Neptune has seasons which drive some of the features in its atmosphere, but those seasons are much longer than on Earth, lasting for decades rather than months.
This new Hubble view of Neptune shows a dark storm near the top center of the planet’s disc in the region currently experiencing “summer.” The feature is the fourth and latest dark vortex captured by Hubble since 1993. Two other dark storms were discovered by the Voyager 2 spacecraft in 1989 as it flew by the remote planet. Since the Voyager flyby, Hubble has been out only telescope with sufficient sensitivity in blue light to track such elusive features which have appeared and faded quickly.
Image Credit: NASA / STScI
This new Hubble Space Telescope image reveals a new dark vortex in the atmosphere of Neptune. Neptune’s dark vortices are high-pressure systems and are usually accompanied by bright “companion clouds,” and the visible-light image on the left shows the dark feature near a patch of bright clouds in the planet’s southern hemisphere. The bright clouds form when the flow of the atmosphere is perturbed and diverted upward over the dark vortex, probably causing methane to freeze into ice crystals. The image at top right is a full-color close-up of the complex feature. The image at bottom right shows that the vortex as seen in blue wavelengths.
Image Credit: NASA
This movie was put together using 70 days worth of solar system observations from the Kepler spacecraft taken during its reinvented “K2” mission. The planet Neptune appears from the left on Day 15, followed by its moon Triton, which looks small and faint. Sharp-eyed observers may also spot Neptune’s tiny moon Nereid at Day 24.
Neptune doesn’t actually move backward in its orbit, but it appears to do so because of the changing position of the Kepler spacecraft as it orbits around the sun. The same sort of retrograde motion is seen in the movement of the outer planets over the course of a year as viewed from Earth.
Video Credit: NASA