October 2, 2010: See GURPS Space, Pages 125 And 127

Look in the direction of the constellation Libra. Go out about 20 light years . . . see that red dwarf? No, a little to the right -- that one! That's Gliese 581. Kinda ordinary, isn't it? But if you look at the habitable zone (that range of orbits around a star that would allow a planet to have liquid water on its surface), you'll find a big chunk of rock, unimaginatively named "Gliese 581g."

As suggested by GURPS Space on page 127, this planet is tide-locked, which means one side is always facing the sun, and the other is always facing away. There is a narrow band of twilight that would theoretically be habitable by humans. People from Canada, for instance (Hi there, Ross and Sean!), wouldn't find the -24 to 10 degrees too harsh.

Of course, unlike the predictions of numerous science fiction authors, we've found a potentially habitable extrasolar planet long before we have the capacity to visit. Personally, I'd hoped we'd be blind-jumping in and scanning the system with the ship's sensors to get this much info on Gliese 581. But I don't have my flying car either . . .

-- Paul Chapman