For centuries, astronomers faced the challenge of classifying objects in space based on their appearance. When observing an object that is orbiting a star at a distance, they would often assume it ...

rotation. Here’s the puzzle: That is about 6 minutes, or one percent, longer than the radio rotational period measured by the Voyager 1 and Voyager 2 spacecraft, which flew by Saturn in 1980 and 1981.

A day on Uranus just got slightly longer, thanks to more accurate measurements of its rotation period that should help scientists plan missions to probe the gas giant. Figuring out the rotation period ...

Planetary scientists have pinpointed the rotation period of Uranus — and it’s 28 seconds longer than they thought it was 1. Like other gas-giant planets, Uranus doesn’t have a rocky surface to look at ...