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. Click on image for full size (68 Kb) Images courtesy of NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team.

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.

The comet or asteroid hit near Jupiter's South Pole. The color part of this picture shows the area of the impact magnified. There is a white, oval storm. Do you see the black patch below the white oval? That is where the comet or asteroid hit! Click on image for full size (68 Kb) Images courtesy of NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team.

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

Nobody saw the object it hit Jupiter. We don't know whether it was a comet or an asteroid. The comet or asteroid was probably a few hundred meters (less than a mile) across. It exploded in Jupiter's upper atmosphere. The explosion made a cloud of debris as big as the planet Mars! It also made a dark smear in Jupiter's atmosphere near the planet's South Pole. The dark smear is about as big as the Pacific Ocean.

Jupiter was hit by another comet not too long ago. In 1994 several pieces of Comet Shoemaker-Levy 9 crashed into Jupiter. Scientists knew that collision was coming. They were ready to watch it.

This time around astronomers didn't know that something was going to hit Jupiter. It is lucky that Anthony Wesley was watching. After Wesley reported the impact, lots of other astronomers pointed their telescopes at Jupiter. The Hubble Space Telescope snapped a nice picture. The Keck telescope in Hawaii also took a picture... in infrared "light". Those pictures will help scientists learn about large impacts.

The comet or asteroid hit near Jupiter's South Pole. The color part of this picture shows the area of the impact magnified. There is a white, oval storm. Do you see the black patch below the white oval? That is where the comet or asteroid hit! Click on image for full size (68 Kb) Images courtesy of NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team.

Anthony Wesley is an astronomer in Australia. One night in July 2009, Wesley noticed a dark spot on Jupiter that hadn't been there before. He had discovered the remains of a huge impact on Jupiter! A comet or asteroid had collided with the giant planet. The impact left a dark "scar" in Jupiter's atmosphere where the comet or asteroid had exploded.

Nobody saw the object it hit Jupiter. We don't know whether it was a comet or an asteroid. The comet or asteroid was probably a few hundred meters (less than a mile) across. It exploded in Jupiter's upper atmosphere. The explosion made a dark smear in Jupiter's atmosphere. The dark spot is near Jupiter's South Pole. The dark spot is about as big as the Pacific Ocean.

After Wesley reported the impact, lots of other astronomers pointed their telescopes at Jupiter. The Hubble Space Telescope snapped a nice picture. The Keck telescope in Hawaii also took a picture... in infrared "light". Those pictures will help scientists learn about large impacts. Jupiter was hit by another comet not too long ago. In 1994 several pieces of Comet Shoemaker-Levy 9 crashed into Jupiter.