Hubble Telescope Photographs Jupiter Impact Site
This Hubble picture, taken on 23 July, is the sharpest visible-light picture taken of the atmospheric debris from a comet or asteroid that collided with Jupiter on 19 July. This is Hubble's first science observation following its repair and upgrade in May. The image was taken with the new Wide Field Camera 3.
Credit: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colorado) and the Jupiter Comet Impact Team

The unexpected impact of some space object with Jupiter, creating a dark bruise in the gas giant?s atmosphere, proved a tempting enough target for scientists to put a hold on testing out the revamped Hubble Space Telescope and use its new camera to capture an image of the rare event.

The plan, first reported by Spaceflight Now, was carried out yesterday so that astronomers could use the 19-year-old Hubble's unique capabilities to get an image of the spot, probably caused by a comet, before too many days had passed since the impact and Jupiter's atmosphere distorted the shape.

The new Hubble image, released today, shows a lumpiness to the debris plume caused by turbulence in Jupiter's atmosphere. The image is a natural color image of Jupiter in visible light.

"It was important for Hubble to get an early look," said Hubble spokesman Ray Villard.

The dark spot was first noticed by chance by amateur astronomer Anthony Wesley in Australia on Sunday, July 19.

The bruise is near Jupiter's southern pole and is about the size of the Pacific Ocean, according to one astronomer's estimates.

The feature is reminiscent of the 1994 impact of Comet Shoemaker-Levy 9.

While astronomers don't know for sure what impacted Jupiter this time around, "the best guess is that it's a comet," the reasoning being that comets cross Jupiter's orbit while asteroids rarely do, Villard said.

While other telescopes (including the Keck II telescope and the Gemini Observatory, both in Hawaii) have trained their eyes on the spot in recent days, it was important for Hubble to take a look because "it's the sharpest at visible wavelengths," Villard told Hubble also has capabilities to look at ultraviolet wavelengths, which can show details of the impact debris that has been tossed high into Jupiter's atmosphere.

"It really was incumbent upon us to join with the other telescopes," Villard said.

Hubble was in the middle of testing and calibration of its new instruments, installed by astronauts during a service mission in May. Hubble managers decided that the impact event was rare enough and important enough to pause testing to get a look.

Recent glitches have delayed the commissioning of some instruments, but the new Wide Field Camera 3 is working fine.

"It's not fully calibrated, but it doesn't mean we can't take pictures," Villard said.

With the Hubble images complementing other telescope's efforts, astronomers hope to learn more about the dark spot and the impactor that caused it.

With the data astronomers have from the Shoemaker-Levy 9 impact, they can guess at some features of the likely comet. It is estimated to have been no bigger than half a kilometer and likely had thousands of times the energy of the Tunguska impact here on Earth, which generated a huge explosion over Siberia in 1908, flattening an area as big as a large city.

Hubble is slated to take more images of the new impact spot in the coming days, to help astronomers track its progress. In between pictures, the Hubble team should be able to resume testing and calibration of the camera.