What Hit Jupiter?

On July 19th, 2009, amateur astronomer Anthony Wesley of Australia noticed a new "black scar" on Jupiter. He reported his findings to professional scientists who confirmed that Jupiter was indeed hit by an unknown object and that the black scar is actually a debris field created from the impact.

Jupiter - July 23, 2009
Hubble Space Telescope
Wide Field Camera 3

Scientists all over the world have begun studying the impact site to look for clues to try and find out what hit Jupiter.

Using NASA Hubble Space Telescope imagery, scientists were able to measure the size of the scar to be about twice the size of the United States.

Comparing this new scar to the scars created during the 1994 impacts from the 21 fragments of the Comet Shoemaker-Levy 9, scientists estimate the size of the object that hit Jupiter to be approximately a few hundred meters in diameter.

Scientists are collecting data of the scar at different wavelengths to study the chemical composition and evolution of the debris cloud, which may provide clues about the impactor, as well as the atmosphere.


Increased levels of ammonia gas have been detected but are thought to have been brought up from below the clouds during the impact.

Due to Jupiter's strong winds, the 2009 impact scar will soon disappear into Jupiter just as the Shoemaker-Levy 9 clouds did in 1994. Until then scientists will continue to study the impact's debris and by comparing past and future images will be able to study Jupiter's strong winds high above the clouds.