Secrets of Jupiter's Great Red Spot Revealed in New Weather Map
New thermal images from ESO’s Very Large Telescope (VLT) and other ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter’s Great Red Spot. The image on the left was obtained with the VISIR on the VLT in Chile on 18 May 2008. The image on the right was obtained by the NASA/ESA Hubble Space Telescope on 15 May 2008.
Credit: ESO/NASA/JPL/ESA/L. Fletcher

New images have revealed an unprecedented look at the swirling winds inside Jupiter's famed Great Red Spot and allowed scientists to build the first-ever detailed weather map of the giant storm?s insides.

"This is our first detailed look inside the biggest storm of the solar system," said Glenn Orton of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the leader of the team that studied Jupiter's giant spot.

Orton and his team looked at thermal images of the Great Red Spot taken with the European Southern Observatory's Very Large Telescope (VLT) in Chile. The images revealed that the reddest colour of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet.

The observations will be detailed in the journal Icarus and give scientists a sense of the circulation patterns within the solar system?s best-known storm system.

"We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated," Orton said.

Jupiter?s Great Red Spot is at least hundreds of years old and has been observed by astronomers on Earth since the 19th century. The storm is massive, and is large enough to fit three entire Earths inside.
The VLT images allow astronomers to map the Great Red Spot?s temperature, aerosols and ammonia within and surrounding the storm and chart how they change with time. The years VLT observations, coupled with those from other observatories, reveal how the storm is incredibly stable despite turbulence, upheavals and close encounters with other anticyclones that affect the edge of the storm system.

Jupiter also has a Little Red Spot that formed in 2000. In 2008, a third red spot that had previously been a white, oval-shaped storm was seen on Jupiter's surface. But it is the Great Red Spot that dominated attention in the new study.

The Great Red Spot is a cold patch on Jupiter that averages about minus 256 degrees Fahrenheit (minus 160 degrees Celsius).

"One of the most intriguing findings shows the most intense orange-red central part of the spot is about 3 to 4 degrees warmer than the environment around it," said team member Leigh Fletcher of the University of Oxford in England.

This temperature difference might not seem like a lot, but it is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm. Not only that, but on other parts of Jupiter, the temperature change is enough to alter wind velocities and affect cloud patterns in the belts and zones.

"This is the first time we can say that there?s an intimate link between environmental conditions ? temperature, winds, pressure and composition ? and the actual color of the Great Red Spot," Fletcher said. "Although we can speculate, we still don?t know for sure which chemicals or processes are causing that deep red color, but we do know now that it is related to changes in the environmental conditions right in the heart of the storm."

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