The change in direction of this latest storm is not the only unusual thing.It also has obvious characteristics lack of Small, bright, feather-like clouds, usually seen above Neptune's black spot. According to scientists, when the black spots stopped moving south, the clouds disappeared. The bright clouds are composed of methane ice crystals, which form when the gas moves upward above the black spot and freezes into crystals.
The larger dark spot also has a smaller companion-called the "dark spot jr". – It was first discovered in January 2020, and astronomers thought it might have gotten rid of the major storm. This smaller point did eventually disappear. As Wong of the University of California, Berkeley said:
We are excited about these discoveries, because this smaller dark fragment may be part of the dark spot destruction process. This is a process that has never been observed. We have seen some other black spots disappear gradually, they disappear, but we have never seen any interference, even if the computer simulation has predicted it.
The new major storm started in the northern hemisphere of Neptune, and then began to drift southward to the southern hemisphere of the earth. From observation of other such storms, it can be seen that they are beginning to fall apart. But not this time. Instead, by August 2020, the storm has slowed and changed direction, moving north from the place where it occurred. This is the first time Hubble has noticed this behavior in 30 years.
Interestingly, the time when the smaller dark spots appeared and the larger storms reversed course and started to retreat. This newer point is about 3,900 miles (6,276 kilometers) wide and appears on the side of the larger point facing Neptune's equator. In this area, some computer simulations indicate that large disturbances may occur, but the timing does not seem to match. Huang said:
When I saw the small spots for the first time, I thought the large spots were disrupted. I don't think that another vortex will form because the small vortex is closer to the equator. So it is in this unstable area. But we cannot prove that the two are related. It is still a complete mystery.
Also in January  The dark vortex stopped moving and began to move north again. Maybe by removing the debris, it will be enough to prevent it from moving to the equator.
Neptune’s storms are similar to other natural gas giants and ice giants (Neptune is an ice giant), and can expand in size to make the largest hurricane or cyclone on the planet war. Unlike Earth hurricanes, they are high-pressure systems that form at mid-latitudes and then move closer to the equator. In the northern hemisphere, they rotate clockwise due to the Coriolis effect. However, as the storm approached the equator, this effect diminished and the storm eventually disintegrated.
As the Neptune storm develops and then finally ruptures, this is the common situation. But in this case, the storm did not completely enter the "killing zone" beyond the equator. As Huang said:
It's exciting to see this behavior as it should be, and then suddenly stop and go back. It's amazing.
Don’t know Jr. Also survived, but scientists are continuing to analyze the data provided by Hubble. These new discoveries also provide valuable clues to the overall behavior of Neptune's atmosphere.
Hubble has played a central role in observing these spots on Neptune, especially since no other spacecraft has visited the planet since Voyager 2. According to Amy Simon of NASA's Goddard Space Flight Center:
If it weren't for Hubble, we wouldn't know anything about these latest black spots. Now, we can track major storms for many years and observe their complete life cycle. If we don’t have a Hubble telescope, then we might think that the big dark spot that travelers saw in 1989 is still like a big red spot on a starfish, still on Neptune. Moreover, we don't know anything about the other four attractions that Hubble discovered.
Until the (hopefully) completion of the new mission, telescopes like Hubble will continue to observe the mysterious dark spot of Neptune.
Bottom line: A big dark storm on Neptune unexpectedly changed its direction and saved itself from the impending destruction. It may also have produced a smaller companion storm.
Source: Neptune's NDS-2018: The Dark Vortex That Will Not Die