What do you think of this fact?
Imagine it’s your birthday, and the Sun hasn’t even finished one trip across the sky since your last one. On Venus, that would be totally normal. There, one spin on its axis takes longer than a full orbit around the Sun.
The slowest spin in the solar system
Earth spins once roughly every 24 hours. Venus needs about 243 Earth days. Its trip around the Sun, a Venus year, takes only about 225 Earth days.
Measured against the stars, a day on Venus is longer than a year on Venus. No other planet in our solar system spins this slowly.
And it goes backward
Almost all planets spin in the same direction they orbit the Sun. Not Venus. It rotates backward. The result: on Venus, the Sun rises in the west and sets in the east.
That backward spin has a strange side effect. Because rotation and orbit work against each other, the Sun returns to the same spot in the sky sooner than you’d expect. From one sunrise to the next takes about 117 Earth days. So a “solar day” is shorter than one full spin. Sounds like a paradox, but it’s just geometry.
Nobody knows exactly why
How Venus ended up with its slow, backward spin still isn’t fully settled. Ideas include massive impacts in the early solar system or the effects of its super thick atmosphere.
A day on Venus wouldn’t be pleasant, by the way. The atmosphere is mostly carbon dioxide, topped with clouds of sulfuric acid. The greenhouse effect heats the ground to more than 860 degrees Fahrenheit, or over 460 degrees Celsius. That makes Venus hotter than Mercury, even though Mercury is closer to the Sun.
After the Moon, Venus is the brightest natural object in the night sky, which is why it’s often called the “evening star” or “morning star.”
A year that’s over faster than a day: on Venus, the weekend would feel endless.