earth, but the life that developed is entirely alien.

So. Because the world is tide-locked, there is no day/night cycle and there are no seasons (the orbit cannot be erratic). So you can't measure time by the sun or the stars. In any case, as the plant remains largely habitable by the stabilising feedback of clould cover, the sky isn't always readily visible (and it's often raining). At ground level, there is a continuous stiff breeze coming from the dark side to the light side (again, part of the researched climatic conditons).

So how do you measure time, if you are a plant or a creature or a primitive neolithic tribe?

(Civilisations might make their own measures - I'd have to research into the history of who "invented" hours/minutes/seconds, but the larger question is more fundamental.)

This question arises as I contemplate, as I do on and off, a campign game in which the PCs are part of a neolithic tribe, who are forced on a migration by changing geological conditions. As I was thinking about it today about the mechanics of it, I considered "well, you could simplify food to be 1 unit per person per day, maybe half for young children under... five... Wait, hang on. How long is a 'day?' For that matter, how do you measure what's a 'young child?' How long, even, is a guard duty shift going to be...?"

This is a rather metric defining question, the more I think about it.

Athe most basic level, how does a plant know when to flower or seed? If it doesn't rely on insect-analgoue pollination, how do plants seed? They can't reliably use wind, since it for the majority only goes in one direction. Rhisomes are one obvious answer, but the other might be as interesting as like the Earth plants which shoot their seeds. But even then - what is the interval? In terrestrial jungles where there are no real seasons, trees of different species fruit at seemingly arbitrary periods, but even there, there is a day/night cycle to work off.

What is an animal's activity cycle going to be like? Again, on Earth, where there are places were day and night are both very long, they do change over. (I'm not even sure how long/when polar creatures sleep during the summer). Logically, one would assume that such creatures to have an functionally cathemerial cycle (i.e. for animals that vare active during both day and night), but even those are subject to the circadian rhythm which is absent here, so what instead defines the period?

For a primitive tribe, how would their society have developed to tell the passage of time? How often do they need to eat, when the basis is not a 24-hour circadian cycle? How do you tell how old someone is (and thus when they reach maturity)? Is there a specialias jon, like a time-keeper in the village whose sole job it is to measure time and how?

This is a very difficult question for me to answer, to the point I'm not even sure where to start looking. Thus, as inspiration (rare these days) has struck me to think about it, I have asked in a few places to see if anyone can offer any suggestions.



Now, in my earlier contemplation of this question, I did make one concession. There is a moon, a relatively late capture. This orbits once every six Earth-days, but though it appears about the same size in the sky as Luna to Earth, it's very small and low mass. (Tides is a difficult question, though it appears to impart about 94% of the acceleration Luna imparts to Earth, due to it's speed. It is assumed to be partly why the planet is not 100% completely tide-locked.) But that's nowhere near fundamental enough for the biology side of the question and aside from potential tides, the moon again won't be readily visible for an easy count even for a civilisation.



I can, of course, elaborate in more detail about the set-up, but I have tried to keep this down to the minimum required boundary conditions, else the question would likely be lost amid the rest of it.




1There is a long and complicated explanation (in involved a lot of astrophysics maths, among other things) as to the set-up, but I have omitted it here for breivty and relevance to the question at hand.

2Strictly speaking, it's ins't 100%, but the day length is also in thousands of Earth-years at a minimum.

[a_flemish_guy]

seasons could be measured in how long it takes for crops to grow in
semi-nomadic herdsmen often sewed crops and moved on and came back when it was time for the harvest

an hour could be measured in the time it takes for a campfire to need new logs, later on candles could be used for more accurate measurements, even later things like waterclocks could be introduced

so people's ages would be recorded in seasons and activities would be measured in hours

sleep comes naturally after a while so days could be measured by the times you've slept (if you want to say a week from now then you'd say after we slept for 7 times), it'd be hard to accuratly pinpoint this however so this method can only be used if you live close to the person you're dealing with (edit: just saw your post about the moon, so yeah, weeks are 6 days and are depended on which stance the moon is in)

overall, quite an interesting question, need to think more about this

[King of Nowhere]

well, quite an interesting conundrum. I also assume that there are no satellites of the planet to give a natural clock



So how do you measure time, if you are a plant or a creature or a primitive neolithic tribe?


i'd say that you probably don't measure time at all. after all, measuring time is something needed in a planet where stuff is changing.
a plant certainly does not measure time. a plant on earth may measure time to ensure to release seeds in spring, so that they will find favorable growing conditions in the earliest, most vulnerable part of its life. but in a planet without season, why bother? a plant would release seed whenever it's ready.




(Civilisations might make their own measures - I'd have to research into the history of who "invented" hours/minutes/seconds, but the larger question is more fundamental.)

This question arises as I contemplate, as I do on and off, a campign game in which the PCs are part of a neolithic tribe, who are forced on a migration by changing geological conditions. As I was thinking about it today about the mechanics of it, I considered "well, you could simplify food to be 1 unit per person per day, maybe half for young children under... five... Wait, hang on. How long is a 'day?' For that matter, how do you measure what's a 'young child?' How long, even, is a guard duty shift going to be...?"


our culture depends on time, but i'd say a culture growing on that planet would develop differently from us. time is important for us, it probably wouldn't be for them. not until the industrial revolution, when you need to have everyone come to the factory at the same time to work. for an ancient society where people work mostly alone, if you work in your field while your neighboor is sleeping, does it matter? in our world people started working at dawn because they needed light to see, but in your case they have light all the time.
and there's going to be some advantages. you don't need a night guard or something, because there is always someone awake at any time.

people eat when they are hungry. sleep when they are tired. a young child is one who's in a certain phase of physical development. those are easy questions. how long are guard duty, or any other duties, they are likely to eyeball it. and there would be no guard duty because everyone sleeps differently.

or maybe a tribe would syncronize their rythm - they do need to walk together when moving, after all; hunter gatherers need to act together - just by consensus, or by leadership.
consensus: when enough people are awake, they wake up the others. when enough people go to sleep, the others follow.
leadership: when the chief goes to sleep, everybody does. when the chief wakes up, everybody does.





This is a rather metric defining question, the more I think about it.

Athe most basic level, how does a plant know when to flower or seed?

when they reached maturity and have gathered enough nutrient storages needed to produce seed. time is irrelevant. it's not like they have to wait spring to give their seed the highest chance of survival.





If it doesn't rely on insect-analgoue pollination, how do plants seed? They can't reliably use wind, since it for the majority only goes in one direction. Rhisomes are one obvious answer, but the other might be as interesting as like the Earth plants which shoot their seeds.


fruits are the easy answer. an animal eats them and carries the seed in every direction.
fruits are quite complex evolutionary, and ancient plants would not have them available.
you can also make seeds extra light so that they can fly on winds long enough to get raised and moved towards the night side (because the wind can't just blow in one directon forever. i assume in the higher atmosphere the wind blows in the opposite direction, forming a convection cell).
but yes, rhisomes are the easy answer.
making long limbs that drop heavy seeds may also be viable.
shooting seeds doesn't seem very effective; how far could they go?


But even then - what is the interval? In terrestrial jungles where there are no real seasons, trees of different species fruit at seemingly arbitrary periods, but even there, there is a day/night cycle to work off.

why would there even be an interval? we rely on time because on our planet we have reasons to do things at certain times, because some times are more favorable than others. in a planet where time is not relevant, the question wouldn't even make sense. that neolithic tribe may not even have a word for time, not on larger intervals. it certanly would not have words for days, weeks, years.





What is an animal's activity cycle going to be like? Again, on Earth, where there are places were day and night are both very long, they do change over. (I'm not even sure how long/when polar creatures sleep during the summer). Logically, one would assume that such creatures to have an functionally cathemerial cycle (i.e. for animals that vare active during both day and night), but even those are subject to the circadian rhythm which is absent here, so what instead defines the period?

creatures have a biological clock inside them. like, put you in a closed room, and you still have a rough idea of how much time has passed.
but it's not accurate. nor does it need to be. why would animals even have a circadian cycle in a planet without a day?




For a primitive tribe, how would their society have developed to tell the passage of time?

for short time intervals; when you get hungry, when you need to pee, that sort of stuff. for longer times: when grandfather was young, before you were born. not that they'd be used often, because there's no reason to refer to long time intervals; maybe reserved for mythology.


How often do they need to eat, when the basis is not a 24-hour circadian cycle? How do you tell how old someone is (and thus when they reach maturity)? Is there a specialias jon, like a time-keeper in the village whose sole job it is to measure time and how?

you are still thinking in modern terms, where we make so much fuss about time - mostly because we depend on objective measures.
people do need to eat when they get hungry. if you were locked into a closed room with no clocks, would you be like "omg I don't know when I have to eat"? nope; at some point you'd grow hungry, and you'd eat. then you would not be hungry for another while.
and you certainly do not need a calendar to tell the difference between a child, a kid, a young adult, a mature adult, etc. in fact, even as late as the middle ages most people didn't knew the year they were born with precision. it just was not important. as for telling when someone is an adult, our society set 18 years old because we need an exactly written law. in ancient societies, mostly women were married as soon as adult - could be anywhere between 12 and 16 years of age, because they had to make children as soon as possible to compensate for a mortality rate that's inconceivable for modern standards. and males would have to undergo some sort of passage ritual, generally a show of strenght and bravery. and yes, without a calendar somebody would undertake that ritual when equivalent to 16 earth years, someone when 20, but again, does it matter for society? the important thing is that when that kid looks grown enough, we send him out to kill a lion, or to put his hand into a bowl of bullet ants, or whatever they use as ritual. and then the guy is an adult.

as for somebody whose job is to keep passge of time... it's not impossible, but my gut says they wouldn't even conceive passage of time as we do. they do not experience progress like we do. therefore, they wouldn't see time as a past and future. they'd see it as a static thing, where nothing ever changes really. there is the tribe, and before i was born there was the tribe, and after i'll die there will still be the tribe, and why should i care about the passage of time if nothing ever really changes?




This is a very difficult question for me to answer, to the point I'm not even sure where to start looking. Thus, as inspiration (rare these days) has struck me to think about it, I have asked in a few places to see if anyone can offer any suggestions.



Now, in my earlier contemplation of this question, I did make one concession. There is a moon, a relatively late capture. This orbits once every six Earth-days, but though it appears about the same size in the sky as Luna to Earth, it's very small and low mass. (Tides is a difficult question, though it appears to impart about 94% of the acceleration Luna imparts to Earth, due to it's speed. It is assumed to be partly why the planet is not 100% completely tide-locked.) But that's nowhere near fundamental enough for the biology side of the question and aside from potential tides, the moon again won't be readily visible for an easy count even for a civilisation.


ok, i missed that part earlier. so they will have "weeks", after all. could be useful to measure time in the middle ranges, like "to reach the pastures to the east, we have to march for two weeks". but it wouldn't be a big part of people's life.

it can be hard, but you have to get out of modern scientific accurate mentality to understand neolithics tribes.
once an anthropologist visiting such tribes in the real world asked how far was the nearest village, he was told "two rice cookings". as in, start walking, and in twice the time it takes to cook rice, you'll be there. this is also something that they could do on your planet.
and it's a terrible measure for us; it depends on whether you like your rice hard or soft, how fast you walk... but it's good enough for a society that does not have to wake up at 7 am sharp to take the bus.

[Palanan]

Originally Posted by Aotrs Commander
So you can't measure time by the sun or the stars.

Even if the planet is tide-locked, that only affects its own rotation; it continues orbiting around the star, and thus its view of more distant stars is constantly changing.

That will establish the planet’s year—but if that’s thousands of our years, then you’ll need another metric. If there are other planets in the system, their motions will help establishing a cycle.

Note also that a larger planet is likely to have a number of larger moons, and their motions would be complex but predictable, in the same way that we can measure the 4:2:1 resonance of orbital periods for the inner three Galilean satellites of Jupiter.


Originally Posted by Aotrs Commander
In terrestrial jungles where there are no real seasons, trees of different species fruit at seemingly arbitrary periods….

Not arbitrary at all. Equatorial forests do have seasons, just not ones involving snow. Often there’s a wet season and a much, much wetter season, and note also complexities such as ENSO. Also, the day/night ratio is key. Fruiting seasons are not arbitrary in the least; fruiting is metabolically expensive, and obviously vital to the plant’s reproduction, so its timing is carefully regulated.


Originally Posted by Aotrs Commander
There is a long and complicated explanation (in involved a lot of astrophysics maths, among other things)….

I’d be very interested in seeing more of this. My only sense of tidally locked planets is the born-of-a-red-dwarf variety, so I’m wondering how this is possible at +500 AU, or whatever distance you’re using.

Also, is there a real-world example you’re basing this on? And how is this planet warm enough to support vertebrate-analogue life?


Originally Posted by King of Nowhere
I also assume that there are no satellites of the planet to give a natural clock

Please note the OP’s thirteenth paragraph, which describes the planet's moon in some detail.


Originally Posted by King of Nowhere
once an anthropologist visiting such tribes in the real world asked how far was the nearest village, he was told "two rice cookings".

This sounds highly suspect and likely apocryphal. Do you have a citation?

[Aotrs Commander]

well, quite an interesting conundrum. I also assume that there are no satellites of the planet to give a natural clock


i'd say that you probably don't measure time at all. after all, measuring time is something needed in a planet where stuff is changing.
a plant certainly does not measure time. a plant on earth may measure time to ensure to release seeds in spring, so that they will find favorable growing conditions in the earliest, most vulnerable part of its life. but in a planet without season, why bother? a plant would release seed whenever it's ready.


our culture depends on time, but i'd say a culture growing on that planet would develop differently from us. time is important for us, it probably wouldn't be for them. not until the industrial revolution, when you need to have everyone come to the factory at the same time to work. for an ancient society where people work mostly alone, if you work in your field while your neighboor is sleeping, does it matter? in our world people started working at dawn because they needed light to see, but in your case they have light all the time.
and there's going to be some advantages. you don't need a night guard or something, because there is always someone awake at any time.

people eat when they are hungry. sleep when they are tired. a young child is one who's in a certain phase of physical development. those are easy questions. how long are guard duty, or any other duties, they are likely to eyeball it. and there would be no guard duty because everyone sleeps differently.

These are good points (I've not quoted everything) and simialr has been suggested on the other place - but here, at least, there are some interesting mechanical constraints to worry about. Specifically, if the PCs are leading a tribe and are resposnible for managing the resources... How do I track the usage and consumption of resources? As I said, it's fine to simply say "each tribesperson needs 1 food and 1 water per" but the problem now becomes how to determine what per what. Distance might be partly one answer, but then how do you measure it if they stop?

(Small stuff like durations of effects in rounds/minutes and such don't matter so much and I can just handwave them away as mechanical game effects, it;s the mid-and long-term units which are the problem.)

I am trying to avoid arbitatily assigning a "day" period "eats?", at least not without considerable thought. It might be necessary in the end, but dang it if I'm not trying to make an effort to give it as much investigation as possible beforehand.




as for somebody whose job is to keep passge of time... it's not impossible, but my gut says they wouldn't even conceive passage of time as we do. they do not experience progress like we do. therefore, they wouldn't see time as a past and future. they'd see it as a static thing, where nothing ever changes really. there is the tribe, and before i was born there was the tribe, and after i'll die there will still be the tribe, and why should i care about the passage of time if nothing ever really changes

The campaign - if it ever comes to be - would predicated, ironically, on a major change. My intention was that they would be essentially a fishing village on the edge of a large inland lake/swamp bordered by mountains. (There is a gas giant in the system in resonance, which creates some volanicity, so everything isn't flat.) The lake was blocked off from the sea by a deterioriting land wall, and would be finally breakign down and flooding the region, forcing said tribe to embark on an oddsessy through the mountains and out.

However, to go a bit deeper, the world acually changes quite a lot, is just the changes tend to happen on the lifecycle of civilisations, not people.

To whit: in addition to the very slow creeping shift of the day/night lines, every so often (and a semi-random interval), the star dims. (The idea is based on RCB variable stars, which change in brightness - not much change in the IR specturm, mostly just visible - but turned up to 11). So you have a world where civilisations develop and sometimes get quite far, and then are plunged into a literal dark age when the sun dims, leading to extinctions... Until the next time. But the periods are long enough that the successive lot generally doesn't even know it happened, basically. (Funnily enough, when nothign changes for a very long time, every tends to get fracked up when it changes rapidly.)

(Meaning a campaign world full of Stuff To Explore...)

Some of the inspiration from this comes from an old Doctor Who episode (3rd or 4th Doctor, I think?) wherein the Doctor and co visit a planet appearing to be suffering from a Horrible Mutant Plague, but it turns out their planet has a stupid long eccentric orbit or something, and every so [however long], the climate changes and their biology adapts and they, like, change into crab people or something for the harsher "winter" conditions. I.e., the biology (and that of the planet) is geared up for the change, but the civilisation ISN'T, queue panic.



BUT. In this specific case, taking what you say into account, one might observe that it could be a thing for the PCs to have to DEVELOP a method for keeping time, as they now require it as they have had to leave stasis behind, which is not something I'd previously considered. (Still means I have to know what the resource usage time limit, is though.)

(They were already intended to be in a position where, nevermind a bag of holding, a BAG is valuable treasure...! Though it is surprising what technology they DID have in the approximate period on Earth.)




ok, i missed that part earlier. so they will have "weeks", after all. could be useful to measure time in the middle ranges, like "to reach the pastures to the east, we have to march for two weeks". but it wouldn't be a big part of people's life.

it can be hard, but you have to get out of modern scientific accurate mentality to understand neolithics tribes.
once an anthropologist visiting such tribes in the real world asked how far was the nearest village, he was told "two rice cookings". as in, start walking, and in twice the time it takes to cook rice, you'll be there. this is also something that they could do on your planet.
and it's a terrible measure for us; it depends on whether you like your rice hard or soft, how fast you walk... but it's good enough for a society that does not have to wake up at 7 am sharp to take the bus.


