Jupiter has a ‘Great Cold Spot’ to go with its red spot

Jupiter is intensely studied because it’s the closest of our solar system’s gas giants, and it also happens to be the largest. Then there’s that entourage of moons, which are fascinating in their own right. Despite all the attention Jupiter has gotten over the years, it’s still finding ways to surprise us. Astronomers say the Great Red Spot of Jupiter might have a subtle counterpart currently being called the Great Cold Spot.

The Great Red Spot is a spinning vortex just south of Jupiter’s equator with a diameter of about 14,000 by 40,000 kilometers (8,699 by 24,854 miles). It has been observed continuously for 187 years, but scientists suspect it has existed much longer. The technology to make out patterns on Jupiter was lacking in past centuries, but it’s believed that some observations between 1665 and 1713 sighted the same storm raging in the planet’s atmosphere. Seeing the Great Red Spot was a simple matter of building a sufficiently powerful telescope. But the Great Cold Spot is more subtle.

Jupiter’s Great Red Spot, taken by Voyager 1.

The cold spot was discovered through careful examination of historic data on the Jovian atmosphere. Astronomers say the Great Cold Spot is 12,000 by 24,000 kilometers (7,456 by 14,912 miles) in size, which is in the same neighborhood as the Great Red Spot (it has been shrinking in recent decades). The key difference here, and the reason this feature has not been discovered previously, is that Jupiter’s Great Cold Spot does not show up in the visible spectrum. It’s an area of markedly colder temperatures.

Jupiter’s atmosphere is between 700 and 1,000 Kelvin (800 to 1340 Fahrenheit), and the Great Cold Spot is about 200 Kelvin (360 degrees Fahrenheit) colder than the surrounding gas. No one is quite sure what’s causing this vortex of chilled gas to form, though. There’s some speculation that it could be related to the powerful auroras that drive energy through Jupiter’s atmosphere. The Great Cold Spot seems to ebb and flow more than the Great Red Spot. Sometimes it’s undetectable, then it’ll come back with changes to shape and position (see below).

The Great Cold Spot over time.

The patterns of heat dispersal in the Jovian atmosphere might naturally result in the formation of cold spots like this. Astronomers hypothesize that The Great Cold Spot has been recurrent in the Jovian atmosphere for thousands of years. They might be able to confirm this with the help of NASA’s Juno probe, which is currently orbiting the gas giant. It will complete several dozen flybys of Jupiter of the next few years, and several of them should take it close to the Great Cold Spot.

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