So who needs planets? Space habitats are more practical and have a clear title; whoever puts up the money to build it owns it. According to the Outer Space Treaty, although nations can't claim ownership of asteroids or moons, anyone who mines one can own whatever materials they remove (A wacky law birthed from Cold War politics) and can build what they want from it. Why bog down in a gravity well when 1-g is only a spin away?

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort