Jupiter Adds a Feature

Mauna Kea, Hawai’i — Jupiter’s got a brand new mark. Something slammed into the gas giant leaving a dark bruise in the planet’s atmosphere, scientists at Keck Observatory confirmed early on the morning of July 20 Hawaiian Standard Time.

The observation, made with the Keck II telescope, marks only the second time astronomers have seen such an impact on the planet. The first collision occurred 15 years ago, when more than 20 fragments of comet Shoemaker-Levy 9 (SL9) collided with Jupiter.

The SL9 impact events were well-studied in 1994, and many theories were subsequently developed based on the observations. “Now we have a chance to test these ideas on a brand new impact event,” said Paul Kalas, one of the University of California Berkeley (UCB) astronomers who helped observe the latest impact.

Kalas, along with Michael Fitzgerald of Lawrence Livermore National Lab and UCLA, happened to have observing time on the Keck II telescope early on the morning of Monday July 20, 2009. The two were searching for the Jupiter-like planet, Fomalhaut b, which orbits the star Fomalhaut. The star is located roughly 25 light years from Earth in the direction of the constellation Piscis Austrinus.

The astronomers decided to observe Jupiter after hearing of Australian amateur astronomer Anthony Wesley’s discovery of the planet’s new feature, which they read about on the blog of UCB and SETI Institute astronomer Franck Marchis. Together, the group of UC astronomers collaborated on how best to make the observations of the new feature. Fitzgerald then performed the observations with the help of Keck Observatory astronomer Al Conrad.

“The fact that [the feature] shows up so clearly means that it’s associated with high-altitude aerosols as seen in the Shoemaker-Levy impacts,” noted James Graham of UCB, who also assisted with the new observations as well as the observations taken during the SL9 event in 1994. According to the new data, an impact must have created Jupiter’s latest feature, the team of astronomers said.