The Great Dark Spot (GDS) is an elliptically shaped region of Neptune roughly 8,100 miles wide and 4,100 miles high. Technically, it is a series of spots that generate and dissipate every few years, which differentiates them from Jupiter’s Great Red Spot, which has been singular and constant for hundreds of years.
However, as with Jupiter’s spot, Neptune’s spots are anticyclonic super storms, intense cyclones that produce 1,500 mph winds. These winds are the fastest to have been recorded in the Solar System and are believed to occur in the planet’s troposphere.
Currently, there is a new Great Dark Spot on Neptune in its northern hemisphere and, as such, has been termed the Northern Great Dark Spot (NGDS).