Exploratour - The Surface of Mars
Polar Caps
This is an image showing ice on the Martian south pole. This huge island of ice is called a polar cap. The north pole also has an ice cap. These ice caps resemble the north pole of the Earth. There is no known continent underneath the ice.
Besides ice, the southern polar region of Mars contains other interesting geologic features such as layered terrain and giant sand dunes. This image shows river systems and layered terrain.
The winter poles are the coldest regions of Mars. They can be in the dark for as long as 11 months. But the polar caps of Mars grow and shrink with the season, and sometimes completely disappear. This is because, unlike the ice of Earth, the polar ice of Mars is a mixture of water and carbon dioxide (dry ice). Carbon dioxide evaporates very fast as the temperature warms up with approaching spring.
The presence of the polar caps, and their changes with the seasons, provides evidence of water on Mars.