Scientists find 2nd 'Great Spot' on Jupiter

Another "Great Spot" has been found at Jupiter, this one cold and high up.

New weather system dubbed the 'Great Cold Spot' by researchers

Energy from auroras, seen here above Jupiter's north pole, form what is being called the Great Cold Spot. (NASA/ESA)

Another "Great Spot" has been found at Jupiter, this one cold and high up.

Scientists reported Tuesday that the dark expanse is 24,000 kilometres across and 12,000 kilometres wide. It's in the upper atmosphere and much cooler than the hot surroundings, thus the name Great Cold Spot. And unlike the giant planet's familiar Great Red Spot, this newly discovered weather system is continually changing in shape and size: it's formed by the energy from Jupiter's polar auroras.

A British-led team used a telescope in Chile to chart the temperature and density of Jupiter's atmosphere. When the researchers compared the data with thousands of images taken in years past by a telescope in Hawaii, the Great Cold Spot stood out. It could be thousands of years old.

These images show how the Great Cold Spot changes dramatically in shape and size on different days. Because the feature is dynamic, changing over both daily and yearly timescales, it is likely a weather system in a constant state of change. (Based on data from IRTF/NASA)

"The Great Cold Spot is much more volatile than the slowly changing Great Red Spot … but it has reappeared for as long as we have data to search for it, for over 15 years," the University of Leicester's Tom Stallard, lead author of the study, said in a statement.

Stallard said Jupiter's upper atmosphere may hold other features. Scientists will be on the lookout for them while also studying the Great Cold Spot in greater detail, using ground telescopes as well as NASA's Juno spacecraft in orbit around Jupiter, he said.

The study was published in Geophysical Research Letters, a journal of the American Geophysical Union.