We love Juno’s stunning new photos of Jupiter’s Great Red Spot as much as anyone, but when it comes to giant storms, the Great Red Spot has some stiff competition.
Neptune is a good breeding ground for storms because its atmosphere is incredibly windy — its winds can whip at nine times the strength of Earth’s peak winds and three times the strength of Jupiter’s. The Voyager 2 spacecraft and the Hubble Space Telescope have photographed a range of “Great Dark Spots” growing and shrinking on the planet.
But now, scientists have spotted an unusually large cluster of bright clouds on Neptune’s surface. The storm is a little smaller than Earth, at more than 5,500 miles across. And while the other storms spotted on Neptune have all been in the mid-latitudes, this one is surprisingly close to the planet’s equator.
Ned Molter, a graduate student at the University of California, Berkeley, spotted the storm from the Keck Observatory in Hawaii. But finding an incredible feature wasn’t even part of the plan: He and his adviser were there to develop protocols for observing during twilight, when astronomers are usually waiting for the sky to darken completely.
For such a large storm to stick together for a week, there has to be something holding it together. The scientists think that might be a dark vortex in Neptune’s lower atmosphere, which would funnel gas up to cool and form methane clouds. It could also be tied to Neptune’s decades-long seasons during its 165-year orbit around the sun.