Scientists have long wondered why Mars’ southern polar cap is offset from its geographical south pole. Now they’ve solved the mystery. Two different localized climates are to blame, and they can in turn be blamed on two impact craters. Weather generated by the two regional climates creates conditions that cause the southern polar ice to freeze out into a cap whose center lies about 93 miles (150 kilometers) from the actual south pole. “Mars’ permanent south polar cap is offset from its geographic south pole, which was a mystery going back to the first telescopic observations of Mars,” says Anthony Colaprete, a space scientist from NASA Ames Research Center. “We found that the offset is a result of two martian regional climates, which are on either side of the south pole.”