A Day on Venus Lasts Longer Than a Full Venusian Year — 243 Earth Days vs. 225

Venus is the strangest of all the rocky planets. Roughly the same size as Earth, it has surface temperatures of 465°C, an atmosphere 90 times denser than ours, and clouds made of sulfuric acid. But its weirdest feature might be its calendar.

Venus rotates so slowly that a single rotation — one Venusian day — takes 243 Earth days. But its orbit around the Sun takes only 225 Earth days. Result: one day on Venus is longer than one year.

And It Spins Backward

Venus rotates in the opposite direction from every other planet (except Uranus, which spins on its side). On Venus, the Sun rises in the west and sets in the east. A single Venusian solar day — the time between two sunrises — is about 117 Earth days, due to the combined effect of slow backward rotation and forward orbit.

Why Does Venus Spin So Strangely?

• One theory: a giant ancient impact flipped its rotation
• Another: tidal interactions with the Sun and dense atmosphere gradually slowed and reversed it
• The atmosphere itself rotates 60 times faster than the surface — a phenomenon called "super-rotation"

Other Venusian Oddities

Venus has no moon, no magnetic field, and the surface pressure is equivalent to being 900 meters underwater on Earth. Soviet probes that landed there in the 1970s lasted only a few hours before melting and being crushed.