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“Great Cold Spot” Discovered on Jupiter

The ancient storm was hiding in plain sight

smithsonian.com

When you think of Jupiter, it’s likely you see red—the planet’s iconic Big Red Spot, that is. But it turns out that the gigantic red gyre isn’t the only great spot on Jupiter. As the Associated Press reports, scientists have found another spot on the gas giant: one that’s big, cold, and high up on the planet’s north pole.

The Great Cold Spot, as it’s being called, was spotted, as it were, by researchers using the Very Large Telescope. Located in Chile’s dark, high-altitude Atacama Desert, the telescope array is the world’s most cutting-edge optical instrument and gives scientists a better-than-ever chance to study the night sky.

With the help of that mammoth window to space, they were able to make observations of a previously unknown region at the top of Jupiter. They describe the spot in a new paper published in the journal Geophysical Research Letters.

The region isn’t a spot per se; it’s weather. Like the Great Red Spot, which is thought to be the product of a massive ongoing storm in Jupiter’s violent, gaseous atmosphere, the Great Cold Spot seems to be a weather system. Like its cousin, it’s really big—nearly 15,000 miles in longitude and 7,500 miles in latitude. That makes it bigger than Earth. And it's extremely cold compared to the rest of the atmosphere.

Scientists have been watching the spot for years without knowing it. When they compared the Very Large Telescope array’s analysis of the planet’s hydrogen—thought to fuel the planet’s crazy weather—with data from NASA’s Infrared Telescope Facility in Hawaii, they realized that the colder temperatures at the planet’s poles are pretty consistent.

The spot can’t be seen with the human eye. Rather, it’s visible on infrared readings as a kind of dark oval on top of Jupiter’s bright upper atmosphere. Though it seems to have shifted dramatically over the years—and is now thought to have existed since the planet was formed—it’s always in the same spot. That’s because Jupiter’s storms don’t have an actual planetary surface to slow them down.

Scientists can’t see what’s beneath the planet’s swirling, gaseous atmosphere, but their best guess is that it’s nothing like Earth, where all of the gas and dust that formed the planet eventually settled down to into things like land and water. Jupiter hasn’t been that lucky—its vortices appear to get continually fueled by radiation that sucks its surrounding atmosphere into it again and again. And the data collected by researchers suggests that the just-discovered cooler spot exists thanks to energy from Jupiter’s polar auroras.

Now, says the research team in a press release, they’ll look for other features in the upper atmosphere. They’ll have help: NASA’s Juno spacecraft is swirling around the planet as we speak, and researchers could use the orbiter’s data to learn even more about the Great Cold Spot and other storms. Get ready to update your mental map of the gas giant as new data comes in.

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