I am wondering now, with the suggestions, perhaps adulthood might be a measure of two factors; size and, as suggested, the onset of "puberty" (or whatever passes for it). The second would be the primary determining factor, but with the proviso that this is not generally assumed until a creature is of a specific size. (Assuming it does not have a very evident juvenile stage, like birds or something. I have not ruled it out; currently, the species in question is not even fully realised yet, all I have is the image that their lower half has a stance like a geranuk standing...)




Even if the planet is tide-locked, that only affects its own rotation; it continues orbiting around the star, and thus its view of more distant stars is constantly changing.

That will establish the planet’s year—but if that’s thousands of our years, then you’ll need another metric. If there are other planets in the system, their motions will help establishing a cycle.

Note also that a larger planet is likely to have a number of larger moons, and their motions would be complex but predictable, in the same way that we can measure the 4:2:1 resonance of orbital periods for the inner three Galilean satellites of Jupiter.

The planetary year is 1197.15 earth-years, for the record.

There are other planets - one of them being a gas gaint whose mass in resonance means that there is still some volcanitiy on the tidelocked planet.

But again, the problem is that most of the time, the sky is overcast with clouds (see below).




I’d be very interested in seeing more of this. My only sense of tidally locked planets is the born-of-a-red-dwarf variety, so I’m wondering how this is possible at +500 AU, or whatever distance you’re using.

Also, is there a real-world example you’re basing this on? And how is this planet warm enough to support vertebrate-analogue life?

Tide locking is, fundamentally, a function of angular momentum. Most tide-lcoked bodies are ones that are close to a larger bodt and are decelerated by the forces imparted by said body. But fi the body doesn't have much momentum itslef, it doesn't take as much to slow down. (And planets have different angular momentum, as day length is not actually related to orbit length, for example.) This particular world formed with a low angular momentum, and probabaly had that been lowered even more by an early stellar impact at exactly the right angle. Statistically *unlikely*, but no impossible.

The planet Andorliane, is sitauted 130AU out from (as mentioned above) plot-fied RCB variable star of 0.8sol mass and 96 sol in diameter. At that distance, taking into account the albedo effect of stabilising cloud feedback, the stellar flux is 2300W/m2 (Earth's is 1360W/m2, meanign a planet about an average of 3.9K warmer. (Though the temperature range will be different.)

As fot the climate, one particular paper I was pointed to suggested that clouds would stabilisie the temperture by increasing the albedo. Thus, you would have a permenant tropical storm on the substellar point (the closest to the sun), drawing in air at ground level towards it and then expelling cloulds in the upper atmosphere, where they would go over the rest of the planet and fall. There is a large (temperature stabilising) sea on the night side as well. So the climate would actually be very wet on the light side and progressively drier and darker as you moved towards the night side.

(And hense the cloud cover.)

Andorlaine is thus otherwise almost clone of Earth in other respects, because moving further outside that boundary would invalidate what I had to work with.




The more pressing questions are how to get the star to LAST stable long enough to have life forms, and with the specific star in question and the set-up, the answer was fundamentally "we-don't-know-ism..." The worst question came when, having done all the calcs, it came to "how does the stellar wind not blow the atmosphere off to which (not even being able to calculate stellar wind of anything, really having to shrug and go "it just doesn't, okay! There's like, magic particles or something!" I don't object to using that sort of explanation, but I prefer not to have to lean on it unless I absolutely have to and otherwise stick within the "plausible but unlikely" area if I can.)



Edit: TenLongFingers on the speculative evolution reddit suggested the genuious idea of using "babyfeedings" as the base unit of time, i.e. the approximate period between when the baby has to be fed (which is your "hour"). Combined with gestation time and weaning (which would be akin "year" or something), it strikes me as much better and elegant solid temporary basis to work from that, like crop growth times or "how long until the meat rots." It makes a great deal of sense, too, for a primitive society still largely in the hunter/gather stages to be focuessed on that, as well. It simply never occurred to me to use that as a metric, but if seems to fit the best of anything suggested so far!

[Sneak Dog]

It is not unlikely a tribe has a specific plant or mushroom it values, a multi-purpose one it relies on. So the growth cycle of such a thing would be a natural timekeeper, as they'd revolve their daily lives around them. Alternatively an animal. Perhaps a nomadic one, traveling to acquire all the necessary things they need for their complex metabolism. Specific minerals like salt, specific plants that create weird poisons these creatures need or whatnot.
(Cue confusion when meeting new people with a different way of life.)

[Palanan]

Originally Posted by Aotrs Commander
…but it turns out their planet has a stupid long eccentric orbit or something, and every so [however long], the climate changes and their biology adapts and they, like, change into crab people or something for the harsher "winter" conditions.

Have you read A Deepness in the Sky by Vernor Vinge? Fascinating look at a civilization that’s developed around a variable star that occasionally plunges the entire planet into an unlivable ice age. Apart from being a phoenomenal book, you might also get some ideas for your setting here.


Originally Posted by Aotrs Commander
As fot the climate, one particular paper I was pointed to suggested that clouds would stabilisie the temperture by increasing the albedo.

Not sure if I follow this part. Increasing albedo means increasing the proportion of energy reflected away, so less gets through to heat the planet. This is why glacial periods can lead to a positive feedback that ends in a Snowball Earth scenario.

Do you happen to have a citation for that paper, or a direct link?


Originally Posted by Aotrs Commander
There is a large (temperature stabilising) sea on the night side as well. So the climate would actually be very wet on the light side and progressively drier and darker as you moved towards the night side.

Depending on the extent and volume of that night-side sea, it might be a major factor in countering the drying trend. Here in the US we have what’s called lake-effect snow from our Great Lakes, and your night-side sea might end up doing something similar.


Originally Posted by Aotrs Commander
My intention was that they would be essentially a fishing village on the edge of a large inland lake/swamp bordered by mountains.

For timekeeping in this scenario, I think your best bet is to go with lunar tides. People living by the water’s edge are highly observant of and sensitive to any changes to the water’s edge, so even minimal tides would make for a noticeable cycle, especially if it’s the only constant cycle they have to work with. They would likely have different terms for high, low, and slack tides, and that would be the best external way of keeping track of time.

For longer periods, something like a “thousand-tide” could work as a measure roughly equivalent to a year (assuming for the moment they use base 10), with even longer periods reckoned in multiples of thousand-tides. Combining tides with measurements of the nearby gas giant and its moons, they might eventually develop something as complex and mathematically sophisticated as the Mayan long-count calendar.

Note also that our own moon raises six-inch tides in the continental crust, so if your Andorlaine sentients are especially sensitive to the earth beneath them, they might use similar land tides as an adjunct for water-tides.

[King of Nowhere]

This sounds highly suspect and likely apocryphal. Do you have a citation?

how the hell do you expect someone to remember the source of something like that? what are the chances that anyone could provide sources on such an internet debate?

But I do.
jared diamond, guns steel and germs.
i remember it because it's the only book on such a topic i ever read, and it was quite controversial in its thesis. i have no reason to doubt such an anecdote, though.
and frankly, what would be suspect about it? would you expect a tribe that never advanced past stone tools to use kilometers or something? even as late as the middle age people didn't care for precise time measurements. people set appointments at noon, or at dusk, and then somebody would arrive one hour before the others, or something (alessandro barbero, famous italian history communicator, of whom i listened to dozens of hours of conferences. don't ask me from which one comes this specific bit, though).




How do I track the usage and consumption of resources? As I said, it's fine to simply say "each tribesperson needs 1 food and 1 water per" but the problem now becomes how to determine what per what. Distance might be partly one answer, but then how do you measure it if they stop?

(Small stuff like durations of effects in rounds/minutes and such don't matter so much and I can just handwave them away as mechanical game effects, it;s the mid-and long-term units which are the problem.)

I am trying to avoid arbitatily assigning a "day" period "eats?", at least not without considerable thought. It might be necessary in the end, but dang it if I'm not trying to make an effort to give it as much investigation as possible beforehand.


it may be inevitable as an abstraction. still a realistic one; just because people eat when they are hungry and not when the sun sits high in the sky, it doesn't mean they'd eat a different amount of food overall.
oh, fun fact: the main reason to stockpile food and count it was to survive winter. in summer you get plenty of food, more than you can eat, but in winter there is less foood. so you have to stockpile food for the winter, and you have to invent math to judge if you can support your population.
but without winter, none of this applies. of course, you'll still want food stockpiles, but it's no longer critical for immediate survival.



(There is a gas giant in the system in resonance, which creates some volanicity, so everything isn't flat.)

ah, that's an astrophysics mistake, but one that can be easily fixed.
a gas giant would not cause gravitational heating unless it was really, really close to your planet. it would need for your planet to be orbiting the gas giant itself, and very close, for it to have a significant effect; jupiter has 0 effect on us, except when it intercepts asteroids. and in this case, your planet would not be tidally locked to the star. how could a moon of a planet always show the same face to the star?
however, there's no need for tidal heating to justify tectonic activity. you get that on any planet, until the nucleus cools down too much. you can keep tectonic activity without any interloping gas giant.



To whit: in addition to the very slow creeping shift of the day/night lines, every so often (and a semi-random interval), the star dims. (The idea is based on RCB variable stars, which change in brightness - not much change in the IR specturm, mostly just visible - but turned up to 11). So you have a world where civilisations develop and sometimes get quite far, and then are plunged into a literal dark age when the sun dims, leading to extinctions... Until the next time. But the periods are long enough that the successive lot generally doesn't even know it happened, basically. (Funnily enough, when nothign changes for a very long time, every tends to get fracked up when it changes rapidly.)

(Meaning a campaign world full of Stuff To Explore...)

nice idea, i like that



The more pressing questions are how to get the star to LAST stable long enough to have life forms,
that's my main issue. a star so big must be a blue supergiant, and those last only a few tens of millions of years. but this level of detail, i'm generally willing to handwave


and with the specific star in question and the set-up, the answer was fundamentally "we-don't-know-ism..." The worst question came when, having done all the calcs, it came to "how does the stellar wind not blow the atmosphere off
that's actually not the main problem. i'm not sure how strong the solar wind from such a star would be, but the planet is also extremely far from it. it's got to be a lot less strong by the time it reaches the planet. in fact, chances of habitability are better than around a red dwarf.

[Mastikator]

Anyone on the twilight region of a tidally locked planet will notice the stars rotating in the sky as the year goes on. People on earth noticed how the stars moved throughout the year and that was with a day/night cycle interfering, they did this thousands of years ago, many cultures did it independently.

So a rotation is still a year.

[Aotrs Commander]

I have had an unpresedented amount of people replying to the places I posted this up, which is quite shocking (normally in the past, I tend to find I get one or two, but today I can barely keep up, so forgive me if I don't respond to everyone and everything as exhaustively as I normally do. Like, I went out for an hour or an came back and I've been typing up stuff for the past nearly hour, hour-and-a-half! Frack, I wish the lore guff I put out for the main stuff I do got this kind of interest...! Or, like, ANY interest...)



Have you read A Deepness in the Sky by Vernor Vinge? Fascinating look at a civilization that’s developed around a variable star that occasionally plunges the entire planet into an unlivable ice age. Apart from being a phoenomenal book, you might also get some ideas for your setting here.

Yes, actually, and I'm pretty sure it (and the other one in Zones of Thought) were suggested in previous dips into this topic.



Not sure if I follow this part. Increasing albedo means increasing the proportion of energy reflected away, so less gets through to heat the planet. This is why glacial periods can lead to a positive feedback that ends in a Snowball Earth scenario.

Do you happen to have a citation for that paper, or a direct link?


how the hell do you expect someone to remember the source of something like that? what are the chances that anyone could provide sources on such an internet debate?

Acually...!

I do, because I can find the thread where it was suggested to me!

Link (https://arxiv.org/abs/1307.0515)

Here is the thread (https://www.physicsforums.com/threads/help-with-orbital-mechanics-for-an-unusual-alien-planet.751598/) (from 2014) which got the ball rolling, if you're interested.

It's stabilisation; the star throws out a frasck-ton of stellar flux (because is has a luminoisity of 18818.09909), so the high albedo is needed to keep the planet from entirely boiling off as much as freezing.



I am definitely thinking that the suggestion of using the tribe's own procrastion/maturity duration is the best first yardstick to use (especially since i can ball-park it from similar-sized creatures from Earth).

It has been observed that, for the most part, it's likely that there would be defined no cycles for life as such. However, that said, intelligent creatures might well still need a period of "sleep" or equivalent to get rid of the neurochemical build-up in the brain; so I'm leaning towards the intelligent life (or at least some of it) requiring some form of rest perdioically.



that's actually not the main problem. i'm not sure how strong the solar wind from such a star would be, but the planet is also extremely far from it. it's got to be a lot less strong by the time it reaches the planet. in fact, chances of habitability are better than around a red dwarf.

At the time, I could find no information of stellar wind strength to be able to make any kind of calculations to make an attempt, so I had no basis to even get that sort of information you've just given me.

[King of Nowhere]

At the time, I could find no information of stellar wind strength to be able to make any kind of calculations to make an attempt, so I had no basis to even get that sort of information you've just given me.
I don't know if we even know how strong is the solar wind around other stars. I mean, we certainly have experimental data only for our own. I'm sure we have mathematical models, but good luck knowing them unless one works in the field.
that star is a lot hotter and brighter than the sun. it's got to also have a much stronger solar wind. however, its planet is also a lot farther away, so that in the end it gets roughly the same light as our own. from a layman perspective, assuming that at that distance you also get a similar amount of solar wind makes sense.
plus, solar wind takes billions of years to strip away an atmosphere. well, no, ok, it depends on the planet, its magnetic field, and the strenght of the solar wind. anyway, the only major problem - one requiring handwaving - is that a star such as you describe would only burn for a few tens of millions of years, not enough time to get life - not enough time even to make a stable planetary system.

[Mechalich]

one requiring handwaving - is that a star such as you describe would only burn for a few tens of millions of years, not enough time to get life - not enough time even to make a stable planetary system.

I think a captured rogue planet would work. A supergiant is certainly capable of that feat, and it might even explain the weird scenario of such a distant planet in a tidally locked state. Such a planet could have life sustained in areas heated by radioactive decay and/or volcanic processes that massively expanded and got bigger quickly in response to a dramatic increase in temperature. Size is a fairly plastic trait in evolution, so assuming relevant precursors existed things can get big fast.


Regarding the time issue note that life on Earth does just fine in environments with constant conditions and no visible cycles, notably the abyssal zones of the oceans. Ecosystems can handle this scenario just fine. Sapient beings might struggle a bit more, but, of course, if environmental conditions are more or less constant there is far less urgency to everything, because events are either continuous (ex. marine snow rates) or random (ex. whalefalls), not cyclical, and therefore matching timing to exploit cyclical resources is unnecessary.

[Mutazoia]

https://www.youtube.com/watch?v=EuBy3_kNJQk

[Duff]

Animals (including people) on this world are unlikely to have a sleep cycle, given sleep seems to have evolved mainly as a way to keep animals out of trouble when the light/temperature conditions are wrong for them (according to a New Scientist article I read years ago.
It has since been put to other uses such as assimilating memories etc and we need it now. But if there's no reason to develop a "shut down mode" then there's no reason to find a use for it.

And if there is no predictable seasons, as noted, there is no time for seasonal things to happen. That probably means plants that want to cross pollinate will always have some flowers and some fruit.
Animals will also not have a breeding season.
Though there is likely to be a level of "After it rains" or "when it's hot"

But maybe some strange animal develops a mysterious way to synchronise their cycle; such as detecting a galactic magnetic field.
This would be very strange. In a world where every day is very similar, for some reason suddenly all the turtleducks everywhere have babies.

So how do you measure time for rations?
I'd go the lunar week. I think the only other common time would be breaths. "I'm going to hide behind that tree. Count a hundred breaths, then chase the deer toward me"
Others might be used, but I think they'd be rare because it seems likely, as others have said, that the whole concept of time would be too abstract. But some that could be used are:
The length of time a single flower/fruit/leaf lasts. "When that individual fruit is ripe". "When a Flower that has opened today falls" The terms used would be based on the plants in the area.
There might be phenomena in specific places that also give a measure of time like "Old Faithful" the geyser in some places.

Maybe there's an island where there's a plant that flowers in the full moon and people there have "days" of the week. Bud day, Flower day, drop day (for when the flowers drop), swelling day, green day and ripe day. Maybe lots of plants do this. It wouldn't have to be the same flower doing everything in the 6 days. "Swell day" might simply be when the newest fruit start growing. But they might take a week or 5 to actually be the almost ripe ones on Green day. Or maybe they are small berries that really do cycle through that fast. These people who have a concept of time are considered weird by others

Tribes may migrate to avoid hunting/harvesting out an area, but the time to move on is "When the food runs low" rather than any specific time of year. Two neighboring groups that get along well might travel along the area where their territories border* in opposite directions to maximise the chance of meeting up. Maybe these meetings become the festivals, but they may never come up with the idea of trying to "synch up" because it's impossible. The whole concept isn't there.
Though, for example, a volcano that erupts reasonably often might be an event marker. "When The Mountain starts to smoke we gather in the far valley for a festival" might work. This could be variable. The bigger the smoke, the more tribes come

Geography wouldn't have the north south divide. The primary directions are "Sunward" and "Darkward". Then secondary directions might be "Left" and "Right" when you face the sun. Or Moonward and "Antimoonward".
Depending on whether the moon is orbiting in the same plane as the planet or at an angle, it will either define where the equator is or define a direction relative to the twilight ring. You walk with the moon or you walk opposite to it.

* Exact borders are a relatively new idea on earth. I don't see why this would be different

[VonKaiserstein]

Even in the absence of a light cycle, natural rhythms would evolve, though they may be driven by stimuli we don't understand. Look at your real world equivalents. Cave dwelling creatures develop activity/rest cycles, even if their eyes have become vestigial. These cave fish keep a 47 hour day. https://www.livescience.com/15923-blind-cave-fish-circadian-rhythms.html . Though much harder to study, I'd look at really deep sea creatures as well. Below a certain depth, conditions are relatively uniform at all times. There are others that have broken free of all of our terrestrial timekeeping- cicadas, and their emergence every 13 or 17 years. What stimuli caused that evolution?

