Neptune boasts some of the strangest weather in the solar system. The sun’s eighth planet holds the record for the fastest winds observed on any world, with speeds cutting through the atmosphere upward of 1,100 miles per hour, or 1.5 times the speed of sound. Scientists still don’t know exactly why its atmosphere is so tumultuous. Their latest glimpse of Neptune provided even more reason to be confused. From a report: The Hubble Space Telescope identified a storm in 2018, a dark spot some 4,600 miles across. Since that time, it appears to have drifted toward the equator but then swooped back up north, according to the latest Hubble observations. It also has a smaller companion storm, nicknamed Dark Spot Jr., that scientists think might be a chunk that broke off the main storm. These inky vortexes stand out against the dizzying cerulean blue of the planet, but while they’re dazzling to see, their life spans are short, making them even more challenging to study.
This is not the first time Neptune’s dark spots have behaved so strangely. When the Voyager 2 spacecraft flew past the planet in 1989, (still the only spacecraft to do so) it observed two storms. One was the original Dark Spot, a large vortex about the size of the Earth. It too had a companion, a smaller, fast moving storm nicknamed Scooter. The first observed Dark Spot also seemed to move south and then back to the north. “When we were tracking the great dark spot with Voyager, we saw it oscillating up and down in longitude,” said Heidi Hammel, a member of the imaging team of the Voyager 2 space probe and currently the vice president for science at the Association of Universities for Research in Astronomy. “We had enough time on Voyager, that we were able to track the feature for something like four to five months leading up to the flyby. That storm was huge, a big monster,” as big as planet Earth.
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