The mysterious storm on Neptune shrinking away out of existence, images captured by Hubble Space Telescope reveals.
The storm, which was first discovered in 1980s, is thought to have been as big as the Atlantic Ocean stretching from Boston to Portugal. However, Hubble observations reveal that this massive storm has been shrinking over the years and is almost out of existence. After its initial discovery, the storm has been playing peek-a-boo over the years.
Hubble found two dark storms that appeared in the mid-1990s and then vanished. This latest storm was first seen in 2015, but is now shrinking.
Like Jupiter’s Great Red Spot (GRS), the storm swirls in an anti-cyclonic direction and is dredging up material from deep inside the ice giant planet’s atmosphere. Unlike Jupiter’s GRS, which has been visible for at least 200 years, Neptune’s dark vortices only last a few years. This is the first one that actually has been photographed as it is dying.
The elusive feature gives astronomers a unique opportunity to study Neptune’s deep winds, which can’t be directly measured. The dark spot material may be hydrogen sulfide, with the pungent smell of rotten eggs.
According to researchers the dark vortex is behaving differently from what planet-watchers predicted. The vortex seems to be dying, scientists say, and contrary to belief, the dark spot has apparently faded away rather than going out with a bang.
The first images of the dark vortex are from the Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of our solar system’s four outer planets. Only Hubble has the unique capability to probe these worlds in ultraviolet light, which yields important information not available to other present-day telescopes.