Scientists probe Jupiter's raging storm

Astronomy

The thermal image at left charts temperature variations in three storms on Jupiter
Thermal images have charted the temperature of Jupiter's Great Red Spot in unprecedented detail, revealing that the very center of the spot is warmer than the outer edges. The readings reveal the meteorological mechanics behind the solar system's strongest storm.

We once thought that the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated, Glenn Orton, a researcher at NASA's Jet Propulsion Laboratory who headed up the research team behind the temperature study, said today in an image advisory from the European Southern Observatory.

The Great Red Spot, which is so wide three Earths could be lined up side by side across its breadth, has existed for hundreds of years. It's the most often-observed feature in our solar system, after the storms that form here on Earth, said the University of Oxford's Leigh Fletcher, who was lead author for the study appearing in the journal Icarus.

But it requires extraordinary resolution to measure the temperature differences within the spot. Not even NASA's Galileo spacecraft, which observed Jupiter from orbit for almost eight years, could detect the warm core. it was finally spotted using the VISIR mid-infrared spectrometer and imager on the ESO's Very Large Telescope in Chile.

I was almost in tears when I first saw the detail popping up in our first thermal images of Jupiter, because in minutes we were getting across the entire planet what it took us years of effort to get in little areas at the time with Galileo, Orton told me. These first observations were from the Subaru Telescope in Hawaii, which along with the Gemini South telescope in Chile contributed data to the research effort.

The Great Red Spot's intensely orange-red core is warm only in relative terms. Across the entire extent of the storm, temperatures average about 256 degrees below zero Fahrenheit (-160 degrees Celsius). But Fletcher said the core is 3 to 4 degrees C (5 to 7 degrees F) warmer than the area around it. That would be enough to explain the change in circulation, from counterclockwise at the edges to weakly clockwise in the core. What's more, the core material is sinking down while the outer material is welling up, Orton said.