For all of that- our own full night's sleep isn't really biologically motivated. In the absence of a clock, most humans will trend toward biphasic sleep- https://www.bbc.com/future/article/20220107-the-lost-medieval-habit-of-biphasic-sleep .

With neolithic hunter gatherers, I suspect you'll have a leader setting the pace for the tribe. Likely a horn or drum to awaken everyone and get them going. Other than cooperative tasks, there isn't nearly as much need in that sort of society to be 'on time' in the way we think of it. It's not like tribesmen are coming back to the village for lunch, or you can't just wake Joe up if you need to barter with him urgently for some reason. What would be the need for time in a neolithic culture? You have to eat, you have to find shelter, you have to do all the survival tasks, but does it matter if you do them in 5 days, or 7 days? There's a definite, and often fatal window of going too slowly about your tasks... but otherwise, you're just a hard worker who can have the chance to catch some more fish, or plant another row of crops, as opposed to your next hut neighbor who's just getting by and sleeps more.

[Palanan]

Originally Posted by Mechalich
Regarding the time issue note that life on Earth does just fine in environments with constant conditions and no visible cycles, notably the abyssal zones of the oceans.

We know so little about the deep pelagic regions that it’s unwise to make any sweeping claims about what might or might not be going on. As noted with the cave fish, organisms often have complex and unexpected cycles, and the deep pelagic regions are simply too poorly explored to say they don't have something similar. They may be uniformly dark with regards to sunlight, but they're not isolated and they're definitely not unchanging.


Originally Posted by VonKaiserstein
There are others that have broken free of all of our terrestrial timekeeping- cicadas, and their emergence every 13 or 17 years. What stimuli caused that evolution?

Periodical cicadas have not “broken free” of the annual cycle—in fact it’s the opposite, as their name itself will tell you. Their survival is dependent on their being precisely attuned to the passage of years.

It’s no accident that 13 and 17 are prime numbers, and the broods emerge on that schedule en masse to overwhelm their predators. Their emergences are staggered throughout their range, and the prime-number timing helps to prevent predators from evolving a similar pattern.

Most cicadas are not periodical, but they’re still closely tied to the seasons, and the species in a given area will have a reliable sequence of emergence, from late spring through late summer. This is most likely a form of niche partitioning. Whether annual or periodical, cicadas are an excellent example of a species group finely calibrated to the solar year.


Originally Posted by VonKaisterstein
With neolithic hunter gatherers, I suspect you'll have a leader setting the pace for the tribe. Likely a horn or drum to awaken everyone and get them going.

Any “leader” who tried that wouldn’t stay leader for long. People living close to the earth usually wake with the sun without much need for outside help. To say nothing of help from the rest of their environment when dawn arrives, from domesticated roosters to the entire dawn chorus of birds.

[Pauly]

This sounds highly suspect and likely apocryphal. Do you have a citation?

As a young pup growing up in the outback of Oz, we measured the distance between towns in “beers”. If a town was 6 beers away you could drink 6 beers on your way to it.

Citation: me

[Pauly]

A couple of people have mentioned sleep. Life on Earth has evolved to sleep, and sleep is an essential brain function, but it shouldn't be confused with rest, which is physical recuperation.
Organisms on Earth have evolved to sleep primarily at night or in the day depending on when it is safest for them to sleep.

In a tide locked situation there is no ‘safe’ time to sleep, so it is highly likely that organisms there don’t sleep as we do on Earth. Maybe they just don’t sleep at all, only rest when they’re tired. Maybe they sleep like dolphins, half a brain at a time, during which time they’re semi-dormant but capable of going fully active in an instant.

The basic timekeeping units in human history are days based on the Earth’s rotation, month based on the moon’s orbit and years based on the earth’s orbit around the sun. Seasons are not standardly measured across cultures/locations, but act as a subdivision of years, weeks are a subdivision of months and morning/midday/afternoon a subdivision of days.

There is a moon in the OP, but one that is not easily or reliably observable to the populace. In the absence of an easily observable effect it makes it difficult to see it becoming a basic time keeping unit.

For something ti become a basic time keeping unit it has to be reliably observable, constant, and widespread.
Some suggestions.
1) time it takes for a seed to sprout.
2) the time it takes to travel a standard distance, although that would start as a local measure of time which would then be standardized later by a civilization.
3) the time it takes to cook a basic food type. I’m thinking specifically of boiled rice which is cooked at a constant temperature.

[gbaji]

Not sure if others have commented fully on this (saw a couple points, but seemed to be going in a different direction. But I do have some questions about these bits:


So. Because the world is tide-locked, there is no day/night cycle and there are no seasons (the orbit cannot be erratic). So you can't measure time by the sun or the stars. In any case, as the plant remains largely habitable by the stabilising feedback of clould cover, the sky isn't always readily visible (and it's often raining). At ground level, there is a continuous stiff breeze coming from the dark side to the light side (again, part of the researched climatic conditons).

...

2Strictly speaking, it's ins't 100%, but the day length is also in thousands of Earth-years at a minimum.



To whit: in addition to the very slow creeping shift of the day/night lines, every so often (and a semi-random interval), the star dims. (The idea is based on RCB variable stars, which change in brightness - not much change in the IR specturm, mostly just visible - but turned up to 11). So you have a world where civilisations develop and sometimes get quite far, and then are plunged into a literal dark age when the sun dims, leading to extinctions... Until the next time. But the periods are long enough that the successive lot generally doesn't even know it happened, basically. (Funnily enough, when nothign changes for a very long time, every tends to get fracked up when it changes rapidly.)

You declared this to be "tidally locked", but it doesn't look like you are describing that. A tidally locked planet is "locked" with the exact same point on the planet pointing directly at whatever it is orbiting around (the star in this case). It has no day or night at all, with one side always facing the star, and the other side always facing away. In this situation, there is no movement of a day/night line at all (not even super slow), and no "constant wind" (because how does the air get back to the other side?).

What you seem to be descrbing is not that. You mention a "day" being thousands of years, and the "slow creeping shift of the day/night lines". This suggests that the planet is not actually tidally locked, but doesn't rotate at all. It's always oriented the same way relative to the stars outside the system, and therefore actually has a "day" that is the same period as an orbit around its star. So the inhabitants wouuld not see the stars change at all (always facing the same direction), but over time, the star would shift (but very slowly). I mean, you can refer to that as one rotation of the planet (from a stellar point of view), but it would not be seen as a "day" from the point of view of people living on it.

I'm not sure it's actually physically possible for a planet to maintain that sort of alignment (would assume it would either spin on its own, or gradually become locked, not just stay facing one direction like that). Planets form by spinning collections of stellar "bits", that due to gravity gradually must form and spin wherever there's an imbalance in matter distribution (do some research on formation of objects in an "almost perfectly evenly distributed mass cloud", and this is what has to happen). They will always have their own spin (and there's actually some formulas for determining what that spin would have to be based on the makeup of materials in the body itself). The spin will only ever stop if there's something else pulling it in a given direction. So a spinning top stops always leaning "down" towards the surface due to gravity. Same deal with planets/moons (any orbiting body). They should only ever "stop spinning" because of an imbalance in mass density on the planet itself which "stops" facing the body it's orbiting.

It should either spin much faster than that *or* always face the same side to the star. At least that's my understanding of the physics involved. The only thing that I can think of that would cause it to behave the way you are descrbing is some sort of gyroscopic effect, which I'm also scratching my head over because that requires spin too (and is what actually causes spining planets to maintain their axial angles).

[Lord Torath]

Further on that, the recently-captured moon will drag on the planet, causing it to spin. Don't suppose you've got What If by Randall Munroe? One of the questions is about what would happen if the Earth suddenly stopping rotating (day = year). The moon would slowly kick it back into gear. But we can pretend that it wouldn't since that's the set-up you want.


Anyone on the twilight region of a tidally locked planet will notice the stars rotating in the sky as the year goes on. People on earth noticed how the stars moved throughout the year and that was with a day/night cycle interfering, they did this thousands of years ago, many cultures did it independently.

So a rotation is still a year.Well, keep in mind that a year is 1150-ish Earth Years, so roughly 23 paleolithic lifetimes (assuming a 50-year stone-age lifespan, which may or may not be accurate).


So first, we need clarification on whether the planet is tidally-locked to its star (regardless of the fact that it's too far away to be affected that way - tidal forces fall off at the rate of one over the distance cubed, so Earth feels 2.2 million times stronger tidal force from the sun than this planet would clear out at 130 AU), or whether it is... let's call it gyroscopically locked... with respect to the rest of the universe (it's probably not spinning nearly quickly enough to be a gyroscope, but I'm proceeding on the basis that your set up works for whatever reason). In either case, the stars/terminator would move much too slowly to be noticed in one person's lifetime.

I would expect most plants would be dependent on animals to spread their seeds. You might run into the situation in KungFu Panda, though, where the peach tree has both fruit and flowers on it at the same time.

Daily time/distances could be measured in "rests", since, as was mentioned above, people still need breaks from physical activity, even if they never actually sleep. As others have mentioned, shorter times might be measured by the life of quick-blooming flowers, or how long a decent-sized branch needs to burn down. I like the "breaths" as a unit of time as well.

If the moon is visible (and I'm not certain why it wouldn't be visible, if it's still 1/2 a degree across as viewed from the surface of the planet), then 6-earth-day Months would almost certainly be a thing. So distances could also be measured in months of travel.

People would probably measure their age in... Ages. The first Age might be when they're around 5-6 in Earth years, and are old enough to have made it through the various child-hood diseases/predators that might regularly claim the young. Second Age might be puberty. Third Age when they've hit full growth. Fourth Age when they're no longer fertile and/or vision starts going. Fifth Age when their teeth are worn down.
There might be earlier ages based on walking/weaning, I don't know.

Regarding the solar wind, it'll be about 16,900 times weaker than it would be at 1 AU, since it drops off by one over the distance squared.

Radioactive elements in the crust, mantel and core will keep plate tectonics going, as well as providing a magnetic field to protect against solar wind/cosmic rays. Of course, if the core is rotating, that would tend to impart a rotation to the rest of the planet, which could conceivably be balanced by the moon if the moon is rotating in the opposite direction.

[gbaji]

I suppose we could speculate that this is a universe not bound by Newtonian physics, but actually has some sort of "clockwork heavens" system in place. The planet is actually stuck in a band of "ether", and is held in place, moving along its path, but always facing the same direction (relative to an external POV). All other objects are as well.

You could make it work, of course, but it would not follow the rules of orbital bodies. Doesn't need to though!

[Palanan]

Originally Posted by Aotrs Commander
There are other planets - one of them being a gas gaint whose mass in resonance means that there is still some [volcanism] on the tidelocked planet.

Not sure if this will be feasible. In order for the gas giant to have enough of an effect to contribute to heating, it’ll need to be close—close enough that it will likely perturb Andorlaine’s orbit. But if Andorlaine has a thousand-year orbit, then the gas giant will only swing by on roughly the same timeframe. (If it orbits faster, then it’ll be closer to the star and won’t have any appreciable effect.)

In our system, Io is so volcanic because it’s being constantly pulled and counterpulled. But if Andorlaine’s jovian neighbor only comes by roughly once a thousand years, that’s nearly a thousand years for the crust to cool off between visits. I can’t see that having any significant heating effect.


Originally Posted by Duff
…I think the only other common time would be breaths. "I'm going to hide behind that tree. Count a hundred breaths, then chase the deer toward me"

If Aotrs doesn’t want to work with tides, then this is probably the easiest and most natural way to go for the building blocks of time measurement.

—Assuming that these sapients breathe the way we do, and don’t use qorii-tendrils to pull oxygen from their llyrx-pouches.


Originally Posted by gbaji
I mean, you can refer to that as one rotation of the planet (from a stellar point of view), but it would not be seen as a "day" from the point of view of people living on it.

This is something like the situation on Mercury, where the “day” is longer than the orbital period. On Mercury this causes some rather unusual sunrises and sunsets, with the sun pausing and reversing before reversing itself again.

What this seems to mean for Andorlaine is that over centuries or millennia, the former dayside will eventually become the nightside, and slowly back again. That right there could give you a slow rise and fall of civilizations, since cultures that develop around specific resources or geophysical features would eventually need to migrate when those resources and features went through the twilight band into the opposite side.

I could see the evolution of two sharply different realms of flora and fauna, each adapted for either dayside or nightside conditions. As the planet slowly turns, biomes adapted for the dayside would need to find some way of ensuring that their propagules could survive a long passage through the nightside—while at the same time, long-dormant seeds and eggs of nightside biota would be reawakening after thousands of years of quiescence during dayside conditions.


Originally Posted by Lord Torath
…as well as providing a magnetic field to protect against solar wind/cosmic rays. Of course, if the core is rotating, that would tend to impart a rotation to the rest of the planet….

This is a real kicker. You need a spinning molten core to generate the magnetic field, which prevents your atmo from sputtering away and thus prevents your oceans from evaporating off. But the spinning core will have an effect on your planet’s overall spin, and I’m not sure if the moon can counteract that.


Originally Posted by Aotrs Commander
There is a planet. It orbits around a large star whose goldilocks zone is significantly far from the star that the orbit is measured in thousands of Earth-years1. The planet is tide-locked2.

…Because the world is tide-locked, there is no day/night cycle and there are no seasons (the orbit cannot be erratic).

Given the issues with the not-quite-tidal-lock, the long-duration “day” and the complex impacts on biota and cultures, plus many of the other things mentioned here, what about your underlying concept is most important to you?

A world with a thousand-year orbital period is a great concept; a tidally locked world is another one. But combining the two is proving to be a real bear, and I have to wonder if it’s this combination which is central to your concept, or if there’s some other way to approach what you’re interested in.

[Mechalich]

A world with a thousand-year orbital period is a great concept; a tidally locked world is another one. But combining the two is proving to be a real bear, and I have to wonder if it’s this combination which is central to your concept, or if there’s some other way to approach what you’re interested in.

A better combination is probably a planet like Uranus. It has a long orbital period and because of its extreme axial tilt, the poles face either toward or away from the sun and experience half the orbital period as continual light and half as continual darkness. Assuming a 1000 year orbital period, that would be 500 years, which is probably long enough.

This would also eliminate the timekeeping issue, because the planet is still rotating in reasonably rapid fashion that could be measured against the starfield or any moons, it simply wouldn't influence the day/night cycle.

[Duff]

I'm not sure it's actually physically possible for a planet to maintain that sort of alignment
It could be in the late stages of becoming tidally locked.

Or, I think it would be possible for the newly arrived moon to have just slightly "unlocked" it

And a suggestion for keeping tabs on rations.
For game purposes, have a standard food bag.
A bag of food is both an amount of food, and the time it takes to consume it. You could call them days if you want.

You have 6 bags of food in the warehouse. You harvest 5 bags from the potato field in the time it takes for 1 person to eat a bag of food. It takes 5 people to run the potato field.
The potato field just breaks even on food
If it takes 7 footbags of time to improve the potato field, the community is going to need to build better reserves

[GuzWaatensen]

Hi that’s quite an interesting discussion and I just want to throw a couple of points into the arena for your consideration.

1. As others have pointed out an aeon-orbit tidal locked planet doesn’t make a lot of sense based on our current (admittedly limited) understanding of exoplanets. As the tidal lock itself already removes the day night cycle I don’t know why the long orbital period is necessary to your setup. A tidally locked planet much closer to the sun could be just as interesting. You‘ll always have to explain why there‘s an atmosphere either way, if you want to not just hand wave it of course.

2. How life would measure time is an interesting conundrum. I disagree with some of the statements that this might be irrelevant, there’s likely always a need to coordinate cycles between different plant and animal life. This could of course be done through other means than celestial time givers. One interesting proposal could be a large macroorganism spanning almost the entire habitable side beneath the surface. It’s bodily functions could cause periodic tremors, eruptions or other phenomena that act as time giver for other lifeforms to base their cycles on.
And such an organism would add a third interesting trope into your fantasy world…

[Palanan]

Originally Posted by Mechalich
A better combination is probably a planet like Uranus. It has a long orbital period and because of its extreme axial tilt, the poles face either toward or away from the sun and experience half the orbital period as continual light and half as continual darkness. Assuming a 1000 year orbital period, that would be 500 years, which is probably long enough.

This would also eliminate the timekeeping issue, because the planet is still rotating in reasonably rapid fashion that could be measured against the starfield or any moons, it simply wouldn't influence the day/night cycle.

This is a good fix and could make for a really interesting setting, if applied to a terran or superterran world. Between the rotation and the potential for moons the timekeeping issue would be taken care of, and there’s plenty else to work with in the dynamics.

There’s still the issue of the inverse-square reduction in stellar output over distance, which makes it trickier to justify the extreme orbital period, but there are plenty of ways to approach that, including simply using a brighter star.


Originally Posted by GuzWaatensen
I disagree with some of the statements that this might be irrelevant, there’s likely always a need to coordinate cycles between different plant and animal life.

Very much agreed, I’d been meaning to comment on this point earlier.

Even in a setting without obvious natural cycles, species wouldn’t be likely to exist in some sort of unhurried stasis or otherwise be able to ignore time, because predation pressure will be a constant and that will drive the evolution of form and behavior. Reproducing at a constant low rate will only spoon-feed the predators unless there’s some other set of defenses involved. As with the periodical cicadas, some species might evolve mass reproduction to overwhelm predators and ensure that at least some progeny will survive.

And of course, the more complex the ecosystems the more complex the interactions and their timing. Note also that seeds have predators as surely as anything else, even if we tend to gloss over the distinction with general terms like “herbivores.” This means that seed predators will be exerting strong selective effects on the species they’re targeting.


Originally Posted by GuzWaatensen
One interesting proposal could be a large macroorganism spanning almost the entire habitable side beneath the surface.

