Scientists find large, new storm on Neptune

Aug. 4 (UPI) -- Scientists have discovered a storm system on the surface of Neptune near the planet's equator that is nearly the same size as Earth.

Researchers at the W.M. Keck Observatory, on Maunakea, Hawaii, discovered the massive storm system, which is about 5,600 miles long, one-third the size of Neptune's radius, and extends about 30 degrees in latitude and longitude.

"Seeing a storm this bright at such a low latitude is extremely surprising," Ned Molter, a graduate student at University of California, Berkeley, who spotted the storm complex during a test run of twilight observing at W. M. Keck Observatory, {link:said in a news release: "http://www.keckobservatory.org/recent/entry/new_storm_makes_surprise_appearance_on_neptune" target="_blank"). "Normally, this area is really quiet and we only see bright clouds in the mid-latitude bands, so to have such an enormous cloud sitting right at the equator is spectacular."

Scientists initially believed the storm system was the same Northern Cloud Complex that was seen in 1994 by the Hubble Space Telescope, after the Great Dark Spot that Voyager 2 captured in 1989.

However, measurements of its location did not match, showing that the cloud complex is different from the Hubble-shot system.

"Historically, very bright clouds have occasionally been seen on Neptune, but usually at latitudes closer to the poles, around 15 to 60 degrees north or south," Professor Imke de Pater, of UC Berkeley's Astronomy Department, said. "Never before has a cloud been seen at, or so close to the equator, nor has one ever been this bright."

Scientists believe a huge, high-pressure, dark vortex system may be what's causing the cloud cover because as gases rise up in a vortex, they cool down and form clouds.

"This big vortex is sitting in a region where the air, overall, is subsiding rather than rising," de Pater said. "Moreover, a long-lasting vortex right at the equator would be hard to explain physically. This shows that there are extremely drastic changes in the dynamics of Neptune's atmosphere, and perhaps this is a seasonal weather event that may happen every few decades or so."

Researchers observed the storm system getting larger between June 26 and July 2.