Originally Posted by Mechalich
Well, it's huge and not huge at the same time. Austria is geographically tiny. Planets are big. 10 million people spread evenly across a planet would be super isolated. The Earth has ~150 million square kilometers of land area. Even if people utilize only 10% of the landmass, so 15 million sq km, 10 million people would be a population density of 0.66 per sq km. That's less than half the population density of Mongolia, which at 2.07 people/sq km is the least densely populated nation of any consequence on the planet. Mongolia is also an interesting point of comparison, because half of Mongolia's population lives in the capital city of Ulaanbaatar. Many colonies may be organized in similar fashion - a single large metro area with roughly half the population surrounded by cultivation/extraction zones containing the other half. However, I doubt they would be anything like that level of spread out. Instead, you probably have one major city centered around the primary spaceport and then high concentrations of people in the best extraction sites on the planet nearby. The average colony probably has a presence on well below 1% of the average planetary landmass. Austria, for example, occupies 0.55% of the Earth's land area.