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.

2021 June 27
The picture shows the Saturn in infrared light with aurora as imaged by the
orbiting Cassini spacecraft in 2007.  
Please see the explanation for more detailed information.

The Dancing Aurorae of Saturn
Image Credit: NASA, Cassini, VIMS Team, U. Arizona, U. Leicester, JPL, ASI

Explanation: What drives aurorae on Saturn? To help find out, scientists have sorted through hundreds of infrared images of Saturn taken by the Cassini spacecraft for other purposes, trying to find enough aurora images to correlate changes and make movies. Once made, some movies clearly show that Saturnian aurorae can change not only with the angle of the Sun, but also as the planet rotates. Furthermore, some auroral changes appear related to waves in Saturn's magnetosphere likely caused by Saturn's moons. Pictured here, a false-coloured image taken in 2007 shows Saturn in three bands of infrared light. The rings reflect relatively blue sunlight, while the planet itself glows in comparatively low energy red. A band of southern aurora in visible in green. In has recently been found that aurorae heat Saturn's upper atmosphere. Understanding Saturn's aurorae is a path toward a better understanding of Earth's aurorae.

Tomorrow's picture: paper moon eclipse

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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