Ring ripples reveal how long a day lasts on Saturn

The giant planet rotates once every 10 hours and 33 minutes

Saturn

CATCH A WAVE  Ripples in Saturn’s rings, shown in this image from the Cassini spacecraft, revealed the length of a day on the gas giant.

Space Science Inst., JPL-Caltech/NASA

You can’t tell how fast Saturn is spinning by watching the clouds swirling at its surface.