These images of Mars show the two polar ice caps. The northern ice cap can be seen in the left image, which was taken by the Hubble Space Telescope in March 1997. The southern ice cap is visible in the right image, which was captured by Hubble in August 2003.
Images courtesy Phil James (Univ. Toledo), Todd Clancy (Space Science Inst., Boulder, CO), Steve Lee (Univ. Colorado), and NASA [North Pole image]; and NASA, J. Bell (Cornell U.) and M. Wolff (SSI) [South Pole image].