Picture of the Week—Jupiter’s New Spot

Australian amateur astronomer Anthony Wesley was the first person to spot the new spot on Jupiter, on July 19th. Professional astronomers quickly confirmed the sighting and started aiming their powerful telescopes at the gas giant. Scientists now say that a small comet probably created the scar, which is about the size of the Pacific Ocean.

Although the spot appears black in visible-wavelength images, it glows in infrared, like in the image above (the new spot is the one in the bottom center). The picture was produced by astronomers using the Gemini North telescope on Mauna Kea in Hawai'i.

"We utilized the powerful mid-infrared capabilities of the Gemini telescope to record the impact's effect on Jupiter's upper atmosphere," said Imke de Pater (University of California, Berkeley). "At these wavelengths we receive thermal radiation (heat) from the planet's upper atmosphere. The impact site is clearly much warmer than its surroundings, as shown by our image taken at an infrared wavelength of 18 microns."

The Gemini images were obtained with the MICHELLE spectrograph/imager, yielding a series of images at 7 different mid-infrared wavelengths. Two of the images (8.7 and 9.7 microns) were combined into a color composite image by Travis Rector at the University of Alaska, Anchorage to create the final false-color image. By using the full set of Gemini images taken over a range of wavelengths from 8 to 18 microns, the team will be able to disentangle the effects of temperature, ammonia abundance, and upper atmospheric aerosol content. Comparing these Gemini observations with past and future images will permit the team to study the evolution of features as Jupiter's strong winds disperse them.

This is only the second time that astronomers have been able to see the effect of an impact on the Jupiter surface. They watched the planet closely when the Shoemaker-Levy 9 comet broke apart and collided with the gaseous surface 15 years ago this month.

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Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.