Venus Spins Backwards Slower Than It Orbits

Venus rotates so slowly that a single day on the planet lasts 243 Earth days. But here's what makes it truly strange: Venus takes only 225 Earth days to complete one full orbit around the sun. This means a Venusian day is actually longer than a Venusian year. Even more peculiar, Venus rotates backwards compared to most planets in our solar system, a phenomenon called retrograde rotation. Scientists believe a massive collision early in Venus's history knocked the planet sideways, reversing its spin. The collision was powerful enough to slow the rotation dramatically, but not powerful enough to stop it entirely. The slow rotation also means Venus experiences extreme temperature swings. The side facing the sun reaches 900 degrees Fahrenheit, hot enough to melt lead. The dark side cools somewhat, but the planet's thick atmosphere of carbon dioxide circulates heat so efficiently that even the night side stays brutally hot. If you stood on Venus and watched the sun, it would move backwards across the sky, rising in the west and setting in the east, at a pace so gradual you'd never notice the motion without instruments.