Why Venus Spins BACKWARDS — and No One Is Sure Why

On Venus, the Sun rises in the west — and sets in the east.

Almost everything in our solar system spins the same direction, spun up by the swirling disk of gas that formed the Sun over four billion years ago.

Venus rotates backwards — so slowly that it takes 243 Earth days to spin once. Why it flipped is still debated: a colossal ancient impact may have knocked it over, or the Sun's gravity acting on its thick atmosphere gradually dragged its spin into reverse over billions of years. Whatever happened, Venus now turns clockwise, against the grain of the solar system.

And it isn't entirely alone — Uranus is tipped almost completely onto its side. But Venus is the one world that simply runs in reverse, against the entire system, and we still can't say for certain why.

Follow The Cosmic Vault — the universe is stranger than you think.