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This Mars image taken by the Mars Global Surveyor, released by NASA 17 September 1999, shows an area 500miles by 90 miles (800km by 300km) deep within the boundary of the seasonal polar frost cap of Mars. The image was taken in the early spring when sunlight has begun to shine on the region for the first time in many months, including the bright region at Left known as the "Mountains of Mitchel". This feature was named for astronomer Ormsby McKnight Mitchel who discovered it while observing Mars through telescope in 1846. Mitchel noted that the area is typically "left behind" as a bright peninsula when the rest of the polar cap recedes past this area in the spring because the frost tends to be more protected from the sunlight. (KEYSTONE/- PHOTO/AFP/NASA)