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The comet or asteroid hit near Jupiter's South Pole. The color inset shows the area magnified; the impact site is the irregular black patch below the white oval of a storm.
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Images courtesy of NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team.

Impact on Jupiter - July 2009

On the night of July 19, 2009, Anthony Wesley noticed a dark splotch on Jupiter that hadn't been there before. Wesley, an amateur astronomer in Australia, had discovered the remnants of a huge impact on Jupiter. A comet or asteroid had collided with the giant planet, leaving a dark "scar" in Jupiter's atmosphere where it had exploded.

Since nobody saw the object that hit Jupiter before the collision, scientists aren't sure whether it was a comet or an asteroid. Astronomers estimate that the object was a few hundred meters across. The impactor exploded in Jupiter's upper atmosphere, creating a cloud of debris about the size of Mars. The explosion left a dark smear, which is about as large as the Pacific Ocean, in Jupiter's atmosphere near the planet's South Pole.

This is the second time in recent decades that Jupiter has been struck by large objects. In July 1994 several fragments of Comet Shoemaker-Levy 9 crashed into the gas giant as astronomers looked on. Scientists had predicted that collision and were thoroughly prepared to view it. The more recent event caught astronomers by surprise, but thanks to the sharp eyes of one amateur observer the world was alerted shortly after the impact... and powerful telescopes including Hubble and Keck were able to capture images of the aftermath.

Last modified August 21, 2009 by Randy Russell.

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