Residual south polar cap

Residual south polar cap

. In winter the southern polar cap is covered with extensive deposits of solid carbon-dioxide frost. In the southern summer, the cap shrinks to its minimum size shown here, about 400 kilometers across. Even though it is summer, the south polar cap remains cold enough that the residual polar frost consists of frozen carbon dioxide, or dry ice. The polar deposits lie on top of sediments that have been carved by wind into a spiral shape. This image was taken from the Mars Global Surveyor on 17 April 2000. (Courtesy of NASA, JPL and Malin Space Science Systems.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University