I think I might have a possible explanation for the peculiar, west-to-east rotation of Venus, where a day is longer than a year. Venus "wants" to have one side always facing the sun, so that one rotation would equal one revolution (like the Moon). However, once Venus achieved this state, every time it was in opposition to Earth (at which point it is only .3 AU's away), it would also "want" to have one side always pointing at Earth. This represents a glancing, gravitational, inelastic collision that would induce a tiny westward "kick" to Venus everytime it speeds past the Earth that might be enough to cause the slow retrograde rotation. It's sort of like when a cue ball strikes a glancing blow on the left side of another pool ball, a left-ward spin is induced.:tongue: I've completely forgot how to do calculus, so I don't have much of an idea as to how to quantitatively attack this problem to see if I am crazy or not. :uhh: Any ideas?