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In this image released by NASA on July 20, 2009, evidence of a large impact on Jupiter's south polar region can be seen. ((NASA/JPL/Associated Press))

Jupiter has been whacked again. An amateur astronomer in Australia peering at the giant gas planet Thursday reported witnessing a bright flash from an object hitting the Jovian surface and apparently burning up in the atmosphere.

Anthony Wesley, a computer programmer with a good reputation among professional astronomers, reported the cosmic collision to professional and amateur sky-gazers. The discovery was later confirmed by another amateur astronomer in the Philippines.

"When I saw the flash, I couldn't believe it," said Wesley. "The fireball lasted about two seconds and was very bright."

Wesley gained fame last year when he spotted a scar the size of the Pacific Ocean near Jupiter's south pole, believed to have been caused by an asteroid smacking into the planet. Using an infrared telescope on Hawaii, NASA scientists found evidence that Jupiter was apparently struck near its south pole.

The latest hit near the equator has not left any visible mark so far, but astronomers are on the lookout.

The absence of a detectable gash and the short impact time have led scientists to believe Jupiter was likely struck by a meteor.

"We've never seen a meteor slam into Jupiter," said Glenn Orton of NASA's Jet Propulsion Laboratory.

The latest collision should give astronomers a better idea of the size of debris floating in the outer solar system. In 1994, Jupiter was bombarded by pieces of the comet Shoemaker-Levy 9.