Humans have observed the Great Red Spot on Jupiter for at least 150 years, possibly even longer. Stargazers saw a spot through telescopes as early as the 17th century, but scientists can't say for sure if it's the same one. Regardless, NASA's Juno spacecraft will get the closest view ever captured of the planet's famous feature during a flyby on Monday.
"Jupiter's mysterious Great Red Spot is probably the best-known feature of Jupiter," Scott Bolton, Juno's principal investigator, said in a statement. "This monumental storm has raged on the solar system's biggest planet for centuries. Now, Juno and her cloud-penetrating science instruments will dive in to see how deep the roots of this storm go, and help us understand how this giant storm works and what makes it so special."
Juno launched from Cape Canaveral in Florida on August 5, 2011, and traveled more than 1.7 billion miles through interplanetary solar winds before safely entering the orbit of our solar system's largest planet just over a year ago. NASA has previously explored Jupiter with flybys (Pioneers 10 and 11 and Voyagers 1 and 2) and the Galileo orbiter, but Juno is the first space mission ever to enter a polar orbit around the planet. The spacecraft has been flying in 53-day orbits around Jupiter.
On Monday at 9:55 p.m. ET, Juno will get as close as 2,200 miles above the cloud tops when it reaches the point in its orbit nearest Jupiter's center. During the next 11 minutes and 33 seconds, it will travel another 24,713 miles and pass over the Great Red Spot at a height of about 5,600 miles. Scientists have never had the chance to study it at a closer range. All of Juno's instruments, including the JunoCam, will be on for the rare opportunity to collect more information about a spot that has piqued humans' curiosity for centuries.
NASA has called Jupiter's Great Red Spot "a swirling mystery" as recently as 2015, when the spacecraft was still en route toward the planet. The storm's winds reach speeds of up to 400 miles per hour, compared to the roughly 200 miles per hour of the largest, strongest hurricanes on Earth. Scientists still don't know enough about the storm or what gives it the reddish color, even though several have conducted lab experiments that simulate Jupiter's atmosphere to try to pinpoint an explanation. Amy Simon, an expert in planetary atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Maryland, explained that Jupiter and its iconic Great Red Spot could help scientists gain a better understanding of Earth's weather system, as well as those of worlds beyond our solar system.
"The Great Red Spot is basically the largest storm in the entire solar system," Bolton tells Newsweek. "It's bigger than the Earth. It was even bigger decades ago. It's very puzzling." Even though the storm has lasted so long and is so big, he explains, scientists don't know where the energy and power of the storm are coming from, or even what it looks like in great detail. Monday's flyby will likely help garner some new information that could help explain the phenomenon—such as making use, for example, of the microwave radiometer that can look through the clouds to the atmosphere below. Bolton says this will be one of multiple passes over the Great Red Spot, though it's unclear exactly when the next opportunity will arise.
The images Juno captures on Monday are bound to be stunning. Bolton can't say with certainty when the first will be released, as the spacecraft has to get farther from Jupiter and turn back toward Earth before data can be downlinked, but he predicts they'll be published by the weekend. They should be worth the wait.
"The images Juno has been able to return—Jupiter's like a piece of art," he says. "I expect that this Great Red Spot might be a piece of art."
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Stav is a general assignment staff writer for Newsweek. She received the Newswomen's Club of New York's 2016 Martha Coman Front ... Read more
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