The dark, elliptically-shaped spot (with initial dimensions of 13,000 × 6,600 km, or 8,100 × 4,100 mi) was about the same size as Earth, and was similar looking to Jupiter's Great Red Spot. Around the Great Dark Spot, winds were measured blowing up to 2,400 kilometers (1,500 miles) an hour, the fastest in the Solar System. The Great Dark Spot is thought to be a hole in the methane cloud deck of Neptune. The spot was seen at different times with different sizes and shapes. 