This reminds me of the Amoebic Sea from Wayne Barlowe’s original Expedition. But whether surface or subsurface, the metabolism of a planetary organism could contribute significantly to local temperatures, which might help offset some of the issues from a wide orbit.

[Chronos]

I think you're going about it backwards. It's not "how many units of food do you eat in a day"; rather, they'd take some standard unit of food, and measure day-ish timespans by how many of those standard units you eat. Age wouldn't be measured in years, but in milestones. Even today, in some parts of the world where record-keeping isn't so great, people measure when a child is old enough to start school by the relative sizes of their arms and head: When you can reach over the top of your head to touch the ear on the opposite side, you're old enough. You wouldn't say "I'll be gone on this journey for over a decade"; you'd say "By the time I return, this newborn will have grown enough to have gone on his first hunt".

[gbaji]

A better combination is probably a planet like Uranus. It has a long orbital period and because of its extreme axial tilt, the poles face either toward or away from the sun and experience half the orbital period as continual light and half as continual darkness. Assuming a 1000 year orbital period, that would be 500 years, which is probably long enough.

I really like this idea. Allows for a more "normal" rotating planet (which eliminates some of the issues with air/wind), while retaining the "very very long day" concept. Unless, of course, the entire point is to have a planet with no (or very little) motions which would cause normal cycles to occur.



It could be in the late stages of becoming tidally locked.

Or, I think it would be possible for the newly arrived moon to have just slightly "unlocked" it

Yeah. Either could work. Another thing to remember is that orbital objects that have any influence on eachother gravitationally cannot have a stable orbital rate that is an exact multiple or factor of any other orbital object (the regular cycle will push/pull one or both slightly out of sync over time, or result in massive shifts throwing one of them off in a different direction). May not be relevant at all to people living on the planet and the presumed scale of any game setting you may choose to deposit there in a relevant time frame though (actually probably not).

The "recently arrived moon" concept is interesting, since we could assume a world that was much less vibrant/active (life form wise anyway) prior to its arrival (and "recent" in astrophysics terms can be 10s of millions of years or longer). Said moon could have actually kickstarted growth of more advanced life forms just as a result of "shaking things up". Could create some interesting cosmology angles there, depending on what kind of setting you are going for.



2. How life would measure time is an interesting conundrum. I disagree with some of the statements that this might be irrelevant, there’s likely always a need to coordinate cycles between different plant and animal life. This could of course be done through other means than celestial time givers. One interesting proposal could be a large macroorganism spanning almost the entire habitable side beneath the surface. It’s bodily functions could cause periodic tremors, eruptions or other phenomena that act as time giver for other lifeforms to base their cycles on.
And such an organism would add a third interesting trope into your fantasy world…

And also this. If you want to go all the way with "there's no planetary/tidal/seasonal time" bits, creating some sort of life that makes it own time in some way seems like a great idea as well. Some large macroorganism that manages this, perhaps on a planetary basis, and thus provides life cycling to all other creatures can also create a great backdrop depending on what setting is chosen (and frankly can support any number of them). Think like Pandora if you want, or something like that, but perhaps without the unobtainium (or maybe with it?). Could create a lot of interesting concepts.


if you do go with "extremely long day", one thing to consider is the concept that everything just moves along with the terminator. If we're talking around 1000 years for a single cycle, this is quite manageable, and could represent the concept that this one area would always be where life could survive easiest/best. People could form into nomadic tribes, who have travelled various routes (always going "east" or whatever), picking up every year or so and moving to the next valley. It could also provide an interesting game setting, since, assuming humans (or whatever) have been around for quite some time, there's the potential for building structures over time as well, and then settling and resettling into the same structures over and over as they move. And the potential for discovery. So maybe our humans are traveling along, as they always have through their history and come across something "different". Maybe a thousand years ago, their great ancestors developed more technology/magic/whatever, and now they're rediscovering that as they come across the long abandoned ruins of the last time they were there. Maybe some people tried to stay through the long night. What happened to them? Maybe other "things" are left from that age as well, which maybe ought not to re-awaken...

[Aotrs Commander]

You declared this to be "tidally locked", but it doesn't look like you are describing that. A tidally locked planet is "locked" with the exact same point on the planet pointing directly at whatever it is orbiting around (the star in this case). It has no day or night at all, with one side always facing the star, and the other side always facing away. In this situation, there is no movement of a day/night line at all (not even super slow), and no "constant wind" (because how does the air get back to the other side?).

According to the research, the substellar point forms a permanent storm, which heats the air and blows it out in the upper atmosphere (creating the semi-permenant cloud-cover), while drawing in the colder air at ground level (from the night side), in a giant atmosphere cell.


What you seem to be descrbing is not that. You mention a "day" being thousands of years, and the "slow creeping shift of the day/night lines". This suggests that the planet is not actually tidally locked, but doesn't rotate at all. It's always oriented the same way relative to the stars outside the system, and therefore actually has a "day" that is the same period as an orbit around its star. So the inhabitants wouuld not see the stars change at all (always facing the same direction), but over time, the star would shift (but very slowly). I mean, you can refer to that as one rotation of the planet (from a stellar point of view), but it would not be seen as a "day" from the point of view of people living on it.

The difference between 100% tide-locked and "maybe moves a fraction of a millimetre every few centuries" is largely academic, I feel.

Given even the (relatively limited) force the moon exerts, it would be logically impossible for Andorlaine to be 100% tide-locked... But the acceleration is so tiny as to be laregly unnoticable. Andorlaine is tidelocked bar the shouting.

For reference, my orignal look at it. (https://www.physicsforums.com/threads/help-with-orbital-mechanics-for-an-unusual-alien-planet.751598/#post-4769342/)

In short, the day length increase from acceleration from the moon is likely to be on the order on about 1 millisecond every century, assuming tidal forces equal to Luna on Earth. To get up from stationary to a sidereal day of 24 hours from a completely tide-locked planet would take three trillion years - well past the point the recent-capture moon either crashed into the planet or sods off into the void in mere few million years. (It is wasn't the moon would have been discarded.)

So, as a ball park figure, speed of earth's surafce at the equator over 24 hours is 460m/s. Proportionally, after a century of acceleration from an assumed complete stop, that gives us a speed of an approximate speed that would be 1/(24 x 60 x 60 x 1000)th of that, or 0.000005324m/s (i.e. 0.005mm/s). So the rotational speed will be increasing by an estimated 1mm every 20000 years. On a geological and civilisation scale, I think that's small enough to effectively not be a major concern, considering actual plate tectonics will be faster.


I'm not sure it's actually physically possible for a planet to maintain that sort of alignment (would assume it would either spin on its own, or gradually become locked, not just stay facing one direction like that). Planets form by spinning collections of stellar "bits", that due to gravity gradually must form and spin wherever there's an imbalance in matter distribution (do some research on formation of objects in an "almost perfectly evenly distributed mass cloud", and this is what has to happen). They will always have their own spin (and there's actually some formulas for determining what that spin would have to be based on the makeup of materials in the body itself). The spin will only ever stop if there's something else pulling it in a given direction. So a spinning top stops always leaning "down" towards the surface due to gravity. Same deal with planets/moons (any orbiting body). They should only ever "stop spinning" because of an imbalance in mass density on the planet itself which "stops" facing the body it's orbiting.

It should either spin much faster than that *or* always face the same side to the star. At least that's my understanding of the physics involved. The only thing that I can think of that would cause it to behave the way you are descrbing is some sort of gyroscopic effect, which I'm also scratching my head over because that requires spin too (and is what actually causes spining planets to maintain their axial angles).

Again, from the gentleman of the physics forum thread:


The thing is, the amount of angular momentum a planetary body ends up with after most of the protoplanetary debris had been cleared during the formation of the system can be almost anything, especially for smaller bodies(i.e., not gas giants). So you could conceivably have a planet that never really had much of angular momentum to shed, so it eventually did get tidally locked to the distant star, especially if given a lot of time.

I am not an astrophysicist myself, so I can only go with what people who actually know what the maths are tell me.

So, low natural angular momentum, followed by an early collision that hit exactly right to slow the rotation further is the assumed reason.

(It's actually 105 AU, not 130, that was me mis-remembering, not that it significantly makes a difference.)




Not sure if this will be feasible. In order for the gas giant to have enough of an effect to contribute to heating, it’ll need to be close—close enough that it will likely perturb Andorlaine’s orbit. But if Andorlaine has a thousand-year orbit, then the gas giant will only swing by on roughly the same timeframe. (If it orbits faster, then it’ll be closer to the star and won’t have any appreciable effect.)

In our system, Io is so volcanic because it’s being constantly pulled and counterpulled. But if Andorlaine’s jovian neighbor only comes by roughly once a thousand years, that’s nearly a thousand years for the crust to cool off between visits. I can’t see that having any significant heating effect.

On the one hand, going with what I was told and the gentleman was clearly thinking of Io's tidal heating.

On the other hand, a quick google search of the topic indicated that actually, Earth's volancity is powered primarily by isotope decay, residual formation heat and frictinal heating, so, actually, there's nothing stopping Andorliane having an active mantle at all (it is not significantly older than Earth), though it's fair to say the effect might be less that Earth's; but ti would still have plate tectonics.



This is a real kicker. You need a spinning molten core to generate the magnetic field, which prevents your atmo from sputtering away and thus prevents your oceans from evaporating off. But the spinning core will have an effect on your planet’s overall spin, and I’m not sure if the moon can counteract that.

I did look at that, and decided it was simply unworkable. Without being able to even ballpark the stellar wind (which as noted we don't even understand), I did resort of hand-wavium at that point. (As with "how has the star that should only last a few million years doing what it does lasted a few billion plus?")

(Still, whatever else, you cannot say I did not give this whole an absurd amount of consideration, compared to what most sane people would do.)


Given the issues with the not-quite-tidal-lock, the long-duration “day” and the complex impacts on biota and cultures, plus many of the other things mentioned here, what about your underlying concept is most important to you?

A world with a thousand-year orbital period is a great concept; a tidally locked world is another one. But combining the two is proving to be a real bear, and I have to wonder if it’s this combination which is central to your concept, or if there’s some other way to approach what you’re interested in.

It is, yes, in combination with the whole "the sun goes dim" thing. The changes happen, but belong the lifetime of civilisations.



(It's also worth noting that this is within the same universe which was retrocasually probability engineered to the point of duplicate planets appearing, so extremely implausible but statistically possible events1 (like the low momentum of Andorlaine) are by comparison, potential run-off.)



1By comparison, in Rolemaster a hobbit with a bent knife could theorhetically beat Morgoth in single combat, the but the probability makes it impossible on a practical level.

[Lord Torath]

How about a large cloud of dust that is at, say, 85-ish AU in a resonant orbit, and it blocks out the sun every couple-thousand years? Maybe a planet that was recently (a few million years ago) pulverized by a rogue planet from outside the system? I'm just spitballing here, so I don't know how much mass the cloud would need to block out the sun from 20 AU away, nor how long it would take to coalesce back into something that would no longer block the sun. It might not work out. On the other hand, from 105 AU, our sun is little more than a bright star in a background of dimmer stars. It's practically a pin-point as opposed to a circle. So it might not take an absurdly huge cloud to dim it, assuming the cloud and Andorlaine both orbit on the same plane.

[Martin Greywolf]

There really are two questions we keep answering here.

1) What would assorted lifecycles look like?

Unlike Earth, we don't have night and day, or strong seasons, that evolution can try to take advantage off, but at the same time, that doesn't per se mean there would be no cycles.
What would likely happen is a progression - at first, you get "once we get enough nutriets, we spread" cycles, and once those are established at whatever time you get, you start to have other lifeforms adapted to these cycles.

This creates the world where a reproduction cycle of a given flower dictates lifecycles of bees and insects and so on. While these wouldn't be of the same length mathematically, that wouldn't necessarily matter to a neolithic society. Since some of these cycles can be fairly small - perhaps there is an insect with lifecycle that happens within hours - you could end up with a system of time measure that is as utterly convoluted as imperial system is for length, since it is based on a variety of mostly unrelated measures in the nature.

2) How would an intelligent life solve its timekeeping needs?

Well, I have already mentioned measuring by lifecycles of plants. For a lot of things, that will do, but there will be attempts to measure time more precisely for a variety of purposes, mostly related to metalworking and pottery. And possibly rituals.

The solution for these has always been more or less the same throughout history - arbitrarily chosen clock.

The first possible clock is hourglass, but these are very hard to make, since they require either glass or crystal, sand of uniform fineness and precise manufacture. Not likely to happen.

Second clock is made using water. All you need for this is jars of the same size with the hole of the same size poked through them.

Third, there is fire. Take a material that can burn, make it of some length and thickness and then burn it. You can use a number of tricks to make the burn more uniform across several fireclocks.

This would create a world where various cultures and tribes have different measures of time, and if you go far enough, you may not even find the red flower you have in common to make the conversion. They only have blue flowers in these strange foreign parts.

[fusilier]

Now, in my earlier contemplation of this question, I did make one concession. There is a moon, a relatively late capture. This orbits once every six Earth-days, but though it appears about the same size in the sky as Luna to Earth, it's very small and low mass. (Tides is a difficult question, though it appears to impart about 94% of the acceleration Luna imparts to Earth, due to it's speed. It is assumed to be partly why the planet is not 100% completely tide-locked.) But that's nowhere near fundamental enough for the biology side of the question and aside from potential tides, the moon again won't be readily visible for an easy count even for a civilisation.

I'm confused: the planet has a moon. The moon has a regular cycle. The moon is about the same (apparent) size as the Earth's moon, but it's not visible? The Earth's moon can be seen during daytime.

If the moon is observable, and its cycle can be detected, then you would have the starting point of a timekeeping system.

On Earth, that starting point is the (24 hour) day. There are (or were) many different ways in which the day could be divided: equal hours, unequal hours, varying numbers of hours, etc. But the day was the cycle that all civilizations could observe.

For a civilization on this planet, I would expect the basis of time-keeping to be the moon cycle. They would have subdivisions based on the moon cycle, and other measurements based on X number of moon cycles having passed.

[Aotrs Commander]

How about a large cloud of dust that is at, say, 85-ish AU in a resonant orbit, and it blocks out the sun every couple-thousand years? Maybe a planet that was recently (a few million years ago) pulverized by a rogue planet from outside the system? I'm just spitballing here, so I don't know how much mass the cloud would need to block out the sun from 20 AU away, nor how long it would take to coalesce back into something that would no longer block the sun. It might not work out. On the other hand, from 105 AU, our sun is little more than a bright star in a background of dimmer stars. It's practically a pin-point as opposed to a circle. So it might not take an absurdly huge cloud to dim it, assuming the cloud and Andorlaine both orbit on the same plane.

That is, basically to best understanding, what causes the dimming of an RCB variable star.

Okay, for the record:

Andorlaine's star has a temperture of 6900K, mass 0.8 Sol, a diameter of 896.25 Sol and a luminoisity of 18818 Sol1. At 105 AU, with the effect of stabilising cloud feedback, it imparts a stellar flux of 2350W/m² to the planet (Earth's is 1367W/m²), giving an average of 3.9K warmer overall than earth (average, obviously the tide lock conditions means temperature range is more extreme). The greenhouse effect is extrapolated and interpolated from data located to be 29 (Earths is 33); the planetary albedo is 0.54, compared to earth's 0.3, likewise extrapolated from this paper here (https://arxiv.org/pdf/1307.0515v1.pdf)). The star has an apparent magnitude from Andorlaine of -26.78 (compared to Sol's -26.74) or -18-78 when dimmed (putting brightness about between the sun and moon on earth). The star has an angular diameter of 29.4' (compared to earth's sun and moon of 31.9' and 31' respectively). (At full strength actuial magnitude -5.85.)

The dust cloud is estimated to start at a radius of around 44 AU. (10 star radii, but looking at wiki, it might be double that if things have changed since I did the first pas in 2014, so might be 88 AU.)

Note that is would render anything close to the traditional tide-locking close distances impossible to support life, both because it would be within the dust cloud, and because the stellar flux would be enormous.



Basically, the astrophysics is pretty solidly fixed - I did literally spend months playing with it to get plausible values, with help from the physics forum - (and the world has appeared in "canon"), so unless better maths can be provided, that's all fixed at this point. (With the two unfortunate but necessary handwaviums (star duration and stellar wind dispersal) in place and left to "we don't know/magic/Anomalous Phenomena". (For star duration, possible explanations including Sufficiently Advanced Technology or direct connection to elemental plane of fire.))




I'm confused: the planet has a moon. The moon has a regular cycle. The moon is about the same (apparent) size as the Earth's moon, but it's not visible? The Earth's moon can be seen during daytime.

If the moon is observable, and its cycle can be detected, then you would have the starting point of a timekeeping system.

On Earth, that starting point is the (24 hour) day. There are (or were) many different ways in which the day could be divided: equal hours, unequal hours, varying numbers of hours, etc. But the day was the cycle that all civilizations could observe.

For a civilization on this planet, I would expect the basis of time-keeping to be the moon cycle. They would have subdivisions based on the moon cycle, and other measurements based on X number of moon cycles having passed.

Clouds. Due to the effect of stabilising cloud feedback raising the planetary albedo to keep the stellar flux to livable levels, it perform necessitates that a great deal of the light side (and probably the dark side) will be semi-permenantly covered by overcast clouds.

(I am taking a possible liberty in saying that the sky is EVER visible beyond the clouds, honestly, since that would in realit probably suggest a very sharp increase in surface temperature, but by the same token I work on the basis Weather Must Exist.)

It is, then, highly unlikely that the moon will be visible in the sky for the full period (less than three days, as it will move beneath the horizon) and then be immediately visible at the start of the next period with enoguh regularity that a neolitic society would notice it. That long a period of no cloud would likely be Extremely Bad for surface temperatures - or at least, in places where somethign disrupted the clouds, it would liekly form an extreme desert in the local area. (The tribe, who will be living on the edge of a swamp, surrounded by comaprtively low mountains, is not such an area.)

(In fact, the more I think about it, the less likely it would seem to be. More advanced civilisations would certainly have observed the cycle... But I am not dealing with those yet.)




