Astronomy Picture of the Day

Explanation: Saturn's Rings are one of the most spectacular sights in the solar system. Still, this image from the Hubble Space Telescope offers a striking view of another kind of ring around Saturn - pole encircling rings of ultraviolet aurora. Towering more than 1,000 miles above the cloud tops, these Saturnian auroral displays were thought to be analogous to Earth's. But following the ebb and flow of Saturn's aurora, with the Hubble's cameras and instruments onboard the Cassini spacecraft, researchers are now reporting some surprising results. In this false-colour image made in ultraviolet light, the dramatic red aurora identify emission from atomic hydrogen, while the more concentrated white areas are due to hydrogen molecules.