The dark , elliptically-shaped spot ( with initial dimensions of 13,000 Ã -- 6,600 km , or 8,100 Ã -- 4,100 mi ) was about the same size as Earth , and was similar looking to Jupiter 's Great Red Spot . The dark , elliptically-shaped spot ( with initial dimensions of 13,000 Ã -- 6,600 km , or 8,100 Ã -- 4,100 mi ) was about the same size as Earth , and was similar in general appearance to Jupiter 's Great Red Spot .