There really are two questions we keep answering here.

1) What would assorted lifecycles look like?

Unlike Earth, we don't have night and day, or strong seasons, that evolution can try to take advantage off, but at the same time, that doesn't per se mean there would be no cycles.
What would likely happen is a progression - at first, you get "once we get enough nutriets, we spread" cycles, and once those are established at whatever time you get, you start to have other lifeforms adapted to these cycles.

This creates the world where a reproduction cycle of a given flower dictates lifecycles of bees and insects and so on. While these wouldn't be of the same length mathematically, that wouldn't necessarily matter to a neolithic society. Since some of these cycles can be fairly small - perhaps there is an insect with lifecycle that happens within hours - you could end up with a system of time measure that is as utterly convoluted as imperial system is for length, since it is based on a variety of mostly unrelated measures in the nature.

2) How would an intelligent life solve its timekeeping needs?

Well, I have already mentioned measuring by lifecycles of plants. For a lot of things, that will do, but there will be attempts to measure time more precisely for a variety of purposes, mostly related to metalworking and pottery. And possibly rituals.

The solution for these has always been more or less the same throughout history - arbitrarily chosen clock.

The first possible clock is hourglass, but these are very hard to make, since they require either glass or crystal, sand of uniform fineness and precise manufacture. Not likely to happen.

Second clock is made using water. All you need for this is jars of the same size with the hole of the same size poked through them.

Third, there is fire. Take a material that can burn, make it of some length and thickness and then burn it. You can use a number of tricks to make the burn more uniform across several fireclocks.

This would create a world where various cultures and tribes have different measures of time, and if you go far enough, you may not even find the red flower you have in common to make the conversion. They only have blue flowers in these strange foreign parts.

The repolies from the various places I posted this have ranged from "life would have no cycles at all" to "some sort of circiadian cycle would develop" and "creatures wouldn't ever sleep" to "intelligent creatues have to sleep to remove toxic build-up of neuro chemicals in the brains."

(One gentleperson on the physics forums seemed to think that life would be laregly entirely static consisting of nothing but climate specialists with nothing even capable of moigration to regions of differing light and climate levels; which I very solidly don't buy.)

So what I am largely getting is that is there is very likely no right answer.

I am leaning towards:

"Deepbreath" => approx two seconds and short measure (estimated from timed deliverate inhale/exhale)
"Babyfeeding" => modal period between feeding times for newborn babies (to be researched/estimated if possible from human babies maybe later, if I can claw back any time to do so)
and then possibly "weaning" (modal time to solid food) and possibly "gestation."

One gentleman rather disparaging suggesting that he thought I was too squeamish to use the menstrucal cycle, but I simply had not considered it, and that too, is under consideration.

I have considered and discarded artifical means of timing (like crops/burning sticks) etc. as too variable (and the village is primarily a fishing village - AND crops assumes that the tribe are not obligate carnivores, which is not a given at this point.) While water clocks are again, an obvious one for more advanced civilisations, a neolithic tribe feels unliekly to have developed them.

In addition, there is a reasonable arguement that the PCs will ahve to develop/improve their method of timekeeping as part of their oddessey as the tribe is forced to migrate.

However, as DM, I will of course need some base level of time-marking to track resource usages (and stuff like how long Things Last) - not so much spells to start with, but poison frequency, for example. A round being three deepbreaths and a minite 30 deepbreaths should be quite sufficient for at least the combat timings; "babyfeedings" will probably work in some increment for food resource comsumption intervals. Sleep and rest intervals are, as I say, largely whatever I choose to do, since there appears to be no real concensus. I will likely be using some of each answer; the tribe and other intelligent species (or at least some of them) might need a period of rest - as of this morning, I'm actually considering that effecticely trance (as elves) might be a neat approach and would make sense in context2. Meanwhile, lower lifeforms might not need that cycle and be able to rest their brains in stages if they need to at all.

Note that, however, the aforementioned is merely nominal; having had all the reponses, I do need to go away and have a proper think about it (something to do on my weekly walks) before I write up anything concrete.



1Statistics starting ballpark taken from R Coronae Borealis (https://en.wikipedia.org/wiki/R_Coronae_Borealis), the defining RCB variable star (https://en.wikipedia.org/wiki/R_Coronae_Borealis_variable), and adjusted for the appropriate amount of stellar flux primarily, and apparent magnitude and angular diameter secondarily (possibly, I forget, it might have just worked out neatly by semi-chance, given the stellar flux, in the same way the sun and moon are about the same apparent size by co-incidence). Because we know little about RCB variable stars, that basically HAS to be the basis for any even distant level of redibility, otherwise I might as well just make summat up. I'm already vastly pushing the boundaries by having the star last longer than it should (accounting for the fact we know very little about RCB variable stars), but that is going from at least something that has the rigth characterisitics to start with.

2One possibility this might even dovetail into I'm considering is that the PCs are effectively a fey-analogue. E.g. I lie and tell the players that the system has damage reduction equal to Con bonus, but it's ACTUALLY because they all have DR/[Cold Iron] or something. Or having them secretly be Tiny (and just zeroing the mechanics such that Tiny Is The New Medium). Both parts of the the effort to create a genuine air if paranoia and fear in the exploration (and stymieing the player's desire to metagame when they encounter remnants of former civilisations, because in a world where Magic Exists, the place Where The Stone Are In Unnatural Straight Lines (i.e. stone ruins) is spooky and avoided, but the superstition might be entiely justified if the ruins are actually haunted. Bare minimum, the first nonmagic sword they find (already Sufficiently Advanced Technology) is largely planned to have some sort of adverse effect on them (allergen at least) in order to drive the pont home that careful consideration and experimentation needs to be the way forward. However, both of the aforementioned options might be more effort than the gain of the reveal would be worth.

[Cactus]

This is a fascinating thread. For basic GM timekeeping I suggest you just use rations (ie number of meals eaten) as the measure of time. For example "You reach the <landmark> you were travelling to without incident, eating 6 meals each."

[Aotrs Commander]

This is a fascinating thread. For basic GM timekeeping I suggest you just use rations (ie number of meals eaten) as the measure of time. For example "You reach the <landmark> you were travelling to without incident, eating 6 meals each."

But that doesn't help me, since I need to know how long that is to calculate everything else (disease, inclement weather (i.e., likely meaning "it's NOT raining) etc; the same problem as using distance. It really does need to be measured by time. And me tracking it by 24-hours "days" and them not would incite confusion (and end up likely being accidently disregarded anyway leading to the players doing it too). Thus, a clean shift to difference system (with some level of relatively easy backward compatibility) is required for the practical reasons.

(From experience, I have to try quite hard to remember on my other campaign world to use the eight-day "quadmen" not the seven-day week, because not-Romans.)

[TexAvery]

if you do go with "extremely long day", one thing to consider is the concept that everything just moves along with the terminator. If we're talking around 1000 years for a single cycle, this is quite manageable, and could represent the concept that this one area would always be where life could survive easiest/best. People could form into nomadic tribes, who have travelled various routes (always going "east" or whatever), picking up every year or so and moving to the next valley.

The follow-up question for me is: what happens when the civilization gets to the equivalent of California and can't migrate further, squeezed by the creeping darkness against the endless ocean. Getting forced from the Great Plains over the Rockies wouldn't have been a picnic either. Unless the world is unending uniformity, those migrations would involve a lot more than just walking.

[fusilier]

But that doesn't help me, since I need to know how long that is to calculate everything else (disease, inclement weather (i.e., likely meaning "it's NOT raining) etc; the same problem as using distance. It really does need to be measured by time. And me tracking it by 24-hours "days" and them not would incite confusion (and end up likely being accidently disregarded anyway leading to the players doing it too). Thus, a clean shift to difference system (with some level of relatively easy backward compatibility) is required for the practical reasons.

(From experience, I have to try quite hard to remember on my other campaign world to use the eight-day "quadmen" not the seven-day week, because not-Romans.)

From a game mechanic point of view, *I* would be worried about confusing/frustrating my players with too complicated a system! Nevertheless, I have found this a fascinating thread!


(In fact, the more I think about it, the less likely it would seem to be. More advanced civilisations would certainly have observed the cycle... But I am not dealing with those yet.)

Ok, that makes sense. Yeah, so you're looking for what kind of cycle might be steady enough, and sufficiently universal, so that different tribes would have a common time measure. (Honestly, I don't know what I would use, if astronomical events aren't sufficiently observable). My main point was that on Earth the basis for time keeping was the day, and other time measurements were made up either by dividing the day or grouping consecutive days together. You just need to find some sort of similar, regular, and recognized cycle.

However, there were other, more subjective ways, used to measure a short amount of time: based upon an experience of some sort. So you might hear descriptions of earthquakes lasting for as long as it takes to say a particular prayer. Sometimes with qualifiers, like "recited very slowly," or "one and a half times."

Then there were the distance-time measures: "the meeting bell is to be rung for the amount time it takes a person to walk a mile at a moderate pace." These experiential based time measurements were all very subjective, and often highly localized, but in their time they were considered relatively precise measurements. Going from that environment to a modern one, where people describe time very accurately with clocks, can obviously be problematic.


"Deepbreath" => approx two seconds and short measure (estimated from timed deliverate inhale/exhale)
"Babyfeeding" => modal period between feeding times for newborn babies (to be researched/estimated if possible from human babies maybe later, if I can claw back any time to do so)
and then possibly "weaning" (modal time to solid food) and possibly "gestation."

These concepts kind of fit with those ideas of experiential time measures. Breathing varies with activities, so terms like "at rest" might be needed to clarify.


While water clocks are again, an obvious one for more advanced civilisations, a neolithic tribe feels unliekly to have developed them.

Honestly, I think you would have trouble with time if you were running a game with a neolithic society on Earth. You could say how many days had passed. But if you saw the enemy approaching the town, and it would take about 15 minutes for them to reach the town: *you* might have a sense for how long it was, but you couldn't communicate it as a "time" as we understand it. (You're not going to say, they'll be here in about 1/96th of a day). Instead, you would communicate it as: "they're less than a mile away."* People would have a sense, of how fast a war party could travel, but they couldn't express it in a precise "time".

Most of the historic information I have about the development of timekeeping comes from a book called "History of the Hour" -- while the book covers many different themes, one of them is how the increasing accuracy of clocks, led to a change in how people viewed time, and how they structured society. In the early middle ages if you agreed to meet a friend in a field at noon: you might show up half-an-hour before noon, and your friend half-an-hour after noon. Things like that just happened, and it wasn't an issue -- few things were timed that precisely.**

In this sense, maybe just abstract it? The length of a round is the amount of time it takes to do all the stuff that you can do in a round. If there are certain GM controlled events that happen at certain times, then you can keep track of seconds/hours/days, or whatever. The players just need to know that certain events have passed, not how much time has passed? Those *events* can include recuperating, etc.

(You can use distance-time measurements if you really want to, but they can sound really weird to modern people. If the road was really difficult it might take you "five miles to go two miles").

*Or, if you haven't developed distance measurements (and honestly I'm not sure when they developed), you might say, "the enemy is at the creek north of the village."

**If you wanted to time something more precisely, you had to provide a signal. For example, tolling a bell. This is why we have statements about how long to ring the bell -- when the meeting bell had finished ringing, everybody was expected to be at the meeting place.

[Rav]

Give it a ring and have it complete a rotation around its star every day. The shadow of the ring will keep time perfectly.

[Psyren]

Starfinder has a tidally locked planet you can use for inspiration: Verces. When they absolutely need to, they measure time by tracking the subtle motions of distant stars, but most often they just track their schedules by local or familial needs.

[gbaji]

But that doesn't help me, since I need to know how long that is to calculate everything else (disease, inclement weather (i.e., likely meaning "it's NOT raining) etc; the same problem as using distance. It really does need to be measured by time. And me tracking it by 24-hours "days" and them not would incite confusion (and end up likely being accidently disregarded anyway leading to the players doing it too). Thus, a clean shift to difference system (with some level of relatively easy backward compatibility) is required for the practical reasons.

Why not just define everything in the game in terms of whatever time unit you choose? I guess I'm confused at your confusion. For "in character" measurements, most things (especially things like weather, major events, etc) could certainly be measured in multiples of "eatings" or "sleepings" or things like "short tasks" (time taken to go to the bathroom, or go to the well for water, or whatever) and "long tasks" (time to milk all the cows, or write a letter or something similar). Time measurements do not need to be accurate, nor would they be expected to be. As a couple posters have pointed out, prior to the invention of consistent/accurate mechanical methods of time, people just estimated, and were often off by significant amounts of time, but it didn't matter. If you agree to meet someone in X time, you go there when you think X time has passed, if the person is there, great. If not, you wait until the other person arrives. There aren't a whole lot of things that less technologically advanced civilizations do that actually need accurate timekeeping (at least not on a shortish scale like minutes).

Again. Assuming that people do need to eat and do need to sleep, then cycles of those things are plenty accurate enough for longer scale events like weather, planning migrations/travel, hunting, exploring, etc.


And for game mechanic stuff, if your game uses "rounds" for calculating actions in the immediate time frame, just use rounds. You don't need to define how long a round is in earth time. One round is the time it takes to perform one major action, or two half actions (or whatever your rules use). Who cares how many seconds that is? Doesn't matter. For game situations where this matters, then you just tell them "It'll take 3 rounds to do X". Done.

Are you trying to resolve a philosophical question, or building a workable system for a game?

[Jay R]

This is a difficult question, but it comes long after the real difficult question.

Every species we have ever known, except those in caves or very deep in water, has been subject to the changes of the day and the changes of the season. What would a species be like that wasn't?

What would its sleep cycles be like? What would plant life be like with no seasons? Presumably there would be no hibernation, no migrations, no nocturnal species. We have no idea how life would develop with no cycles imposed by the planet.

First we would need to solve the question of what kind of creatures could develop in such conditions. Once we knew what they were like, it might be possible to determine how they would measure time.

[Storm_Of_Snow]

For the original question, the planet itself may still be rotating even though it's tidally locked, but along its orbital path rather than parallel to it, so you'd have some idea of a day by seeing the stars above/below the orbital plane - Neptune behaves in a similar manner, although it's tilted onto it's side and not tidally locked, and basically rolls along on one side of the orbit and back spins on the other.

For a year, again you can pick one or two stars, and note when they're directly away from the sun.

If there's a satellite, you'd get regular tides, there might also be some kind of terrain feature that gives a roughly regular event that could be used for timing. This could be something like a geyser or possibly something more exotic.

And then there's manufactured units rather than natural ones - for instance, you might have the smallest regularly used unit of time that's based simply on how long it takes an object to fall from a certain height.

[Hytheter]

Neptune behaves in a similar manner, although it's tilted onto it's side and not tidally locked, and basically rolls along on one side of the orbit and back spins on the other.

I believe you're thinking of Uranus.

[Storm_Of_Snow]

I believe you're thinking of Uranus.
Of course I am, apologies all.

[Azuresun]

that's my main issue. a star so big must be a blue supergiant, and those last only a few tens of millions of years. but this level of detail, i'm generally willing to handwave

Maybe it's not one star, but actually a contact binary (https://en.wikipedia.org/wiki/Contact_binary) (two stars orbiting so close that their atmospheres merge) that collectively has the same brightness and gravity as a hypergiant? The stars orbit each other so closely they appear to be one body from the point of view of any planets.

[BloodSquirrel]

I think you're approaching this from the wrong end.

The reason we think about time the way we do is because the day/night cycle and seasons exists. It makes sense for us to work during the day and to sleep at night. It makes sense for plants to have have life cycles that involve blooming during the spring when it's getting warm. And since we evolved with the day/night cycle, we continue to run on an internal clock that reflects that, even when in an artificial environment.

Without the day/night cycle and the seasons, life would not structure itself around those cycles. We would either sleep irregularly as events made it convenient to, or we would evolve to sleep on some cycle that was biologically optimal, rather than one based on some external phenomenon, or we might not evolve to sleep at all. Plants would simply grow at a constant rate, producing seeds without the need to synchronize themselves to non-existent weather patterns.

As human civilization advanced, and the need for wide-scale coordination created the need for some form of time keeping, different forms of "clocks" could be created that would give appropriate approximations. These clocks would be based on the nature of the need itself; if a town simple needed to keep work schedules on track, any form of hourglass (You can do the same with with a tank of water with a hole in it for larger time intervals) could be located centrally in the town.

Instead of looking for a general solution to the problem, look for how each individual problem could be solved most naturally.

Case in point: How do you tell how old somebody is? Well, do you really need to? Instead of "age", people's maturity is measured by life events. A girl because mature when she has her period. A boy becomes mature when he passes some kind of ritual or test. Instead of retiring at a specific age, people retire when they've achieved some socially relevant goal.

[Lord Torath]

Just a minor point. Aotrs Commander has stated a couple of times now that the reason the stars and moon are invisible is because there's a more-or-less permanent storm covering the bulk of the sun-facing side of the planet. Hot air rises under the sun, flows at high altitude around to the night side of the planet, cools and sinks, then flows back at low altitude to the sun-side.

So the moon, even though it takes up the same amount of sky that ours does, is pretty much never seen on the day-side of the planet. Certainly not regularly enough that its cycle can be tracked. The stars are obviously not seen on the day side, and since the adventures all take place on the day side, it doesn't really matter if they can be seen from the night side.

[Quertus]

But that doesn't help me, since I need to know how long that is to calculate everything else (disease, inclement weather (i.e., likely meaning "it's NOT raining) etc; the same problem as using distance. It really does need to be measured by time. And me tracking it by 24-hours "days" and them not would incite confusion (and end up likely being accidently disregarded anyway leading to the players doing it too). Thus, a clean shift to difference system (with some level of relatively easy backward compatibility) is required for the practical reasons.

I’m confused.

So, there are at least 2 competing points of view? Time as viewed by the natives, and time as viewed by the players/GM/game system?

Also, potentially whole new species (specieses?), and I’ve heard the word “magic” used?

