Second ‘Great Spot’ found at Jupiter, cold and high up
Astronomers said the colossal dark expanse is 15,000 miles across and 7,500 miles wide – plenty big enough to swallow Earth.
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. Here, it is seen in July of 1995 and continues to reappear until 15 years later, in December of 2000. Auroras on Jupiter are fueled by a slow, stead supply of gases from the volcanoes of its moon, Io. Jupiter has the most powerful magnetosphere in our solar system, at least 10 times as powerful as Earth’s. But at the newly-discovered Great Cold Spot, temperatures are about 200 degrees Kelvin cooler than the surrounding atmosphere (73 degrees Celsius, or 100 degrees F). The CRIRES instrument on the Very Large Telescope (VLT) spotted the phenomenon. This offered an unprecedented level of detail when analyzing Jupiter’s sub-auroral 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.
The finding shows that Jupiter’s atmosphere is much more complex than we have anticipated. “So the aurora are actually a visual queue of a current that flows from the surrounding space environment into the atmosphere, forming an electric circuit”.
The Great Cold Spot might have some company too. “The detection of a localized region of cooling within the upper atmosphere is unexpected”, the authors of a new study, published in Geophysical Research Letters, reported this week.
But the feature always pops up in more than 15 years of data. The cold spot experience a dramatic change in size and shape over a few days or weeks. It was believed to be the only Great Red Spot on the planet. However, the Great Cold Spot can not be seen clearly until these images are saturated so that the entire aurora becomes white, as shown on the right.
Brit scientists discovered the new “cold spot” sweeping across the northern hemisphere of Jupiter.
Jupiter’s got a second giant spot.
“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. Astronomers say the Great Red Spot of Jupiter might have a subtle counterpart now being called the Great Cold Spot. With the Juno spacecraft currently in orbit around Jupiter, and with its instruments collecting valuable atmospheric data, the researchers now have an opportunity to find more of these mysterious weather features. The cold patch sometimes shrinks and disappears, only to appear again around periods of bright aurorae.