Jupiter has the shortest day of any planet in the Solar System, rotating once in about 10 hours.
Jupiter’s rapid rotation gives it a sidereal rotation period of roughly 9 hours 56 minutes. Because the planet is made mostly of hydrogen and helium rather than solid rock, it does not rotate as a single rigid body: different latitudes in its atmosphere move at different speeds. Astronomers call this differential rotation.
The fast spin contributes to Jupiter’s prominent equatorial bulge. Its equatorial diameter is larger than its polar diameter, and powerful jet streams divide the cloud tops into alternating bands. The planet’s famous Great Red Spot is a long-lived storm within this dynamic atmosphere.
Jupiter is the largest planet and the fifth from the Sun. Its day is shorter than Saturn’s, even though Saturn is also a rapidly rotating gas giant. Measuring a day on a gaseous planet requires specifying the reference used, which is why sources may give slightly different values for atmospheric features and the planet’s interior radio-emission rotation.