I need some setting help

[Jack_of_Spades]

My next campaign setting will take place in the ruins of the United States, about 6000 years after the discovery of magic. The previous 2000 were full of war because the instability of magic did something to the sun and it started sending out waves of radiation and microwaves and other deadly stuff and each nation thought the others were responsible and went to war. Eventually the original cause for war was forgotten and people just fought because they'd always been fighting.

Anyway, this leads to my question. The sun is for an unknown reason, a black hole. To prevent all life on earth from freezing to death, wizards lit the moon on fire. It works as the sun basically, but now I've complicated things. I'm not sure how long a "day" would be because I'm able to see the moon at day and night. I'm also not sure what sort of calender might be in use. There's no phases to keep track of the moon with and I'm fairly sure the weather and stuff would be too screwed up to use our regular calender.

I've really complicated things here, but my PCs all really like the idea of the black hole sun and burning moon along with the post apocalyptic stuff. I'd like to keep those elements, but I'm not sure how to keep track of in-game time.

[hamishspence]

29 days = a lunar orbit, roughly. so it would be a bit long compared to the 24 hours of a typical day. Unless it was moved much closer.

[Jack_of_Spades]

But we also spin. That's why we can see it every night...and sometimes day.

At least, I think that's how it works...

[Fireballing_Fun]

Black hole sun wont you come, and wash away all life, black hole sun, won't you come, won't you come, won't you come...

[hamishspence]

good point, forgot that- would only apply if rotation of planet had ceased for some reason.

In which case, moons orbit would not make huge difference, though it might create a new seasonal cycle, since its not exactly circular- slight ellipse.

[Xanedan]

It would vary in illumination (and heat!) during the course of each individual month as the geometric position to your current sky differs as the earth rotates (full moon = brightest portion and likely longest duration of the day) which nullifies any simplistic "this many days a week" type calendar as days (in the sense of daylight) are likely to drastically vary in length constantly. It's not impossible to imagine a calendar but it will be complex.

More troubling is the idea of a solar system without a sun. I believe the notion is blackholes can actually have gravitational pull (I think I read something of the sort) but I can't imagine the earth's orbit around this blackhole to be equal to the earth's orbit around the sun. The pull would be different, changing the rotation and likely causing all sorts of nasty interplanatary collisions and such.

Of course the obvious way around both of these problems is "A wizard did it". Hell, they set the moon on fire, have them make it rotate on a daily basis (somehow).

This is fun to think about, though. I might try to wrap my head around it in further depth when I'm at home.

[Fireballing_Fun]

Yes black holes do have gravitational pull, the nature of the moons orbit around the earth would be drastically altered as both moon and earth were slowly pulled into it.

[hamishspence]

Only if its gravity was significantly higher. If the sun was compressed enough, it would be a black hole. Much smaller than a standard one, though not small enough to be in danger of losing mass rapidly.

black holes don't suck things in any more than stars do- if you're orbiting at the right speed.

[Xanedan]

I mispoke, or more accurately completely failed to communicate what was going on in my head. It's a character flaw.

I meant to say that objects have been observed rotating around a black hole, can't remember where I read that but I'd say either Time or National Geographic, being the only two publications I've taken to reading lately.

Although I would imagine that's more of a "slowly rotating in towards oblivion" as opposed to "swiftly rotating in towards oblivion". Although time/space in relation to far off galaxies doesn't really equate so well to the milky way (which is relatively small) meaning "slowly" might just be a matter of days/hours/minutes until the earth and everything on it is sucked into the abyss.

Anyway, yes. I still propose that a wizard simply alters physics towards a better outcome. One that requires less thinking for common folk like you or me.

[Xanedan]

Only if its gravity was significantly higher. If the sun was compressed enough, it would be a black hole. Much smaller than a standard one, though not small enough to be in danger of losing mass rapidly.

black holes don't suck things in any more than stars do- if you're orbiting at the right speed.


Still, this would require the blackhole to take up less space than the sun, correct?

That's hardly epic. I envision staring off into the sky only to see a giant, gaping maw of darkness looking back at me. :-/

[hamishspence]

yes- but thats not normal for a black hole- its gigantic. Assuming same orbital distance.

5km diameter black hole would be 4 or 5 solar masses- something like that.

[The Rose Dragon]

Does something about the black holes make them inherent suckers more than any other mass?

Now, I'm no astrophysicist, but if something has the same amount of mass, it shouldn't matter whether it's a black hole or a sun - you get to keep your orbit as long as the center of mass doesn't change.

Fun fact, of course: the sun is constantly losing mass to generate the energy we live off of. When a tritium and a hydrogen fuse together, they form a helium, which has a lesser amount of mass than the sum of a tritium and a hydrogen.

So, over a very long time, the Earth may lose its orbit, but it should be away from the sun, not towards it.

((Still not an astrophysicist.))

[Oracle_Hunter]

Anyhoo, it looks like Black Holes should operate gravitationally just like their former star as long as you stay outside the Event Horizon (http://en.wikipedia.org/wiki/Event_horizon).

