Venus Spins Backwards Slower Than It Orbits

Venus does something genuinely strange among planets in our solar system. It rotates on its axis so slowly that a single day on Venus, measured from sunrise to sunrise, actually takes longer than a Venusian year. One rotation takes about 243 Earth days, while Venus completes its entire orbit around the sun in just 225 Earth days. More peculiar still, Venus rotates backwards compared to most planets. If you stood on Venus and watched the sun, it would rise in the west and set in the east, the opposite of Earth. Scientists aren't certain why this retrograde rotation happens. The leading theory involves a massive collision early in Venus's history that flipped its rotation, though some models suggest atmospheric interactions with solar radiation may have gradually reversed it over time. This backward spin also means Venus's upper atmosphere moves faster than the planet rotates. Winds in the Venusian clouds circle the entire planet in just four Earth days, creating hurricane-force speeds of 360 kilometers per hour. The planet's thick carbon dioxide atmosphere, combined with this odd rotation, traps heat so effectively that Venus is hotter than Mercury despite being farther from the sun.