unusual images obtained on May 16,2016, by NASA's Hubble Space Telescope confirm the presence of a dark vortex in the atmosphere of Neptune. This full visible-light image shows that the dark feature resides near and below a patch of colorful clouds in the planet's southern hemisphere. Though similar features were seen during the Voyager 2 flyby of Neptune in 1989 and by the Hubble Space Telescope in 1994, or this vortex is the first one observed on Neptune in the 21st century.
Source: phys.org