Rationalizing a Firefly - Serenity type setting

[mindstalk]

Originally Posted by Fred Brackin

You can then play with double planets as natural occurrences but you still only have one real habitable zone per star.

Terraformable moons of gas giants remain hypothetical objects. Jupiter doesn't have any and only lack of knowledge about Titan's innards keeps it as a maybe. Go out to Neptune to find the next big moons and you're looking at places where nitrogen is a granite hard solid. Heat one of those to human-friendly temps and who knows if things would work out all right.

Terraformable anything remains a hypothetical object. Many gas giants are much closer to their stars than ours, though, if worrying about habitable zones. If using fusion-powered artificial suns in orbit, even that's not really a concern.