Where are all them habitable planets that we gonna move to when Earth becomes too hot ‘n’ nasty for us? (By “habitable”, astrobiobods mean host to liquid water.)
Turns out that a coupla good candidates are orbiting Gliese 581, a red dwarf star about 20 light years from here in the constellation of Libra (Gliese 581 is our 87th closest neighbor).
Now Franck “Ex” Selsis and pals from the Centre de Recherche Astrophysique de Lyon in France have been a-dreamin and a-wondrin what conditions are like on these planets, called GL581c and Gl 581d, which are just a little larger than Earth.
After mucho guessin’ calculatin’, they say 581c receives 30 per cent more energy than Venus and so is unlikely to have liquid water. 581d could be a better bet with conditons there close to those on early Mars, which is thought to have liquid water. Ex Selsis says that with the right kinda greenhouse gases, liquid water may be a distinct possibility on 581d. But how such a “super-greenhouse” atmosphere could be created and remain stable isn’t yet known (although it looks like we’re about to find out here on Earth).
So don’t getcha hopes up but do tell them astrobods to keep searchin’.
Ref: arxiv.org/abs/0710.5294: Habitable Planets Around the Star Gl 581?