|Posted: 2012-April-10 at 11:31pm | IP Logged
I like it. Double inhabitable planets aren't impossible, so I can see a civilization no higher than ours colonizing the neighbor with chemical rockets. We probably would have, even if the neighbor had been Mars, instead of a thoroughly dead Moon.
As they would be tidally locked to each other, one can imagine a civilization beginning on the "back side" of one world, with no idea the other was there. On our world, park it over the eastern Pacific, about 100 degrees west, and Europeans would never suspect it. Then when they start exploring the Atlantic and Americas, there's a real "New World" just hanging there. Wonder what that would have done to science and religion?
If you're trying for scientific accuracy, the "moon" probably shouldn't be darker than the sky. As a test of an idea that doesn't matter.