Three billion miles away on the farthest known major planet in our solar system, an ominous, dark storm â€“ once big enough to stretch across the Atlantic Ocean from Boston to Portugal â€“ is shrinking out of existence as seen in pictures of Neptune taken by NASAâ€™s Hubble Space Telescope.
Immense dark storms on Neptune were first discovered in the late 1980s by NASAâ€™s Voyager 2 spacecraft. Since then, only Hubble has had the sharpness in blue light to track these elusive features that have played a game of 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 Jupiterâ€™s Great Red Spot (GRS), the storm swirls in an anti-cyclonic direction and is dredging up material from deep inside the ice giant planetâ€™s atmosphere. The elusive feature gives astronomers a unique opportunity to study Neptuneâ€™s deep winds, which canâ€™t be directly measured.