Saturn's rings, imaged based on radio data from NASA's Cassini spacecraft. Green indicates regions with particles smaller than 5 centimeters; purple is where no particles are that small. The white ...

Tracking the rotation speed of solid planets, like the Earth and Mars, is a relatively simple task: Just measure the time it takes for a surface feature to roll into view again. But giant gas planets ...

If star-hopping aliens ever visited our solar system, Saturn is probably the planet they'd remember. The seven giant rings circling its equator make Saturn the most distinct planet orbiting the sun.