At the time this was the most detailed picture of Neptune we had.
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This picture was taken by Voyager 2. This image was taken from about 16 million kilometers away. You can see many interesting features on this picture. In the center is something called the “Great dark spot”. Along the longest dimension, it is as large as Earth. The white clouds in the picture are higher than the great dark spot. The white cloud near the bottom is called “scooter”, because it rotates faster than the Great Dark Spot, gaining about 30 degrees a rotation.[1]
After this picture was taken more efforts went into identifying the Great Dark Spot. Further research showed that it was a massive storm. The winds hit up to 1500 Miles Per Hour, the fastest wind ever recorded in the solar system. Later when hubble looked at it there was another spot in a different place, so they seem to be common. [2]