OK. So… why not give the species an innate ability - perhaps even a useless one - that lasts a handy amount of time? One “glow” (one activation of photo luminescent) lasts or an hour or whatever. One puff (one activation of filling their air sack) lasts a turn.

Being by the lake, they *will* notice the tides, and will have tide-based time words… and, likely, corresponding societal structures, like a “meal” or a “rest” corresponding to a tide shift? Hmmm… at a 6 day rotation, that’s a high tide every 3 earth days. So a “lake filling” might measure 3 rests and 6 meals… or 6 rests and one meal, depending on the biology involved.

Speaking of biology, on the flip side, will your new life forms even have breast feeding, menstrual cycles, puberty, and other such familiar things, to be used as metrics? Imagine a species that doesn’t “cut the umbilical” until the young are old enough to eat on their own… and whose young are born reproduction-capable.

And, while we’re discussing alternate biology, why not measure time in “sheddings”, for a serpentine race? Or how about a race that grows new teeth every 70-80 lake cycles, forever, and declares their age accordingly as “5th tooth”?

Of course, if they have magic (like sorcerer’s spells), then the duration of those spells might well be the basis of their timekeeping.

The (muggle) cultures I envisioned as I read this thread might be a bit more advanced than you intend, as some measured time by fields and fermentation cycles, but for simpler things, I very much like the idea of using plants / blooms to measure time. “When this blossom falls, the meat will no longer be good”, “the closest village is over two blooms away”.

Or just be a Hutt, make everything food based, and say that the nearest village is 12 meals away.

I’m… not seeing a simpler system than just making your unit of time and distance be the meal, tbh. What is the downside to doing so?

[Palanan]

Originally Posted by Aotrs Commander
While water clocks are again, an obvious one for more advanced civilisations, a neolithic tribe feels unliekly to have developed them.

I wouldn’t rule out the water clock so quickly. As noted above, in its simplest form it’s just one pot draining into another, and it’s easy to imagine different-sized pots measuring different quantities of time.

Why do this at all? I can think of two reasons right off. First, games. Structured play is part of all human cultures, and I wouldn’t imagine it would be any different for the sapients on Andorlaine. Games are more exciting with tension, and adding a time limit helps to generate tension. Can we score before the time is up? Can we beat them before the water runs out? It only takes one individual to come up with this idea, and you’ve got the beginnings of structured time.

Why else to use it? Cooking. Neolithic people like a good meal like anyone else, and it only takes one individual to work out that food is better when it’s cooked just so. Working out how long to cook a particular fish so it melts in your mouth (or your ukkiz-sacs) is just the sort of thing that cries out for specific measurements of time. “Cook it over a low fire for two small water-pots per side, add some ground jassa-dust and you’ll swoon.”


Originally Posted by Aotrs Commander
It is, then, highly unlikely that the moon will be visible in the sky for the full period (less than three days, as it will move beneath the horizon) and then be immediately visible at the start of the next period with enoguh regularity that a neolitic society would notice it.

On the contrary—if anyone will notice this, it’ll be individuals in a neolithic society, living closer to the earth and more aware of the sky and its motions than any others. Best example is Classical Mayan culture, who developed highly sophisticated astronomy and cosmology centuries before any real metallurgy developed.


Originally Posted by Aotrs Commander
The difference between 100% tide-locked and "maybe moves a fraction of a millimetre every few centuries" is largely academic, I feel.

It’s not, and in fact I would say it’s vital to understanding all life on this world.

What you’re describing is roughly on a par with the timeframe of continental drift, and ask any continent—especially Australia or Antarctica—if slow drift into hostile latitudes hasn’t affected its flora and fauna.

On timescales of millions of years, regions of Andorlaine which had been on the dayside will drift through the twilight ring and they will become part of the nightside. Meanwhile regions of the nightside will drift in the opposite direction into the dayside. That is a fact of the dynamics as you’ve laid them out, and it will have profound effects on the evolution of biota on this world. Not addressing this is as significant as not addressing any of the astronomical variables that you’ve already meticulously worked out.


Originally Posted by Quertus
OK. So… why not give the species an innate ability - perhaps even a useless one - that lasts a handy amount of time? One “glow” (one activation of photo luminescent) lasts or an hour or whatever. One puff (one activation of filling their air sack) lasts a turn.

Really good ideas here. And I endorse the inclusion of tide-based vocabulary.

[Jay R]

A related question. Many game mechanics (I'll use D&D as my example, but it applies to many others) assume the rhythms of time here on Earth. Should any rules be changed for a planet that doesn't match?

Does a caster need eight hours of sleep? Why? When do lycanthropes change automatically? Do spell effects last in hours or minutes? Again, why? How long does Persist Spell make a spell last?

In short, the biorhythms of an planet with earthlike time measurement are assumed by most most game systems.

[Quertus]

A related question. Many game mechanics (I'll use D&D as my example, but it applies to many others) assume the rhythms of time here on Earth. Should any rules be changed for a planet that doesn't match?

Does a caster need eight hours of sleep? Why? When do lycanthropes change automatically? Do spell effects last in hours or minutes? Again, why? How long does Persist Spell make a spell last?

In short, the biorhythms of an planet with earthlike time measurement are assumed by most most game systems.

Persist Spell makes a spell last one day, which, on this world, is thousands of (Earth) years, longer than the campaign or the caster will likely last. Lycanthropes change at sunset of a full moon, so you’d best be able to see the moon when you cross into the dark side (Although it’s hinted that this is a thing they’re evolved to do, so probably *everyone* is secretly a breed lycanthrope, with DR 15/Ag).

[Lord Torath]

Being by the lake, they *will* notice the tides, and will have tide-based time words… and, likely, corresponding societal structures, like a “meal” or a “rest” corresponding to a tide shift? Hmmm… at a 6 day rotation, that’s a high tide every 3 earth days. So a “lake filling” might measure 3 rests and 6 meals… or 6 rests and one meal, depending on the biology involved.I'd forgotten the tidal effect of the moon on the world. Yes, large bodies of water will definitely experience tides, and they will be substantially stronger than Earth's tides. Remember that the tidal force goes by one over the distance cubed, so if the moon is twice as close, the tidal forces will be 8 times as strong. Of course, the mass of the moon is a good bit less than the mass of Luna*, so that will mitigate it somewhat.

Okay, let's do some math: to maintain the same apparent size, if it orbits half as far out as Luna, it would need a diameter half of Luna's, which means, assuming the same average density, it would have 1/8th the mass. (This is completely ignoring orbital mechanics and whether or not a moon half the size of Luna orbiting half as far out would really complete an orbit in 6 days. I'm only interested in the relative tidal forces in this calculation.)

Quick visit to wikipedia (https://en.wikipedia.org/wiki/Tidal_force#Sun,_Earth,_and_Moon)

In the formula, "m" is the mass of the body exerting the tidal force (the moon and Luna in this case), and "r" is the radius of the body experiencing the tidal force, in this case Andorlaine. Assuming it's about the same size of Earth, that value will not change. So with 1/8 the mass and 1/2 the distance cubed, those terms cancel out, and in fact, Andorlaine and Earth will experience the same tidal forces from their respective satellites.

So assuming the same density for both moons and the same apparent size in the sky, the tidal forces will be identical. Interesting. They'll just last much longer on Andorlaine, since it doesn't rotate under the moon the way Earth does under Luna.

* Is "Luna" the proper name for Earth's moon? Don't know, don't care. For the purposes of this discussion, it makes it easier to distinguish between Earth's moon and Andorlaine's moon. For a detailed discussion on the subject, kindly take it to a different thread.

[TexAvery]

A related question. Many game mechanics (I'll use D&D as my example, but it applies to many others) assume the rhythms of time here on Earth. Should any rules be changed for a planet that doesn't match?

Does a caster need eight hours of sleep? Why? When do lycanthropes change automatically? Do spell effects last in hours or minutes? Again, why? How long does Persist Spell make a spell last?

In short, the biorhythms of an planet with earthlike time measurement are assumed by most most game systems.

In this particular case, the moon is there but behind clouds, yes? Lycanthropes could switch on moons they can't see, which would make it scarier.

Separately though, that would also allow "changes" to be used as a unit of time, if this were a world with lycanthropes.

[Thunder999]

Track rations and speed in RL hours, mechanical rounds etc. and have it be tied to how often they need to eat?
How often that is is mostly up to you.

[Bohandas]

If they live on or near the night side they could measure the passage of years by the stars

[Asmotherion]

In this example, I assume your "alien" lifeforms have at least some things in common with life as we know it. I'm also assuming seasons happen despite the tidal lock, as for example the moon does experience mild seasons, despite being tidally locked.

Observing plant life; When everything starts Blooming, the year starts, and when everything starts withering, half a year is gone.

Observing the Weather; Assuming there are seasons, there will be at least some form of deviation of the temperatures.

Observing Animals; Hybernation cyrcles and the time needed to rest can be a way to measure time, to mention just some examples.

If the planet has a moon, the rotation of the moon around the planet could be a unit.

[Bohandas]

* Is "Luna" the proper name for Earth's moon?

It might be "Theia" depending on if the Giant Impact hypothesis is correct and what your opinion of the Grandfather's Axe/Ship of Theseus paradox is

[Lord Torath]

It might be "Theia" depending on if the Giant Impact hypothesis is correct and what your opinion of the Grandfather's Axe/Ship of Theseus paradox isYou must have missed the rest of the footnote:
* Is "Luna" the proper name for Earth's moon? Don't know, don't care. For the purposes of this discussion, it makes it easier to distinguish between Earth's moon and Andorlaine's moon. For a detailed discussion on the subject, kindly take it to a different thread.Let's keep this thread on topic.


In this example, I assume your "alien" lifeforms have at least some things in common with life as we know it. I'm also assuming seasons happen despite the tidal lock, as for example the moon does experience mild seasons, despite being tidally locked.

Observing plant life; When everything starts Blooming, the year starts, and when everything starts withering, half a year is gone.

Observing the Weather; Assuming there are seasons, there will be at least some form of deviation of the temperatures.

Observing Animals; Hybernation cyrcles and the time needed to rest can be a way to measure time, to mention just some examples.

If the planet has a moon, the rotation of the moon around the planet could be a unit.I'm unfamiliar with the lunar seasons. Do we know what causes them? Are they driven by the angle of Luna to the sun? How long are those seasons? My admittedly quick google searches are turning up the opposite, that Luna has no seasons.

For the tidally-locked Andorlaine, if the seasons are driven by proximity to the sun, then seasons would be on the order of 250 earth years long. We are operating on the assumption that life forms on the planet live about as long as life forms do on Earth, which means that a season lasts 3-4 times longer than the average lifespan of a person. Not really a great way of measuring time on a 'day-to-day' basis.

Using the moon is fine, but the sunward-side of Andorlaine is covered in near perpetual cloud cover, so the moon is almost never visible. It's effects on the tides is certainly something to pay attention to if you're near an ocean, but if you only have a mid-sized lake, it becomes harder to notice.

Question: how wide does a body of water need to be to have noticeable tides?

[Aotrs Commander]

Seasons are a function of both axial tilt and orbit eccentricity. As Andorlaine is fundementally tide-locked, it means that the planetary axis is 90º - so at all points of the orbit, a given sunside location recieves the same amount of sunlight, and also that the orbit has very little (if any) eccentricity; so neither of those aspects will create any meaningful seasons. (The analogue to seasonal change is instead the dimming periods, and those are both more erratic and by the standards of a mortal creature, further apart than civilisations.)

[Lord Torath]

Question: how wide does a body of water need to be to have noticeable tides?Looks like Loch Ness (35 km long) has a 1.5 mm tide, measured to the nearest 0.1 mm (BBC: Loch Ness is giant 'spirit level' (https://www.bbc.com/news/science-environment-16394421)). Depending on what "noticeable" means, you're going to need a pretty big body of water to track the tides every 6 days.

[Septimus]

Coming from an astrophysics background, I find this thread really interesting.

For the star duration (less than 100 millions years approximately as a yellow supergiant), I do not see another way than to hand wave the problem to either magic or advanced science (which are equivalent concepts). Close binary would mildly increase the duration, as two stars with equivalent summed luminosity will still be massive stars and the billion years of life expectancy is nowhere close. Furthermore, the OP seems to be locked on a RCB star, which is fine as it includes some interesting facts for the stated problem.

RCB stars are variable stars, with two modes of variability : one with small amplitude and quite predictable, and another with higher amplitude but quite unpredictable. These should be taken into account when we are considering the life forms that evolved on the planet and how to measure time.

The small but regular amplitude should be the basis of the time passing. For most RCB stars, it looks like the period is several tens of days, but with the cycle you might infer that it is measurable and take into account by observer to measure the time to pass. Up to you to define a convenient time, but a 28-day period is probably the right thing to catch-up on Earth equivalents. Then you can easily split it into 4 "weeks" of ascending/high/descending/low period of "sun", corresponding on weeks. Even if the sun is obscured by clouds most of the time, though time and observation, it is possible to find out these periods and implement them into a civilisation. For the shorter "day" period, I think the only solution would be to be based on the moon orbit, which might be noticeable, or calculated through an ephemeris. You can have something close to a day with that.

The second mode would impact the equivalent of seasons. The impact of a dramatic change of lights, and for an unknown length of time, would trigger various life events for the life form: plant-based life forms would induce fruition and possibly winter sleep, and animal-based form would follow this cycle with rampaging feeding at the beginning of the decrease and possible hibernation for several large creatures. Humans, or equivalent, would probably create mythologies around this second cycle, with dramatic measures to keep everyone alive. The possibility of winters that spans across years in between "summers" that last decades is in fact a very similar setting than the Iron Throne (btw, a colleague of mine tried to find a astrophysics case that would match that and a few issues, but you could hand wave the minor details).

Life forms would have different sleep pattern, most probably using tricks to have functioning body for a longer period of time, such as a brain would have halves work in cycles, one half working as the second half is resting, and then the reverse. Dolphins use this tricks for the their sleep if I remember correctly, and you could expand this to most life forms: animals would have a "quiet period" when each half is resting, with limited activities but still active. Humans could evolve in the same pattern, creating the need of period of time where they are "not here" but still active nevertheless. It would be similar to a early version of elves who never sleeps but meditate to recover their capabilities.

The revolution time of the planet would be irrelevant, as stars observation would be difficult, and the length is too long to be measure for short-lived creatures. But elfes and similar creatures might have such a long cycle and use it as their "racial" calendar to keep tracks of lasting events. Short-lived creature might then be aware of this cycle, and care about it (mostly in religion I guess), and ignore it completely.

Then, finally, there the question of the night face, and the wind it should create. Strong winds, equivalent to hurricane or more, should be common. It is the necessary requirement to have a functioning atmosphere on all the planet: the night face should be freezing cold, and even gas may condense if it is too cold. Wind may ensure a mixing between the two faces and distribute heat and cold. Night face would be still very cold, but not necessary to the point where nitrogen would become liquid. Atmospheric models may compute the necessary exchange rate, but it would be easier to have a working model, such as constant strong wind, with possibly period of very intense winds. That would impact the architecture of advanced civilisation, with strong foundations or caverns used as emergency covers. With a slow rotation, and hence small angular momentum, you will not have a strong dominating direction but then the system would be more complex, and unpredictable for the intelligent life forms.

[Aotrs Commander]

Coming from an astrophysics background, I find this thread really interesting.

For the star duration (less than 100 millions years approximately as a yellow supergiant), I do not see another way than to hand wave the problem to either magic or advanced science (which are equivalent concepts). Close binary would mildly increase the duration, as two stars with equivalent summed luminosity will still be massive stars and the billion years of life expectancy is nowhere close. Furthermore, the OP seems to be locked on a RCB star, which is fine as it includes some interesting facts for the stated problem.

Ultimately, it was the most approximately plausible basis for the concept of a nonpredictable period of extended solar dimming (i.e. a an extremely long "night"); still entails handwaving, but it was the "best fit."


RCB stars are variable stars, with two modes of variability : one with small amplitude and quite predictable, and another with higher amplitude but quite unpredictable. These should be taken into account when we are considering the life forms that evolved on the planet and how to measure time.

The small but regular amplitude should be the basis of the time passing. For most RCB stars, it looks like the period is several tens of days, but with the cycle you might infer that it is measurable and take into account by observer to measure the time to pass. Up to you to define a convenient time, but a 28-day period is probably the right thing to catch-up on Earth equivalents. Then you can easily split it into 4 "weeks" of ascending/high/descending/low period of "sun", corresponding on weeks. Even if the sun is obscured by clouds most of the time, though time and observation, it is possible to find out these periods and implement them into a civilisation. For the shorter "day" period, I think the only solution would be to be based on the moon orbit, which might be noticeable, or calculated through an ephemeris. You can have something close to a day with that.


The second mode would impact the equivalent of seasons. The impact of a dramatic change of lights, and for an unknown length of time, would trigger various life events for the life form: plant-based life forms would induce fruition and possibly winter sleep, and animal-based form would follow this cycle with rampaging feeding at the beginning of the decrease and possible hibernation for several large creatures. Humans, or equivalent, would probably create mythologies around this second cycle, with dramatic measures to keep everyone alive. The possibility of winters that spans across years in between "summers" that last decades is in fact a very similar setting than the Iron Throne (btw, a colleague of mine tried to find a astrophysics case that would match that and a few issues, but you could hand wave the minor details).

That is the high-concept of the world. It was partially inspired by (which I can now address directly since someone was able to idenfiy it) the Third Doctor Serial the Mutants. Basically, from the standpoint of a civilisation, that darkness would fall, the world would change around them in terrifying ways and they would be suddenly dealing with an influx of monsters (apparent and actual) coming from the night side. The conciet being that the periods between as of sufficient space that when it occurs, it fundamentally ends the civilisations, which never have developed to cope with them. (The very early concepts were an evenstar; a world whose metaphorical "fantasy novel series" would be at the twilight (both literal and metaphorical) of their civilisation, as it is overrun by the thing Things from the Darkness.)

