Sol appears to be evaporating Neptune's clouds

Original title: All of Neptune’s clouds have vanished – it may be because of the sun

Over the past few years, the white clouds that usually shroud Neptune’s surface have disappeared, and it may be because of changes in the sun’s activity over its 11-year cycle

Erandi Chavez at the University of California, Berkeley, and her colleagues tracked the cloud activity on Neptune from 1994 to 2022. They examined archival images from two ground-based astronomical observatories and the Hubble space telescope. The researchers found that the amount of cloud cover fluctuated regularly, with particularly cloudy conditions in 2002 and 2015, and particularly clear ones in 2007 and 2020.

The dip in cloud cover in 2020 was the lowest ever observed – Neptune as a whole was the darkest we have ever seen it, without any white clouds to reflect sunlight. “Even now… the most recent images we took this past June still show the clouds haven’t returned to their former levels,” said Chavez in a statement. “Neptune’s previous period of low cloud activity was not nearly as dramatic and prolonged.”