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.

2004 October 18


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Southern Saturn from Cassini
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: What happens to Saturn's pervasive clouds at its South Pole? Visible in the above image of Saturn are bright bands, dark belts and a dark spot right over the South Pole. The above image in infrared light spans over 30,000 kilometers and was taken early last month by the robot Cassini spacecraft currently orbiting Saturn. Saturn's atmosphere is about 75 percent hydrogen, 25 percent helium, and small amounts of heavier compounds including water vapor, methane, and ammonia. The relatively low gravity at Saturn's cloud tops result in a thicker haze layer, which in turn makes atmospheric features blurrier than Jupiter.

Tomorrow's picture: distant disks


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