The Great Red Spot of Jupiter is about twice the size of Earth, blows winds at speeds of about 400 mph, and has blemished the planet’s atmosphere for more than 350 years.
But the spot’s grandeur is matched only by its mystery: Jupiter is very far away — about 489 million miles — so few probes have ever visited the planet, let alone flown near its crimson-colored super-storm. In fact, the best views of the Great Red Spot most often come from NASA’s Hubble Space Telescope, which orbits Earth.
However, NASA’s Juno spacecraft is expected to fly over the Great Red Spot on July 10 and beam back the closest-ever views of biggest, baddest storm in the solar system.
“This monumental storm has raged on the solar system’s biggest planet for centuries,” Scott Bolton, a planetary scientist at the Southwest Research Institute in San Antonio and the Juno mission’s leader, said in a NASA statement. “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.”
The decked-out probe has photographed Jupiter’s poles for the first time, discovered atmospheric “rivers” of ammonia, watched 870-mile-wide cyclones swirl, recorded mysterious auroras, and probed deep into the planet’s thick cloud tops for evidence of a solid core.
Juno hasn’t yet taken close-up images of the Great Red Spot, however, because Jupiter rotates quickly (nearly once every 10 Earth hours) and the probe’s visits are fast and infrequent.
Juno’s orbit around Jupiter is elliptical, so it only swings by the planet once every 53.5 days. (NASA wanted to increase the frequency of these flybys to every two weeks, but that operation was scrubbed due to some sticky engine valves.) When it does get close, Juno accelerates to speeds of 130,000 mph over the planet’s surface. That minimizes the robot’s time inside Jupiter’s belts of electronics-damaging radiation, yet reduces observing time.