On Venus, a day lasts longer than a year.
Venus takes 243 Earth days to spin once on its axis, but only 225 days to orbit the Sun. It also spins backwards compared with most planets, so if you could see through its crushing clouds, the Sun would rise in the west.
Venus is Earth's nearest planetary neighbour and almost its twin in size, but it could hardly be less welcoming. Its surface is hot enough to melt lead, around 465°C, and its atmosphere of carbon dioxide presses down with about 90 times the pressure at Earth's sea level. A runaway greenhouse effect makes it hotter than Mercury, even though Mercury is closer to the Sun.
Its rotation is the strangest thing about it. Measured against the distant stars, Venus turns once every 243 Earth days, while it completes an orbit of the Sun in about 225. So its sidereal day is longer than its year. And it turns in the opposite direction to Earth and most other planets, a motion astronomers call retrograde rotation.
Combine the slow backward spin with its orbit and you get a solar day, from one sunrise to the next, of about 117 Earth days. Nobody knows for certain why Venus spins this way. Leading ideas include a giant collision early in its history, or the slow drag of the Sun's gravity on its thick atmosphere, which may have gradually braked and even reversed its spin.
Meanwhile the atmosphere itself races around the planet far faster than the ground beneath it. The upper cloud layers circle Venus in about four Earth days, a phenomenon called super-rotation. The planet barely turns, but its sky is in a permanent gale.
Source: Wikipedia — Venus · Text summarised from Wikipedia (CC BY-SA 4.0)
