Credit: NASA, ESA, Erandi Chavez (UC Berkeley), Imke de Pater (UC Berkeley), LASP Interactive Solar IRadiance Datacenter

This sequence of Hubble Space Telescope images chronicles the waxing and waning of the amount of cloud cover on Neptune. This nearly-30-year-long set of observations shows that the number of clouds grows increasingly following a peak in the solar cycle – where the Sun’s level of activity rhythmically rises and falls over an 11-year period.

The Sun’s level of ultraviolet radiation is plotted in the vertical axis. The 11-year cycle is plotted along the bottom from 1994 to 2022. The Hubble observations along the top, clearly show a correlation between cloud abundance and solar peak of activity.

The theory is that the increased ultraviolet radiation from the Sun, during its peak of activity, causes chemical changes deep in Neptune’s atmosphere. After a couple years this eventually percolates into the upper atmosphere to form clouds.

Provider: Space Telescope Science Institute

Image Source: https://hubblesite.org/contents/news-releases/2023/news-2023-019

Curator: STScI, Baltimore, MD, USA

Image Use Policy: http://stsci.edu/copyright/