Changes

Recent satellite imagery has shown that Mars has a 3 kilometre deep ice cap around its polar regions. The northern polar region is surrounded by [[dune]] fields. During the Martian winter, a layer of carbon dioxide condenses at the poles and sublimates in the summer, leaving the water-ice and dust polar caps exposed. The ratio of dust to water-ice contained in the polar caps remains unknown.  

Recent satellite imagery has shown that Mars has a 3 kilometre deep ice cap around its polar regions. The northern polar region is surrounded by [[dune]] fields. During the Martian winter, a layer of carbon dioxide condenses at the poles and sublimates in the summer, leaving the water-ice and dust polar caps exposed. The ratio of dust to water-ice contained in the polar caps remains unknown.  

[[Image:F035a72_processed.jpg|thumb|100px|left|Cydonia Mensae, home of the alleged "face on Mars."]]

[[Image:F035a72_processed.jpg|thumb|100px|left|Cydonia Mensae, home of the alleged "face on Mars."]]

Persistent rumors tell of a "face on Mars," allegedly located in the Cydonia Mensae region at coordinates 40.9°N and 9.45°W. This alleged "face" is located in the midst of several pyramids and other mountains. Prevailing opinion at NASA is that the "face" is a trick of the eye due to the unusual lighting conditions.<ref name=faq>Williams, David R. "[http://nssdc.gsfc.nasa.gov/planetary/planetaryfaq.html#Mars Frequently Asked Questions - Planetary - Mars]." National Space Science Data Center, [[National Aeronautics and Space Administration|NASA]], January 2, 2008. Accessed May 27, 2008.</ref>

Persistent rumors tell of a "face on Mars," allegedly located in the Cydonia Mensae region at coordinates 40.9°N and 9.45°W. This alleged "face" is located in the midst of several pyramids and other mountains. Prevailing opinion at NASA is that the "face" is a [[pareidolia|trick of the eye]] due to the unusual lighting conditions.<ref name=faq>Williams, David R. "[http://nssdc.gsfc.nasa.gov/planetary/planetaryfaq.html#Mars Frequently Asked Questions - Planetary - Mars]." National Space Science Data Center, [[National Aeronautics and Space Administration|NASA]], January 2, 2008. Accessed May 27, 2008.</ref>

=== Water on Mars ===

=== Water on Mars ===