This image shows the northern polar ice cap on Mars. White areas are primarily water ice that exists throughout the year. Light brown areas near the ice are the "polar layered terrain", a mix of layers of ice and dust. A darker brown band of dune fields surrounds the polar cap. A huge canyon, Chasma Boreale, slices through the ice cap - from upper left towards lower right, starting at the 10 o'clock position, in this image. The northern ice cap is about 1,100 km (680 miles) across. This image, captured by the Mars Global Surveyor orbiter in March 1999, shows the North Pole during the Martian summer season.
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Image courtesy of NASA/JPL/ Malin Space Science Systems.

The North Polar Regions of Mars

The North Pole of Mars has a large ice cap on it. The ice cap is mostly made of water ice. In the winter, carbon dioxide from the atmosphere freezes and deposits a layer of dry ice (frozen CO2) on top of the ice cap and the surrounding terrain. The polar cap grows much larger in area in the winter because of this. When summer returns, warm temperatures cause the dry ice to sublimate away, and the polar cap shrinks in size.

The northern ice cap is about 1,100 km (680 miles) across. It has a huge canyon, called Chasma Boreale, slicing through it. The edge of the ice cap is surrounded by "polar layered terrain", a series of layers of ice and dust. The ground throughout the polar regions appears to have lots of ice in or under the soil, like permafrost on Earth. Winds caused by temperature differences between the ice cap and its surrounding blow throughout the polar regions. They carve interesting grooves into the ice cap, and build up sand dunes in areas around the pole.

In May 2008, a NASA spacecraft called the Phoenix Mars Lander will land near the North Pole on Mars. Phoenix will dig into the Martian soil, searching for water ice.

Just as you might expect, the two poles of Mars are the coldest places on the planet. Wintertime temperatures dip down to a frigid -150 C (about -238 F). The South Pole of Mars also has an ice cap.

Last modified May 23, 2008 by Randy Russell.

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