A ‘Great Cold Spot’, a weather feature, has been discovered in Jupiter’s atmosphere—the planet’s second ‘Great Spot’ to be documented by scientists. The new findings are published in Geophysical Research Letters.
Jupiter is already known for having a Great Red Spot. The new one, named Great Cold Spot, has been discovered by a team of researchers from the University of Leicester. It is claimed to be the product of Jupiter’s polar aurorae.
The study marks the first time a weather feature has been found on Jupiter, more specifically in its upper atmosphere, the thermosphere, away from its bright aurorae, explains lead author Dr Tom Stallard. The Great Cold Spot is described as being a dark spot situated at a particular location: 24,000 km in longitude and 12,000 km in latitude. The temperature there is around 200K colder than the surrounding air, whose temperature range is between 700K (426ºC) and 1000K (726ºC).
According to Dr Stallard, the Great Cold Spot might have existed for millennia on end, as old as Jupiter’s aurorae. It is continually being reformed after it changes shape and size over days or weeks. It occurs when the polar aurorae of the planet drive heat energy into the atmosphere, resulting in a layer of cooling in the layer between the underlying atmosphere and space, the thermosphere.
The dark Great Cold Spot was spotted after the more than 13,000 images spanning over 40 nights were analysed with the equipment at the InfraRed Telescope Facility.
“What is surprising at Jupiter is that, unlike weather systems on Earth, the Great Cold Spot has been observed at the same place across 15 years. That makes it more comparable to weather systems in Jupiter’s lower atmosphere, like the Great Red Spot,” says Dr Stallard.
The professor continues to highlight the differences between the aurorae of Earth and Jupiter: the former undergo changes that result from solar activity while the latter entail gases released by the volcanic moon Io; Earth’s aurorae creates atmospheric flows that can circulate heat energy throughout the planet while the fast spin of Jupiter causes this energy to be trapped in closer proximity to the poles.
Now, the next step is to find other features in Jupiter’s atmosphere.
“The detection of the Great Cold Spot was a real surprise to us, but there are indications that other features might also exist in Jupiter’s upper atmosphere. Our next step will be to look for other features in the upper atmosphere, as well as investigating the Great Cold Spot itself in more detail,” says Dr Stallard.
The professor is positive that the next few years will bring a better understanding of the weather system identified on the huge planet.