As this is an entirely alien camapign world, elves as such do not exist, and by definition of the central concept, the races which develop civilisations cannot be long lived enough to retain living memory. Thus, there is a world strewn with runs of previous, unknown civilisations. The most advanced of these is tentatively placed slightly beyond 21st century Earth (pre-FTL and pre-space colonisation); just not quite advanced enough to survive such a Bad Happen.

(The idea of the paleolithic tribe and their campaign - the Long Walk - their migration across the world, along an ancient road (something they barely undestand) came later. Part of the appeal of that scenario is to have a people so primative that it can capitalise on using player ignorance of the setting to make for better exploration in a way you can't do otherwise.)



Life forms would have different sleep pattern, most probably using tricks to have functioning body for a longer period of time, such as a brain would have halves work in cycles, one half working as the second half is resting, and then the reverse. Dolphins use this tricks for the their sleep if I remember correctly, and you could expand this to most life forms: animals would have a "quiet period" when each half is resting, with limited activities but still active. Humans could evolve in the same pattern, creating the need of period of time where they are "not here" but still active nevertheless. It would be similar to a early version of elves who never sleeps but meditate to recover their capabilities.

I have decided, in the event, to tackle this by having many creature have a continuous cycle, but for sophont lifeforms in particualr, to have a period of, if not sleep, perhaps something closer to elven trance; not quite torpor, but, like, you say, a quiet period on significantly reduced activity. (While their brains clear all the neurotoxins.)


Then, finally, there the question of the night face, and the wind it should create. Strong winds, equivalent to hurricane or more, should be common. It is the necessary requirement to have a functioning atmosphere on all the planet: the night face should be freezing cold, and even gas may condense if it is too cold. Wind may ensure a mixing between the two faces and distribute heat and cold. Night face would be still very cold, but not necessary to the point where nitrogen would become liquid. Atmospheric models may compute the necessary exchange rate, but it would be easier to have a working model, such as constant strong wind, with possibly period of very intense winds. That would impact the architecture of advanced civilisation, with strong foundations or caverns used as emergency covers. With a slow rotation, and hence small angular momentum, you will not have a strong dominating direction but then the system would be more complex, and unpredictable for the intelligent life forms.

That part I did get (the night side having a large ocean was also in part because what I had read was that would liekly be a further temperature stabilising factor.)

You can see some of that applied in the so-far brief data compiled (written as an in-universe study by the Aotrs, as it might eventually be used as an entry in Bleakbane's Galaxy Guide (https://forums.spacebattles.com/threads/bleakbanes-galaxy-guide-aotrs-shipyards.1002253/) with the sailed hover shells. (Italics indicate a placeholder name for the moment.) Yes, the first creatures that were created for Andorlaine were magical, in defiance of concept, but partically, the hover shell is an nod to a picture I drew when the idea of an entirely alien campaign world came to me decades ago and comb jellies were the inspiration for the creatures the Aotrs party would encounter on their sojourn there. (And incidently, providing a disconnected, but in-universe perspective to write about the world with comparatives.) That it enabled me to encompass the demon brains in the same group was icing on the cake.


Scaled Jellies: Subphylum of endothermic creatures with radial symmentry around twelve ribs joined at the bottom of the creature (or top, in the case of the shelled flyers). They have six arms, morphologically closest to those of cephalopods, though the suckers are signficantly smaller, denser and finer and not as readily apparent.

Believed to be initially aquatic with covergenant morphology to comb jellies, the phylum is theorhised to have developed scaley and then scutted skin and bones in tandem; the bones allowing heavier scutes to be mounted. It is not currently clear whether or how the scutes are shed, but it is theorhised to be accomplished in a manner analogous to terrestrial turtle or crododile shells is they are shed; they may be retained throughout the lfie like some dragon species, but this is not through to be as likely. The anchoring of the skeletal structure allows more powerful musculature, predating via harpoon-tipped arms rather than complete reliance on stinging cells; the harpoons in many forms are armed with apparatus which appears to have functioned somewhere between a stinging tricome (i.e. a stinging nettle sting) and a nematocyst (i.e. a jellyfish/comb jelly/ anemone cell). Monster brains retain only a vestigial harpoon/sting (analogously equivalent to a more reinforced fingernail) while ghost jellies appear to have lost the harpoon entirely, but retained the sting.

Single mouth/excretory oriface (dorsally located); some waste products “sweated” out via pores. On magical floating forms, “nostrils/breathing apapratus” are located around the mouth, leading to six lungs, more primative marine forms have gill openings here, but which are likewise provided with water flow by breathing-like pulsations of proto-lungs.

Single muscular “foot” at bottom of ribs allows very slow ground locomotion and also serves as a holdfast.

Primary sense appears to be vibrational/hearing via an advanced system of lateral-line-like mechanoreceptors and electroreceptors located across the entire body surface. In combination with additional organ sensors, these grant a high kinesthetic sense. Six antennae (fillamented/feathered) appear to serve as a directional olfactory system and also may act as supplementary mechanoreceptors. Skin receptors on the skin and on the surface extremely developed tacile sense.

Vision is a secondary sense, provided by a series of eyespots, two rings, one between each rib segement on marine forms. On magical floating forms, at the front of the creature, a slight bulge houses additional eyespots on the upper ring, forming a diamond pattern with the top-most eyespot being part of the ring. Shelled flyers instead have developed more acute vision, transforming front two eye spots into eyes on rectractable stalks and losing the rest of the upper ring, while the lower eyespots have become centrally-located around the creature’s centre. Eyespots, while relatively simple (having no pupils) apparently have some ability to distinguish colour on some level, as evidenced by bioluminent nodules running down the line of the ribs and in some form, tentacles. Shelled flyers (observed) and monster brains appear to have relatively few of these nodules and use them infrequently. (Though it is speculated that shelled flyers may use theirs more frequently when mating.)

High animal intelligence observed in marine forms (approximated at canine- to octopus- perhaps higher) and lesser demon brains. Ghost jellies are sophont; demon brains are expected to be both sophont and highly intelligent from the differences in their morphology from the lesser demon brains. This is likely an emergant property of the complex nervous system created by the numerous, decentralised sensory organs. (This complexity is also potentially a cause of the evolution of the magical flight organs in the magical floating forms.) Shelled flyers, which appear to generally have more specialised diets, appear to show generally lower intelligence, especially in non-predatory forms; though not enough samples have been studied to say whether this is consistently true of their entire order.

Magical floating forms possess two organs at the rear which provide magical locomotion via levitation. Flight is suggested to have possibly developed as a method to escape predators in the acquatic environment (as terrestrial flying fish). These organs appear to have lost their original function in the monster brains, being re-purposed to service the eusocial controlling magics.

Shelled flyers have developed scuted skin into a hard shell. The mouth is now located on the ventral side; locations of organs suggest indicates that they evolutionarily inverted their body plan as they adapted to flight. Sailed hover-shells additionally have adapted two pairs of tentacles with webbing between that act as a retractable sail, allowing them to move downwind with significant ease; notably these forms with their reduced arms appear to be predominatly non-predatory.

Ghost jellies appear to have lost their scaled scuttes altogether, leaving only thin skin. This may or may not be translucent or semi-translucent. The ghost-like form encountered appeared to have translucent skin, but no living specimen has been observed. The observed deceased specimen’s skin was not translucent, but may have opaqued with mummification.

[Septimus]

You seemed to have studied your case a lot lol ;) I had assumed a nearly human life form for the exercice, so several of my comments might not apply for a "too-much" alien life form.

One of the things to be taken into account is that the "nights" are actually unpredictable in length but also in magnitude. You can imagine to have "winters" that last a few months with still light as the sun is on low power but still visible, and winters that last years of blackout darkness. A daylight civilisation might endure several winters before "The One" that destroys everything and press the reset button. That would create even more myths about the "darkness that destroy".

Also, as light is nearly always present on the daylight half, sight would be the most useful sense for animals, and a drop in the ambiant light would have more effects on the life forms than on our world where a large fraction of the animals are nocturnal. Adaptation of night vision would be extremely rare, and reserved to subterranean species, invaders from the night side, or specific species from the penumbral circle.

Large oceans are indeed a stabilisation factor, whereas they are in the night or in day faces. It makes sense to have most of the night face a global ocean, as the consequence of the meteorite impact that reduce planet's angular momentum to nearly 0. Such an impact, if you consider planetary physics would have created secondary ripples on the antipodes, in the day face. Such example are found on Mercury and Mimas (Saturn's satellite). You can expect to have a large landscape of the day face with large and deep canyons and cliffs, over a tumultuous ocean (don't forget the strong winds).

You might want also to look at the kind of volcanism the planet has: either with tectonic, such as Earth, or fixed crust. The presence of a closer moon would mean more active volcanism, but tectonic has the particularity to reset the surface from time to time, whereas fixed crust would mean very large volcanos on hot spots (think Mars' volcano who are 30 km high).

[Lord Torath]

You might want also to look at the kind of volcanism the planet has: either with tectonic, such as Earth, or fixed crust. The presence of a closer moon would mean more active volcanism, but tectonic has the particularity to reset the surface from time to time, whereas fixed crust would mean very large volcanos on hot spots (think Mars' volcano who are 30 km high).I presume you mean the moon would cause move volcanoes via tides acting on the planet? I did some math a few posts back showing that the tidal force exerted by the moon would be identical to that created by Luna here on Earth. The moon orbits much closer to Andorlaine than Luna does to Earth, but it has the same apparent diameter. Assuming the same density (AOTRS Commander hasn't commented on the density of the moon, that I can recall), the distance cubed term cancels out with the 1/diameter cubed for the moon's volume (and hence, mass) term resulting in the same tidal forces. It seems to me that a smaller moon will generally tend to be less dense than a larger one, since there is less gravity pulling everything to the center, which would tend to result in weaker tides, not stronger ones.

Those tidal forces will move much more slowly on Andorlaine, of course, since it is entirely dependent on the orbital speed of the moon, since Andorlaine's rotational speed is effectively zero (one rotation every 1300 years or so). So the tides last a day and a half instead of 6 hours. I will admit I don't know what effect that slower tide will have. On the one hand, it might have a stronger effect on slower-flowing material like magma, but on the other hand, the closer to the core of the planet, the smaller the tidal force from the moon.

[Aotrs Commander]

You seemed to have studied your case a lot lol ;)

I did spend several months hashing out as much as I could within the region of "statistically high unlikely, but not statistically impossible" as much as possible. Aside from the hand-wavy sun lifetime, the only other area I had to resort to "we don't know/something did it" was stellar wind, because I couldb't even find the calculations to estimate it. (That actually stalled me out for a good long while.)


I had assumed a nearly human life form for the exercice, so several of my comments might not apply for a "too-much" alien life form.

There will be creatures that are humanoid, certainly (as in bipedal stance, two arms two legs and a head), though beyond that, the point was to not have just have human-knobbly-forehead aliens. But at the same time split the difference of not being SO alien (like a whole party of ghost jellies or something) it becomes difficult to run a campaign with. As I said to some folk on the speculative evolution rediit where I alos posted this, there is a level of practicality required that you can get away without when writing something from a purely narrative or documentory format. The protagonists species have to be within spitting difference so the PLAYERS can have some understanding, so you can't got too far afield. (Particularly with regard to senses; how would you even describe to the players the world as perceived through something whose primary sense is electromagnetism or something.)

It's a hard needle to thread, else I'd have got further than I have.

(As it is, my great ambitions for the year - I wrote up a list of things and goals to try and make some progress towards - have met with brick wall after brick wall at some point (both work and play); forcing me to split my focus all over the place, which has been frustrating.)



One of the things to be taken into account is that the "nights" are actually unpredictable in length but also in magnitude. You can imagine to have "winters" that last a few months with still light as the sun is on low power but still visible, and winters that last years of blackout darkness. A daylight civilisation might endure several winters before "The One" that destroys everything and press the reset button. That would create even more myths about the "darkness that destroy".

Also, as light is nearly always present on the daylight half, sight would be the most useful sense for animals, and a drop in the ambiant light would have more effects on the life forms than on our world where a large fraction of the animals are nocturnal. Adaptation of night vision would be extremely rare, and reserved to subterranean species, invaders from the night side, or specific species from the penumbral circle.

Large oceans are indeed a stabilisation factor, whereas they are in the night or in day faces. It makes sense to have most of the night face a global ocean, as the consequence of the meteorite impact that reduce planet's angular momentum to nearly 0. Such an impact, if you consider planetary physics would have created secondary ripples on the antipodes, in the day face. Such example are found on Mercury and Mimas (Saturn's satellite). You can expect to have a large landscape of the day face with large and deep canyons and cliffs, over a tumultuous ocean (don't forget the strong winds).

That's all useful to know; a landscape of canyons and cliffs is also very useful to have, both on a cinematic and practical level. A big enough ravines could form something of a natural barrier to pre-industrial species, which would exascerabate the extinction pronlems.


You might want also to look at the kind of volcanism the planet has: either with tectonic, such as Earth, or fixed crust. The presence of a closer moon would mean more active volcanism, but tectonic has the particularity to reset the surface from time to time, whereas fixed crust would mean very large volcanos on hot spots (think Mars' volcano who are 30 km high).

Tectonic, I think, after doing some more research is going to be the approach (aggrevated by the relatively new presense of the moon, which will probably only be around for a few millon years, but that's more than enough to serve the purpose on the lifetime of cilivsations). So some tectonic shifting, which also will hopefully help the canyons and cliffs a bit. The idea of some places drifting very slowly Into The Darkness was other narrative hook I liked, and tectonics and some tide-unlocking (however relatively marginal) from the captured moon somewhat facilitate that.




I presume you mean the moon would cause move volcanoes via tides acting on the planet? I did some math a few posts back showing that the tidal force exerted by the moon would be identical to that created by Luna here on Earth. The moon orbits much closer to Andorlaine than Luna does to Earth, but it has the same apparent diameter. Assuming the same density (AOTRS Commander hasn't commented on the density of the moon, that I can recall), the distance cubed term cancels out with the 1/diameter cubed for the moon's volume (and hence, mass) term resulting in the same tidal forces. It seems to me that a smaller moon will generally tend to be less dense than a larger one, since there is less gravity pulling everything to the center, which would tend to result in weaker tides, not stronger ones.

Those tidal forces will move much more slowly on Andorlaine, of course, since it is entirely dependent on the orbital speed of the moon, since Andorlaine's rotational speed is effectively zero (one rotation every 1300 years or so). So the tides last a day and a half instead of 6 hours. I will admit I don't know what effect that slower tide will have. On the one hand, it might have a stronger effect on slower-flowing material like magma, but on the other hand, the closer to the core of the planet, the smaller the tidal force from the moon.

To my calculations, the tidal forces are roughly the same yes. (By my calculations, Andorlaine's moon imparts about 94% of the acceleration Luna imparts to Earth.)

It's actually slightly denser, since density is due to composition, not size (and it's a "recent" capture, ejected from something else). Especially being so relatively small, as well, composition is a higher factor.

For the record, 609km diameter, density of 3650kg/m³ (to Luna's 3350kg/m³), though due to the small size the surface gravity is very low (0.063g).

[Septimus]

...

My bad, I misread your message. Yes, tide intensity would be the same, but longer period would reduce the amount of energy transferred I think, so volcanism would be lower, with the caveat that not all the internal energy comes from tides, as radioactive decay is also a major provider of heat (in the case of Earth). So actually volcanism is moot point and I was wrong: it can be adjusted with lower/higher internal radioactivity to fit the setting wish list.

[Septimus]

I did spend several months hashing out as much as I could within the region of "statistically high unlikely, but not statistically impossible" as much as possible. Aside from the hand-wavy sun lifetime, the only other area I had to resort to "we don't know/something did it" was stellar wind, because I couldb't even find the calculations to estimate it. (That actually stalled me out for a good long while.)
Solar winds are difficult to model because we lack observations on something else than the Sun ^^
RCB giants are supposed to have significantly larger winds, something like a thousand to tens of thousands stronger winds. However, its impact decreases in square of the distance, hence also in thousand decrease factor. It might then be more or less the same than on Earth. It also depends on the strength of the magnetosphere of the planet, which in turn mostly depends on how much liquid the internal core is, and is related to volcanism. On the other hand, RCB have less hydrogen and more heavy elements in their photosphere, so solar eruptions (which are non isotropic) might have more impacts on the planet than sun's eruption. It may prevent development of advanced technology (on the day side), but should not have strong impact on life form (unless you want so), aside accelerating the evolution process.




There will be creatures that are humanoid, certainly (as in bipedal stance, two arms two legs and a head), though beyond that, the point was to not have just have human-knobbly-forehead aliens. But at the same time split the difference of not being SO alien (like a whole party of ghost jellies or something) it becomes difficult to run a campaign with. As I said to some folk on the speculative evolution rediit where I alos posted this, there is a level of practicality required that you can get away without when writing something from a purely narrative or documentory format. The protagonists species have to be within spitting difference so the PLAYERS can have some understanding, so you can't got too far afield. (Particularly with regard to senses; how would you even describe to the players the world as perceived through something whose primary sense is electromagnetism or something.)

It's a hard needle to thread, else I'd have got further than I have.I agree, alien is fine, but if you want players then it should not be too alien ;)


Tectonic, I think, after doing some more research is going to be the approach (aggrevated by the relatively new presense of the moon, which will probably only be around for a few millon years, but that's more than enough to serve the purpose on the lifetime of cilivsations). So some tectonic shifting, which also will hopefully help the canyons and cliffs a bit. The idea of some places drifting very slowly Into The Darkness was other narrative hook I liked, and tectonics and some tide-unlocking (however relatively marginal) from the captured moon somewhat facilitate that.
Yes, you're right: the recent adjunction of the moon would change the tide lock process, exchanging angular momentum. However, it might accelerate or decelerate rotation speed, and you might have a cataclysmic impact in the end, or the escape of the moon, depending the configuration.

[SouthpawSoldier]

Have any of you fine folks read Nightfall by Asimov? Details a culture in a similar situation to what OP describes. They aren't tidally locked, though; the planet orbits multiple stars, and they track time based on which suns are where in the sky.

