The reddest part of Jupiter’s Great Red Spot corresponds to a warm core within this otherwise cold storm system.
The discovery comes from new thermal images taken by ground-based telescopes that have enabled scientists to make the first detailed interior weather map of the Solar System’s biggest storm.
The international team, including scientists from Oxford University and NASA JPL, used thermal images from the Very Large Telescope (Chile), Gemini Observatory telescope (Chile) and Japan’s Subaru telescope (Hawaii). They report their findings in the journal Icarus.
‘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 colour of the Great Red Spot,’ lead author Leigh Fletcher, from Oxford University’s Department of Physics, told me.
‘Although we can speculate, we still don’t know for sure which chemicals or processes are causing that deep red colour, but we do know now that it is related to changes in the environmental conditions right in the heart of the storm.’
As well as this warm ‘heart’ the images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet.
One of the most intriguing findings is that the most intense orange-red central part of the spot is about 3 to 4 Kelvin warmer than the environment around it.
Leigh explains that while this temperature differential might not seem like a lot 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 our first detailed look inside the biggest storm of the solar system,’ said Glenn Orton, a senior research scientist at NASA’s Jet Propulsion Laboratory, one of the authors. ‘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.’
Unlocking the secrets of Jupiter’s giant storm systems will be one of the targets for infrared spacecraft observations from future missions including NASA’s Juno and the NASA/ESA Europa-Jupiter System Mission concept.
Dr Leigh Fletcher is based at Oxford University’s Department of Physics