How long is a day on each planet?
A day lasts 24 hours 39 minutes on Mars, just 9 hours 56 minutes on Jupiter (the shortest), 10 hours 34 minutes on Saturn and a staggering 243 Earth days on Venus, which spins backwards. Here are the day and year lengths of every planet.
Key facts
| Shortest day | Jupiter, 9 h 56 min |
|---|---|
| Longest spin | Venus, 243 Earth days |
| Longest sunrise-to-sunrise | Mercury, 176 Earth days |
| Most Earth-like day | Mars, 24 h 39 min |
| Shortest year | Mercury, 88 days |
| Longest year (planets) | Neptune, 164.8 Earth years |
| Planet | One spin (sidereal day) | Sunrise to sunrise (solar day) | Year | Notes |
|---|---|---|---|---|
| Mercury | 58 d 15 h | 176 Earth days | 88 Earth days | A day (sunrise to sunrise) lasts two Mercury years |
| Venus | 243 Earth days (backwards) | 116.75 Earth days | 224.7 Earth days | Spins backwards: the Sun rises in the west |
| Earth | 23 h 56 min 4 s | 24 h | 365.25 days | |
| Mars | 24 h 37 min | 24 h 39 min 35 s (a "sol") | 687 Earth days (668.6 sols) | See the time on Mars now |
| Jupiter | 9 h 56 min | 9 h 56 min | 11.86 Earth years | Shortest day in the solar system |
| Saturn | 10 h 34 min | 10 h 34 min | 29.46 Earth years | Measured from ring waves in 2019 |
| Uranus | 17 h 14 min (backwards) | 17 h 14 min | 84 Earth years | Tilted on its side: each pole gets 42 years of daylight |
| Neptune | 16 h 6 min | 16 h 6 min | 164.8 Earth years | Has orbited the Sun once since its discovery in 1846 |
| Pluto (dwarf planet) | 6 d 9 h (backwards) | 6 d 9 h | 248 Earth years | |
| The Moon | 27.3 days | 29.5 days | 27.3 days (around Earth) | Always shows the same face to Earth |
Why two kinds of day?
A sidereal day is one full spin relative to the distant stars. A solar day is the time from one noon to the next. Because a planet also moves along its orbit while it spins, it has to turn a little extra for the Sun to come back to the same spot. On Earth that extra is about 4 minutes, which is why the sidereal day is 23 h 56 min while our clocks use 24 hours. See sidereal time.
On slow-spinning planets the difference is huge. Mercury spins once every 58.6 Earth days, but because it orbits the Sun so fast, sunrise to sunrise takes 176 Earth days, two of its years.
How long is a day on Mars?
A Martian day, called a sol, is 24 hours 39 minutes 35 seconds, only about 40 minutes longer than ours. NASA's rover teams have lived on Mars time, shifting their schedules 40 minutes later every day. A Martian year is 687 Earth days, or 668.6 sols, so Mars has seasons nearly twice as long as Earth's. See the current time on Mars.
How long is a year on each planet?
The farther from the Sun, the longer the year. Someone who is 30 on Earth would be about 125 in Mercury years, 16 in Mars years, 2.5 in Jupiter years and only about 1 in Saturn years. Neptune has completed just one orbit since it was discovered in 1846.
Questions people ask
How long is a day on Mars?
A Martian solar day, or sol, is 24 hours 39 minutes 35 seconds. One full spin relative to the stars takes 24 hours 37 minutes.
How long is a year on Mars?
687 Earth days, which is 668.6 Martian sols, or about 1.88 Earth years.
How long is a day on Jupiter?
About 9 hours 56 minutes, the shortest of any planet in the solar system.
How long is a day on Saturn?
About 10 hours 34 minutes. It was hard to measure because Saturn has no solid surface; scientists finally pinned it down in 2019 using waves in its rings.
Which planet has the longest day?
Venus takes 243 Earth days to spin once, longer than its 225-day year. Measured sunrise to sunrise, though, Mercury's day is the longest at 176 Earth days.
How long is a day on Uranus?
About 17 hours 14 minutes. But Uranus is tipped on its side, so near the poles the Sun stays up for about 42 years and then sets for 42 years.
Last updated October 23, 2026.