In a paper published today in Geophysical Research Letters, scientists led by the University of Leicester in the UK have found evidence for a huge dark storm on Jupiter that rivals the famous Great Red Spot in size.
It has been called the “Great Cold Spot”, and measures up to 24,000 kilometers (15,000 miles) in longitude and 12,000 kilometers (7,500 miles) in latitude, which is comparable to the Great Red Spot, even though it's shrinking.
The Great Cold Spot is found in the thin high-altitude thermosphere of the atmosphere, and is about 200 degrees Kelvin (-73°C) cooler than the surrounding atmosphere, which is between 700 degrees Kelvin (426°C) and 1,000 degrees Kelvin (726°C).
This new spot is not visible to the naked eye on the planet, but was instead found using infrared images from NASA’s InfraRed Telescope Facility at the Mauna Kea Observatory in Hawaii. The spot then appeared as an area of darkness against the hot environment of the surrounding atmosphere.
“This is the first time any weather feature in Jupiter’s upper atmosphere has been observed away from the planet’s bright aurorae,” said lead author Tom Stallard from the University of Leicester in a statement.
A computerized view of the Great Cold Spot. IRTF/NASA
Interestingly, the spot has persisted in the same place for the last 15 years, making it similar to other long-lasting storms on the gas giant. Jupiter’s aurora may play a part, being a more permanent feature than the aurorae we get on Earth.
However, the Great Cold Spot seems to be a lot more volatile than the Great Red Spot, which has persisted for 400 years. It dramatically changes shape over just a few days or weeks, but continues to reappear.
“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,” said Stallard.
It’s possible that there are other similar features in the upper atmosphere of Jupiter, too. And with NASA’s Juno spacecraft currently in orbit around Jupiter, we should be able to find out much more about this fascinating world than ever before.
Jupiter's aurora, seen here offset against the magnetic north pole, is thought to play a part. IRTF/NASA