Bottom: Infrared picture of the Red Spot taken by VLT in Chile on 18 May 2008. Top: Visible-light image, which was obtained by the NASA/ESA Hubble Space Telescope on 15 May 2008. These images show the interaction of three of Jupiter's largest storms — the Great Red Spot and two smaller storms nicknamed Oval BA and Little Red Spot.
Credit: ESO/NASA/JPL/ESA/L. Fletcher
SYDNEY: Jupiter's Great Red Spot is "extremely complicated", with a core that is warmer and spins in the opposite direction, scientists have found.
The Great Red Spot (GRS) is a storm three times the size of Earth, which spins mostly counter clockwise. It has persisted since at least 1831, and is the most recognisable feature on the striped planet.
A 13-year international study, appearing in the journal Icarus, used some of the biggest ground-based telescopes to link colours within the spot with its temperature, winds, pressure and composition of the gases.
Biggest storm in the Solar System
Infrared images made by the four eight-metre-wide telescopes of the European Southern Observatory's (ESO) Very Large Telescope in northern Chile and other telescopes were compared with the Hubble Space Telescope's visual images to give a level of detail better than that obtained by NASA's Galileo and Cassini spacecraft, which last visited the gas giant in 2003.
"This is our first detailed look inside the biggest storm of the Solar System," says planetary scientist Glenn Orton from NASA's Jet Propulsion Laboratory in California, who led the research team.
"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."
Core is even redder
The newly discovered core, which the team first spotted in 2005, rotates weakly clockwise and is three to four degree warmer than the spot's average temperature of -160 degrees Celsius.
It also glows redder than the rest of the spot. The scientists also found darker bands at the edges of the spot where gases descend into the interior.
"The warm core was there every time we looked, over a three year period. So it seems to be a long-lived feature of the storm, and the next generation of dynamical models will be needed to explain why this warm heart is present, and whether it's typical of storm systems on gas giant planets," the study's lead author, planetary scientist Leigh Fletcher from the University of Oxford in Britain told Cosmos.
As detailed as Earth storms
Australian planetary scientist Jeremy Bailey said the level of detail gathered by the study meant that astronomers could study Jupiter's GRS in the same way that meteorologists studied the storm systems of Earth.
""This storm system is similar to those on Earth, but they are transient events while the Great Red Spot has been around for hundreds of years," says Bailey.
But while the study makes progress, Bailey said astronomers hadn't yet found all the answers as to what generates such massive storms on gas planets.
Fletcher agrees. "Cues of the GRS origin might be better gleaned from its companion, Oval BA, which reddened in 2005/06 and is now the second largest storm system on Jupiter. So Oval BA might tell us about the birth of giant red storms, whereas the GRS tells us about why they're stable for such long periods of time," he says.
