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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

See Explanation. Clicking on the picture will download the highest resolution version available.

Persistent Saturnian Auroras

Explanation: Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's South Pole simultaneously as Cassini closed in on the gas giant in January 2004. Hubble snapped images in ultraviolet light , while Cassini recorded radio emissions and monitored the solar wind . Like on Earth, Saturn's auroras make total or partial rings around magnetic pole s. Unlike on Earth, however, Saturn's auroras persist for days, as opposed to only minutes on Earth . Although surely created by charged particles entering the atmosphere, Saturn's auroras also appear to be more closely modulated by the solar wind than either Earth's or Jupiter's auroras . The above sequence shows three Hubble images of Saturn each taken two days apart.

Date June 22, 2014
Credit Image Credit: J. Clarke ( Boston U. ) & Z. Levay ( STScI ), ESA , NASA
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.