Ring ripples reveal how long a day lasts on Saturn
The giant planet rotates once every 10 hours and 33 minutes
You can’t tell how fast Saturn is spinning by watching the clouds swirling at its surface. But ripples in its rings reveal how fast the planet rotates: Its day flies by in 10 hours, 33 minutes and 38 seconds.
“That’s a really fast clip,” says astronomer Christopher Mankovich of the University of California, Santa Cruz, who reports the rotation rate in the Astrophysical Journal on January 17. Saturn, with a radius of about 58,000 kilometers, is about nine times the size of Earth yet its day is less than half as long.