Astronomers from University of California, Berkeley, recently spotted a low-altitude, bright, and massive new storm system as wide as Earth near the equator of Neptune, and it continued to shine brighter from June 26 through July 2.

While storm systems in outer planets are not really a strange sight, the newly discovered 9,000-kilometer-long storm stands out because of its location and the fact that it still persisted a month later, in late July.

"Seeing a storm this bright at such a low latitude is extremely surprising. 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," UC Berkeley graduate student Ned Molter said.

Molter is the Keck visiting scholar who first spotted the strange storm seen below.

Bright Clouds In Neptune Are Normal, Right?

According to astronomers, bright clouds are not a strange feature for ice giant Neptune but most, if not all, observations place the clouds near the poles. This is the first time astronomers have observed a long-lasting and bright storm raging so close to Neptune's equator so they are now looking into how it formed in its location and why it persists.

"Since it must have been around for a few weeks at least ... something must hold it together," UC Berkeley Astronomy Professor Imke de Pater said. Professor de Pater is Molter's advisor.

The astronomers are considering the possibility that a dark vortex may be behind — or more accurately, below — the storm but are finding it difficult to come up with explanations on how a long-lasting vortex could exist close to the equator. It is also tricky business trying to look deep into the atmosphere but, if a dark vortex is involved, that would explain why the storm system is taking a while to dissipate.

It is also possible that the storm is a huge convective cloud, but those usually dissipate in a week or so, hence a month-long convective cloud is still a strange, albeit possible, explanation.

"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," Professor de Pater said.

A Dark Vortex Could Be The Likely Explanation

Professor Michael Wong, another UC Berkeley astronomer who has studied dark vortices and their bright companion clouds in Neptune but who is not involved with the discovery, believes a vortex may be associated with the storm.

"We can't resolve enough detail to know, but this could be some type of wave activity associated with dark vortices," Professor Wong expressed.

If a vortex is really involved, Molter thinks that it could be located a few degrees north or south of the equator.

Molter's original objective as UC Berkeley's Keck visiting scholar was to develop a better method for twilight observations, but he and Professor de Pater have also resolved to see the mystery through.

"Now that we've discovered this interesting cloud complex in Neptune, Ned has a running start on a nice paper for his PhD thesis," de Pater expressed.

Both Molter and Professor de Pater will propose for more observation time at Keck Observatory to learn more about the bright storm system.