Wednesday, December 02, 2009
Space.com has a good article on Super Earths today. Super Earths are a class of planet that have only recently been discovered, and whether they are suitable places for life or not is still a matter of debate. Due to plate tectonics some think for example that only planets with a mass anywhere from 0.5 to 2.5 times Earth should be able to support life, but then again Venus is a good example of a planet just about our size with almost no plate tectonics at all, so with that type of variation it's still hard to tell just what type of planet makes the best candidate for supporting life.
And by the way, theoretically there should be no reason why one of these planets not even orbiting a star (a so-called rogue planet) shouldn't be able to have life either, since a planet without a star would have an easy time retaining a thick atmosphere and plate tectonics would keep the planet warm for long enough for life to develop. In fact, without any nearby asteroids and comets after being thrown out of its solar system there would be no danger to life from these impacts either.
But then again, this is all just speculation and we still really have no idea what passes for normal even in our tiny corner of the universe. Discover another few thousand planets and we may be able to begin making some tenuous conclusions.