Oh, and you probably wouldn't notice the Sun-as-Black-Hole in the night's sky, unless it is eclipsed.

For more on Black Holes, please consult The Other Wiki. (http://en.wikipedia.org/wiki/Black_hole) :smallsmile:

[Fireballing_Fun]

Still, this would require the blackhole to take up less space than the sun, correct?

That's hardly epic. I envision staring off into the sky only to see a giant, gaping maw of darkness looking back at me. :-/

That would be awesome, maybe say that the black hole sun was sucking earth in, until eventually a Wizard(s) arrested, but did not reverse the process.

Bit too high magic for me mind.

[hamishspence]

Yes- I did my degree in astrophysics and can confirm this- unless you are really close, or your speed is utterly wrong for orbit, they do not suck things in.

Also- with Sun moving outward- its very slow, but Sun loses mass at a much faster rate in Red Giant phase- my end of degree project compared the rate at which the planet moves outward, with the expected density of the envelope and expected slow-down, and concluded even if gas envelope engulfs planet, it will STILL keep moving outward.

[Oracle_Hunter]

I mean, yeah, you should go with Magic Black Hole instead of Real Black Hole. Make it the mouth of an Elder God that drives people crazy if they stare at it in the night's sky. Give some Eldrich Illumination (tm) - a ring of witchfire around a disk of nothingness - and you're done.

[hamishspence]

Elder Evils has a couple of Giant Space Monsters- Ragnorra, and Atropus, though Ragnorra is closer to the classic "alien invador"

[Xanedan]

I mean, yeah, you should go with Magic Black Hole instead of Real Black Hole. Make it the mouth of an Elder God that drives people crazy if they stare at it in the night's sky. Give some Eldrich Illumination (tm) - a ring of witchfire around a disk of nothingness - and you're done.

I'm sold on this plan.

Anywho, I think what others have said is grounds enough to flesh out your setting a little more. My advice (also not an astrophycisist, hell I didn't even take physics) is to let the story and the mood take prevalence. Paint the picture in your head of what someone living in this world sees on a daily basis, and fill in the science only when the story calls for it.

[Oracle_Hunter]

Oh hey, OP - if the wizards can permanently set the moon on fire, why don't they also adjust it so that it provides night/day just like the old sun did?

And don't give me any guff about Science - the friggin' moon is on fire. :smalltongue:

[The Rose Dragon]

And don't give me any guff about Science - the friggin' moon is on fire. :smalltongue:

Wait... where does the moon get any oxidizers from?

[Paramour Pink]

It's crazy that despite playing Skies of Arcadia, all I can add to this topic is, "Moons, give me strength!" All those hours playing an air pirate on a world with like five different moons for nothing!! :smallmad:

Thought maybe you should consider another factor...how badly are plant and animal life affected? Is there any impact on the tide? Lighting the whole moon on fire has to mess around with those things a little, though I'm assuming that's why things are apcolyptic with you.

[Xanedan]

If anything this thread has convinced me that lighting the moon on fire is a lot more complicated than it would initially seem.

I will take this lesson to heart.

[hamishspence]

Magic: but, if one wants a reason, it could be- permanent spell converting matter to energy directly. The energy provides light (and heat) the huge bulk of moon provides fuel, the spell (probably epic) ensures that only are very thin layer over moons surface is being converted at any one time, a la matter-antimatter reaction, but without antimatter, just matter breakdown.

Yes, I probably killed half a dozen catgirls by airing the theory, but it dodges the oxidiser issue by it not being "real fire."

[Graymayre]

I'm surprised no one has said this. The moon is slowly leaving Earth's gravitational pull. In several thousand years, it may be too far away for use, or even gone.

But that, of course, takes back seat to flavor. The main point is that it won't match the lunar revolutions of today.

[hamishspence]

Several thousand years? I thought it would take a whole lot longer than that, given the timescale since the moon was formed (4 billion odd years)

[Oracle_Hunter]

Teh Intertubes (http://curious.astro.cornell.edu/question.php?number=124) says that the moon moves away at 0.038m per year. In 6000 years, the moon will have moved 228m away from Earth.

Not exactly spiraling to oblivion, eh :smalltongue:

Also: Magic stabilized its orbit.

[hamishspence]

in 6 billion years, it will be something like twice as far as it is now, extrapolating.

So, not within the lifespan of the star in the system.

[Tiki Snakes]

Why even bother with a predictable orbit? The Sun is a gaping wound in space and time, (possibly with teeth the size of a thousand worlds!). The Moon is ON FIRE.

Have an unpredictable orbit. Roll every 3-6 hours to see if the moon is going down/rising. You could have a sunset every 6 hours for a week and it not be night-time once, or you could see no sun on your side of the planet for a month. Or you could have a cycle of night and day that almost made sense for several years.


Imagine the sheer licence for pathetic fallacy that grants you, as a story-teller?

[Valentyne]

Its true, the blackhole would not be visible. However, the accretion disk may be visible....perhaps formed out of the outer layer of the sun as the center collapsed into the blackhole....or someother such phenomena. And it would create quite the sight...

[bosssmiley]

Anyway, this leads to my question. The sun is for an unknown reason, a black hole. To prevent all life on earth from freezing to death, wizards lit the moon on fire.

I have a new household god!

That is...

It's...

Oh wow!

:smallbiggrin::smallbiggrin::smallbiggrin:

Can't help. Mind too blown. All I can offer is changing Earth to an 80+ degree axial tilt to give really severe seasons as it slowly rotates during its annual(?) orbits of the singularity primary. Quite how the lunar light source will look on a planet like this re-blows my mind for me. Effectivly you have a lunar orbit switching from planetary polar to equatorial over the course of an equinox-solstice period...I think.

I'm off for a lie down.

[Curmudgeon]

Assuming the whole of the Moon is illuminated (or at least the face constantly facing Earth is) to replicate the Sun's radiation, you'll basically have a much shorter season. Though the Moon will provide the same amount of light and heat daily, since its orbit is pretty much in the Solar ecliptic the Earth's constant tilt relative to that plane will let the planet experience the full summer-winter progression every 29.5 days (a synodic month), or about 12.4 times as fast as now. That's going to make for severe weather, but milder seasonal temperature swings since the planet won't have as much time to heat up or cool off.

[Jack_of_Spades]

Wow, lots of great ideas here! I really like the maw of madness thing! I also like the random orbit idea because it adds an air of danger. Anything unpredictable can seem dangerous!

Here's some other campaign stuff if anyone wants more besides the black hole sun and fire moon.

Gods: There's alot of them, many of which were also worshipped in The Old Age.

Jesus: He lives at the north pole and comes down once a year to hide colorful eggs for the good boys and girls. He wants his clerics to reestablish the world by showing others how to be good. His holy symbol is a cross. He's the Easter Bunny, Santa, and Jesus all in one.

Aol: Aol is the god of Justice and Law. Her clerics are expected to bring their law with them and enforce it. Order is what is needed to fix the world not foolish notions of Good or Evil. Her holy symbol is a small disc, one side is shiny and reflective and the other bears her name. Her clerics are basically like the Judges from Judge Dredd.

Bank: Bank is the god of tyranny and greed. His clerics are the rightful inheritors of the world. They set up and control economies where they preach and often charge them heavily. He's basically Bane, but he has a K instead of an E at the end. His holy symbol is an $. He is also the son of Usa.

Usa: Usa is the god of freedom and civilization. He is basically Erathis with a different name. His holy symbol is Eagle clutching missiles in one talon and wheat in the other.

Nasa: Nasa is the daughter of Usa, she is a god of Sacrifice and Fire. She sacrificed herself to ignite and sustain the moon when she saw that the people would die. She gives her clerics no orders, she is dead, but they have formed their own dogma in her memory. If they can sacrifice themselves for the good of others it is a great idea to do so. Bring the light of good into the darkness. Her holy symbol is the sun.

Sun: The sun is a dark brooding god. He devoured the spark that once sustained the world, but was thwarted by Nasa. His orders are few, but evil. His clerics cause destruction to try and bring their lords dream to fruition. Many madnesses are blamed on his shadowy touch. His holy symbol is a black sphere, the size of a fist.

I'm still trying to think of other gods too include.

[hamishspence]

Problem is, accretion discs require lots of gas to, well, accrete. In some cases, this can be an adjacent star, close enough (within Roche lobe) for gas to be dragged off.

shortest seasons I've ever seen in fiction were on a planet in the Deathstalker cycle by Simon R. Green- 8 day cycle from spring to spring. Caused by sabotaged "weather satellites"

[bosssmiley]

I'm still trying to think of other gods too include.

Oirop: The many-headed dragon god who comes from the sea. Crowned in stars, Oirop speaks in a thousand discordant voices and is motivated by never-ending hunger and avarice. He/she/it plots endlessly to see Usa and the other gods subjugated. His cultists are a combination of scheming manipulators and wild-eyed zealots.

Borealis, Light of the North: You might want to make some of the other gods a little more portmanteau in nature. Change the mash-up Jesus so that he's less obviously...well, Jesus. Make him a man in a long red coat who hides rabbit ears under his flat brown hat. Stories say he comes from the north riding a tame bear and bearing gifts when the year is at its coldest and darkest. His symbol? Well, it looks kind of like a crozier...or maybe a hockey stick. Oh, and the stories say that he was found in a basket by shepherds...
There. You still a figure of hope, but less obviously informed by current Christian iconography, and more by folk culture.

Usa: you could change Usa to something like a white-bearded father god in a tall hat and a starry robe. Old books have pictures of wise Usa disciplining or helping foreign gods. Maybe mention something about his beautiful torch-bearing bride Columbia...

One interesting godling I read about over at Banter Latte was Essad (http://banter-latte.annotations.com/2007/07/23/mythology-of-the-modern-world-whats-the-real-deal-with-gasoline-prices/), the mighty, yet sickly, spirit of oil. He has something of the djinn and something of Caliban about him...

[hamishspence]

you know, there are claims that Certain Figures from iconography are already like that- a mismash of older legends.

So, I like the idea.