Terraforming’s a bit of a thorny debate these days. Even leaving aside the question of whether or not we should be doing it in the first place — I once gave a talk where I referred to people who thought we should preserve the Martian surface as a sort of natural park as “crazy lunatics1”, only to have one of the other speakers come up to me afterwards and tell me he was one of them2 – there are many technological hurdles to be overcome, ranging all the way from raising/lowering the temperature of an entire planet to a liveable standard to generating a breathable atmosphere. While some of these hurdles are truly significant and will require decades – or even centuries – of technological advance before we can terraform a planet in any meaningful way, there’s also a lot of wilful obfuscation going on about just what is and isn’t possible in the first place. For example, some people will tell you that there’s no point in colonising and terraforming Mars because it’s too small to effectively retain an atmosphere. You should not trust these people, because they are lying – or at least, they are being very economical with the truth.