it is thougt to be a hole in the methane cloud
It is the Great Red Spot. The Great Dark Spot was a storm on Neptune while Pluto has an elgonated orbit.
The Great Dark Spot on Neptune is a massive storm system, similar to Jupiter's Great Red Spot, that was observed in the atmosphere of Neptune. It is an atmospheric feature characterized by its dark appearance and is thought to be a large cyclonic storm. The Great Dark Spot was first observed by the Voyager 2 spacecraft in 1989.
The Great Red Spot is an anticyclonic storm raging on the surface of Jupiter. It has been raging for hundreds of years. The Great Dark Spot was a similar storm on Neptune. However is has now disappeared and smaller spots are regularly sighted in the atmosphere.
Neptune has a massive anti-cyclonic storm system spanning 13,000 x 6,600 km It is called "The Great Dark Spot". There is also a smaller cyclonic storm in the southern region, called, not surprisingly, "The Small Dark Spot"
The "Great Red Spot" that you are referring to is actually on Jupiter. The red spot is a violent storm that has been raging for at least 400 years. Neptune is known to show Great Dark Spots, which are very similar to the great red spot on Jupiter. However, these storms tend to only last a few years.