University of Leicester | American Geophysical Union | 2017 Apr 11
Massive aurorae-generated weather system revealed by astronomersGreat Cold Spot comparable in scale to famous Great Red Spot (24,000 km west-east and 12,000 km north-south); the phenomenon, only recently observed, may have existed for thousands of years; first direct evidence of a sustained weather system generated by polar aurorae and opens possibility on other planets.
A second Great Spot has been discovered on Jupiter by University of Leicester astronomers, rivaling the scale of the planet’s famous Great Red Spot and created by the powerful energies exerted by the great planet’s polar aurorae.
Dubbed the ‘Great Cold Spot,’ it has been observed as a localised dark spot, up to 24,000 km in longitude and 12,000 km in latitude, in the gas giant’s thin high-altitude thermosphere, that is around 200K (Kelvin) cooler than the surrounding atmosphere, which can range in temperature between 700K (426°C) and 1,000K (726°C). ...
“The Great Cold Spot is much more volatile than the slowly changing Great Red Spot, changing dramatically in shape and size over only a few days and weeks, but it has re-appeared for as long as we have data to search for it, for over 15 years,” Stallard said. “That suggests that it continually reforms itself, and as a result it might be as old as the aurorae that form it – perhaps many thousands of years old.”
The Great Cold Spot is thought to be caused by the effects of the magnetic field of the planet, with the massive planet’s spectacular polar aurorae driving energy into the atmosphere in the form of heat flowing around the planet. ...
The Great Cold Spot in Jupiter's upper atmosphere - Tom S. Stallard et al
- Geophysical Research Letters (online 10 Apr 2017) DOI: 10.1002/2016GL071956