Book details events when the culture experiences its first true nightime, with no suns in the sky.

[Palanan]

Originally Posted by Aotrs Commander
As it is, my great ambitions for the year - I wrote up a list of things and goals to try and make some progress towards - have met with brick wall after brick wall at some point (both work and play); forcing me to split my focus all over the place, which has been frustrating.

For what it’s worth, I know exactly how this feels.


Originally Posted by SouthpawSoldier
Have any of you fine folks read Nightfall by Asimov? Details a culture in a similar situation to what OP describes. They aren't tidally locked, though; the planet orbits multiple stars, and they track time based on which suns are where in the sky.

Book details events when the culture experiences its first true nightime, with no suns in the sky.

Yup, this parallel occurred to me as well, just didn’t have the bandwith to comment.

[Cinder39134]

There are prevailing winds from the night side to the day side, and the land is uneven. That suggests to me that you could have storm systems swept along with the prevailing winds. If their passing disturbed the region of the night side antipodal to the sun in the right way, a storm leaving might cause another to be made, and leave at a different direction, in some sort of periodic way. Basically, if the weather changes (and we know it does since you mentioned that it rains sometimes), maybe the conditions of the planet are right for massive storm systems to periodically sweep through at more or less consistent intervals, which would make a natural landmark for time to be set by? I don't know if that would be consistent with every part of the setup but it might make for something for natural cycles to be based off of (for example, storms throwing plant seeds everywhere for them to grow, so the plant would evolve to be ready to spread its seeds at that time) which would then solve most of the rest of the problem.

[Ashtagon]

You have no day/night cycle, and no seasons (or at least, no hot/cold cycle). It's cloudy enough that astronomy won't ever really be a thing. Wind patterns are consistent and not cyclical.

So, counter question: How prehistoric is this planet's moon? Because without tides, I'd question whether land life could even evolve. Fish, crustaceans, and octopi, yes, but not tetrapods. The kind of environment needed for some proto-fish to begin evolving legs simply doesn't exist on your planet.


Sleep cycles evolved as a natural consequence of day/night cycles. If they evolved without day and night, any life form complex enough to require something akin to sleep would do it in another manner.

So let's look at alternate sleep cycles found in nature.

Fish apparently don't "sleep" in the same way mammals do, but do rest in place. They tend to seek out relatively secure places (rock crevices, large schools, or just the sea floor), and remain aware of their surroundings. This can almost be likened to conventional D&D ideas about how elves "sleep".

Some species of ant apparently take one-minute power naps through the day and night, totally about 5-6 hours a day. They colony as a whole never sleeps though. Most insects tend to sleep for a few hours at a time, following a day/night (or night/day) cycle.

Crabs tend to be mostly nocturnal, sleeping through the day. It's not clearly understood what cycle deep sea crabs follow, as they never see daylight. Fiddler crabs, which tend to live in tidal shallows, are an exception. Their sleep patterns follow tides, rather than day/night cycles.

Octopi are known to both sleep and dream. (Due to the fact that we can't actually ask any of them, we only know about dreaming for sure with a very small number of animals.)

Frogs sleep. But not in the same way as mammals. Their sleep cycles vary by species, by generally depend on day/night cycles. They also incorporate aspects of fish-like 'sleep' and non-dreaming 'unconscious' sleep.

Finally, some animals hibernate/estviate in winter/summer. In a sufficiently extreme environment, a fantasy species might get all of its 'sleep' in this manner, being constantly awake and alert the rest of the time.

----

So, all life needs to "rest". Sleep as we understand it (and especially dreaming) seems to be a requirement only for life with complex brains. Past a certain level (amphibians?) Some of that sleep needs to be unconscious. Past a higher level than that (mammals and reptiles?), the sleep includes dreaming. The exact cycle varies, but almost always follows from an environmental trigger, whether that be light levels, tides, or winds that change in a regular cycle.

[D&D_Fan]

Okay, let's assume the planet has an Earth-like atmosphere that distributes temperature such that the front of the planet isn't as inhospitable and the back side of the planet isn't as inhospitable. Wind and air are essential, heating and cooling cycles, rain, even the dark side is livable, it could even be comfortable in the right planetary conditions.

If there's an orbiting moon, time is based off of that. If the constellations change, the time is based off of that. If the planet orbits the sun, there will be time based on that. If an alien civilization brings their own timepieces, then those can be used too.

If neither are true, then it's always possible that time can be based off of movement and travel. One day? You mean how long it takes to walk 20 miles? It's a silly measurement to us, but at least it's mostly practical.

Biological clocks still exist as well, as many people have said, animals mature at rates and times, so they know when to mate and migrate.

All I know is that it would be very different from earth.

[Ashtagon]

If neither are true, then it's always possible that time can be based off of movement and travel. One day? You mean how long it takes to walk 20 miles? It's a silly measurement to us, but at least it's mostly practical.


A mile is traditionally defined as eight times the distance a farmer can plough in one morning (ie eight furlongs). Which makes your 'day' definition somewhat circular.

[D&D_Fan]

A mile is traditionally defined as eight times the distance a farmer can plough in one morning (ie eight furlongs). Which makes your 'day' definition somewhat circular.

Just imagine it in reverse, if the day was defined by the distance plowed, not the distance plowed by the day.

[Ashtagon]

So... "A 'day' is the time it takes to plough the distance between A and B."

Ron is strong. Ron's day is shorter than Wayne the weak.

I suppose that works about as well as the traditional units of length based on the body, albeit with a different set of arguments developing.

I'm still curious how these guys are gonna evolve legs with no tides in prehistoric times.

[Aotrs Commander]

So... "A 'day' is the time it takes to plough the distance between A and B."

Ron is strong. Ron's day is shorter than Wayne the weak.

I suppose that works about as well as the traditional units of length based on the body, albeit with a different set of arguments developing.

I'm still curious how these guys are gonna evolve legs with no tides in prehistoric times.

I imagine the same way as the arthropods did, a long time before there was any life on land. I'm not terribly sure I buy the arguement that amphibans only moved onto land solely because of tides (as I have never heard that theory posited until now) when there are a lot of other plausible reasons - like exploiting a new environmental niche (and there are no tides in fresh water, for another point); but even if so, a completely different roll of the dice might mean that there are not vertebrate fish in the terrestrial sense (or if they are, they may not be what moved onto land) and the land dwellers came from a different "vertebrate" group which evolved from something that, I dunno, started in the trilobite mould/niche (or sea-scorpion or...)

[Ashtagon]

The process is something like this...

Fish live in coastal waters.

Some of those fish explore waters that happen to be tidal. Perhaps the tidal waters are where land-dwelling plant life (food!) happens to live, accessible to fish at high tide but generally inaccessible at low tide.

They get caught out by a low tide and stranded on tidal sands.

Some of these stranded fish suffocate and die. Others figure out that by flopping around on their fins and writhing in a particular way, they can make it back to water.

The fish that happen to be able to flop back to water have an advantage over the ones that can't, as they can continue feeding in the tidal waters for longer. This means they can go forth and multiply more easily.

Random evolution means some of these "flopper fish" develop stronger fins; others develop weaker fins. The weaker-finned ones give up on flopping onto the tidal sands (or die, like the regular fish that get caught). The stronger-finned flopper-fish thrive even more, as their stronger fins enable them to flop around on the tidal sands more effectively.

Over time, these stronger-finned flopper-fish develop their fins into something resembling actual legs.

Without a moon, you don't get tides, you don't get tidal waters, and you don't get fish trapped on tidal sands, so this entire sequence of events can't happen.

(Yes, I know there are solar tides too. But that relies on planetary rotation, and this planet is in an orbit and rotation that is functionally tide-locked as far as solar tides are concerned.)

Loosely related: https://www.youtube.com/watch?v=M6_7Q7uUhmU

[Lord Torath]

But there is a moon, even if it's only been around for a few million years.

AORTS Commander, is that a few million "Earth" years, or a few million "Andorlaine" years? Because a few million Andorlaine years is a few billion Earth years.

[Aotrs Commander]

The process is something like this...

Fish live in coastal waters.

Some of those fish explore waters that happen to be tidal. Perhaps the tidal waters are where land-dwelling plant life (food!) happens to live, accessible to fish at high tide but generally inaccessible at low tide.

They get caught out by a low tide and stranded on tidal sands.

Some of these stranded fish suffocate and die. Others figure out that by flopping around on their fins and writhing in a particular way, they can make it back to water.

The fish that happen to be able to flop back to water have an advantage over the ones that can't, as they can continue feeding in the tidal waters for longer. This means they can go forth and multiply more easily.

Random evolution means some of these "flopper fish" develop stronger fins; others develop weaker fins. The weaker-finned ones give up on flopping onto the tidal sands (or die, like the regular fish that get caught). The stronger-finned flopper-fish thrive even more, as their stronger fins enable them to flop around on the tidal sands more effectively.

Over time, these stronger-finned flopper-fish develop their fins into something resembling actual legs.

Without a moon, you don't get tides, you don't get tidal waters, and you don't get fish trapped on tidal sands, so this entire sequence of events can't happen.

Having googled around the subject, there does appear to be a suggestions that tetrapods may have formed in tidal areas (OR areas of shallow fresh water) but, like, otherwise, no, that's... Not remotely what those studies are suggesting. Far more credibly, it is suggested that forcing through shallow water plant growth (e.g. mangrove swamps) may have been a contributing factor.

(We don't know NEARLY enough about early tetrapod evolution to be able to say "if not for this one factor" - and that in general, there is very rarely any one single cause for stuff in natural history anyway.)

What this would only mostly suggest though, is that any "vertebrate" "fish" are less likely to have evolved in to "vertebrate" "amphibians" and that the role of larger land creatures may belong to a more diverse number of kingdoms that evolved from more arthropodic-like stock. So it's a point to consider, certainly, but its by no means a "legs can't happen without tides."

(But it's also worth remembering that, at the end of the day evolution is ultimately a bit of a gamle); adaptions have a CHANCE of happening - and the first mutant has to survive long enough to reproduce (and the mutation has to be one dominant enough to be passed on); the chances come up because there's so many rolls of the dice, but sometimes, not even rolling all the dice guarentees a result. Conversely, sometimes nature rolls a few natural 20s in a row. A freak storm tosses something thousands of miles from where it lives an it survives and florishes.




Loosely related: https://www.youtube.com/watch?v=M6_7Q7uUhmU

Mu understanding was already that tetrapods have basically because that's what it turned out early on (why, we simply don't yet know), as and the video says, once you're lost 'em, you don't get 'em back.

(Thus, for example, to skip to another world and another alien species, the elenthnars, which have four "spider-ish" like legs and an upright torso with arms with four fingers and two opposable thumbs (because they came from arborial, not cursorial stock) indicate that the kingdom to which the E'len'deth'nacri (to use the scientific name) come from would likewise have been one whose hexapods developed and retained a six-digit pattern.)



But there is a moon, even if it's only been around for a few million years.

AORTS Commander, is that a few million "Earth" years, or a few million "Andorlaine" years? Because a few million Andorlaine years is a few billion Earth years.

Earth-standard years. Given the high orbit speed, it won't be stable in the orbit for many millions of years.

[Palanan]

Originally Posted by Ashtagon
The process is something like this...

As someone who’s both published on vertebrate evolution and who knows a thing or two about coastal environments, the “process” is nothing like that. I’ve never heard this claim before, and without going through every line of this post, I’ll just say that none of it is supported by any actual science we have. A red flag for me is the casual mention that these supposed fish “figure out” how to move on their fins. No one versed in evolutionary biology would phrase a major transition like this.

A recent paper from Byrne et al. suggests that tidal variation may have been one of several factors influencing vertebrate colonization of land, but at best this is correlation, hardly causation. They rather grandly describe their approach as “a field holding great promise” which is “still very much in its infancy.” That’s a long way from demonstrating any actual evolutionary effect, much less proving that tides are the cause of vertebrate expansion into terrestrial environments.

It’s also worth noting that tidal variation is only one of a number of ways in which fish can be brought into the land/water interface. River deltas, land subsidence, wind-driven waves, and seiches can all serve to populate an intertidal region on different timescales. And there’s no reason to assume that a direct marine-to-land transition is necessary, or the only possible avenue, when marine-to-freshwater-to-land is just as likely if not more so. As just one possibility, if anadromous fish evolved early on, that behavior could put them in a similar situation to Bryne et al.’s putative tide pools, but in a purely freshwater environment, without the need for actual tides.

So there are plenty of ways that vertebrates, or vertebrate analogues, could evolve on Andorlaine without requiring Earth-equivalent tides.

[Lord Torath]

And Andorlaine does have Earth-like tides. I did the math a page or so ago, showing that the tides the moon exerts on Andorlaine are the same as Luna exerts on the Earth. They last six times as long on Andorlaine, and lack the component the Sun gives our tides (which I understand is about a 10th as strong as Luna's tidal effect), so Andorlaine still has a variable land/sea interface. Of course, it's only had that for a few million years, and will only keep it for a few million more, but it does have tides.

[Palanan]

Yes, I did see that Andorlaine currently has Earth-approximate tides, but I’m assuming that the ancestry of its vertebrate-equivalents reaches back hundreds of millions of years, long before its current moon arrived.

It’s also occurred to me that a regular seiche in a large lake or small ocean basin could mimic tides under certain circumstances, and might be frequent enough to serve for approximate timekeeping. How that interacts with the current tide regime is up to the OP.

[Ashtagon]

No one versed in evolutionary biology would phrase a major transition like this.

Let's just say that were I writing an academic article or a university paper where I would be expected to cite references and annotate everything, I would have phrased it differently.

This is an internet forum for gamers, not a symposium of professors. I write to my audience.

[Aotrs Commander]

For the record, while I am not an Actual Paleotologist as Palanan is (which is dead cool, by the way), but I a very keenly interested layperson; what started with dinosaurs quickly spiralled out at a young age with a book by Michel J Benton which covered in brief the whole history and that bored right into my hindbrain (along with my first exposure much later to Anomalocaris, which remains my favourite animal). (Hell, part OF doing an entirely alien world is to apply the theory. I never create an aliens without asking "how did they evolve?") So I would consider myself to know enough, as they say, to at least edge of out of the other side of Knowing Just Enough To Be Dangerous. I think Ashtagon, you were writing down more than necessary, especially when you were replying to me specifically, as it made you sound to me like you understood it far less than I do. (I mean, I went and learned to do astrophysics maths for this, I would hope from context that would have at least suggested I can cope with at least the highest grade of popular science, if not bottom-end technical.)

[Palanan]

Originally Posted by Aotrs Commander
For the record, while I am not an Actual Paleotologist as Palanan….

Not a paleontologist sensu stricto, but there’s some overlap.


Originally Posted by Aotrs Commander
…Anomalocaris, which remains my favourite animal….

And fine taste you have indeed.


Originally Posted by Aotrs Commander
…I never create an aliens without asking "how did they evolve?"

Speaking of which, do you have a definitive list of the sapients which evolved on Andorlaine? I have a vague impression from this and previous threads, but I can’t recall if you’ve ever presented the full spectrum of species available as PCs for this world.

[Aotrs Commander]

Speaking of which, do you have a definitive list of the sapients which evolved on Andorlaine? I have a vague impression from this and previous threads, but I can’t recall if you’ve ever presented the full spectrum of species available as PCs for this world.

None, currently. There is the implication from the ghost-ship-city of the "ghost jellies" the Aotrs party briefly explored that there are probably humanoids(or something close) of roughly humanoid proportions, but basically thus far the only "on-screen" and coherent creatures are the "ghost-jellies" (seen as corpes as then as, like, ghosts...) and the rib-cage of a "demon brain." (Oh, as some vaguely shark-like EM insubstantial creatures from the Dark Side.) But that's it so far. The paleolithic tribe under consideration would be ostensibly the first.

Though if it wasn't already clear, the assumption will be multiple sophont species (of disprate morphologies) like a more traditional fantasy planet, rather than a monospecies-type set-up.

(With 2023 being what it is, work aside, my time is being completed with by three seperate projects - this, setting up my even-longer-desried non-egyptian mega-campaign (and trying to fit Desert of Desolation onto Golarion, which is harder than I expected geopgraphically...) and my major job convering over all my BattleTech record sheets (for about 400 mech models, of which there are an average of five variants per model...) from one outdated piece of software to a new one. So it's all slow going.)

[DavidSh]

A mile is traditionally defined as eight times the distance a farmer can plough in one morning (ie eight furlongs). Which makes your 'day' definition somewhat circular.
I had thought it went back to Roman times, as a thousand paces (mille passus). Or is that just a mad coincidence. I know my walking cadence at about 100 steps (50 paces) a minute gives me about three miles an hour.

[Ashtagon]

I had thought it went back to Roman times, as a thousand paces (mille passus). Or is that just a mad coincidence. I know my walking cadence at about 100 steps (50 paces) a minute gives me about three miles an hour.

It's complicated. There are many units that have been called a mile, and they vary quite considerably in length. The longest "mile", the Norwegian mil, was more than twice twice the modern international mile (most Scandinavian countries these days use "mil" to mean exactly 10 km). The Roman mile (at about 1480 m) is in fact the shortest unit traditionally referred to as a "mile" (or an etymological descendant of that "mille passus").

The English furlong ("furrow-length") was defined as I noted. That it approximates the Greek/Roman stadion/stadia is coincidence rather than intent.

The English word "mile" does indeed ultimately come from Latin. But the Roman definition of 1000 paces isn't exactly convenient. In a pre-literate age, counting that high requires a lot of concentration on the numbers, as well as concentration on maintaining a steady pace (ie marching). This was outside most peoples normal daily lives. What was within most peoples normal daily lives was farming. So it was natural to find a number of furrow-lengths that would approximate the older unit, in order to continue to make sense of the existing milestone markers that would have remained in place along the old Roman roads long after the empire itself had fallen.

In other words, they took the existing word, and redefined it in terms of units that they were using on a regular basis. Kind of like how in modern times we took the existing mile, and redefined it as an exact number of metres, replacing the traditional definitions then in use.