February 22, 2005
The cosmos is full of spectacular things: ringed planets, exploding suns, rivers of stars across the night.
Persistent Saturnian Auroras
Birthday · February 22, 2005
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APOD published February 22, 2005. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
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 poles. 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.