Venus's green house gases trap in the heat from the sun, where as Mercury has none and also is extremely cold when not facing the sun, venus stays hot because the Suns heat can't escape due to green house gases. Dude are you a troll or not? Could you just tell me because I feel like everyone knew this :/ Edit: and really should have said the greenhouse effect, essentially because venus is so polluted with green house gases even though it's further, it's a hell of a lot hotter. But also this is science fiction so real world rules don't apply...