Mars

Article By:

Beatty, J. Kelly Senior Editor, "Sky and Telescope Magazine," Cambridge, Massachusetts.

Last reviewed:February 2022

DOI:https://doi.org/10.1036/1097-8542.407700

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• Mars, published January 2021:Download PDF Get Adobe Acrobat Reader
• Mars, published March 2019:Download PDF Get Adobe Acrobat Reader
• Mars, published July 2018:Download PDF Get Adobe Acrobat Reader
• Mars, published October 2014:Download PDF Get Adobe Acrobat Reader

The planet fourth outward from the Sun and the planet most like Earth in terms of geology, climate, and suitability for life. Mars is nicknamed the "Red Planet" for its reddish hue (Fig. 1). Besides Earth, Mars is the most-studied world in the solar system. Numerous interplanetary spacecraft have visited Mars, while new stationary probes and rovers continue to be sent to further explore its surface. Although Mars is cold, dry, and inhospitable in present day and likely was so stretching back for most of its 4.5-billion-year history, ample evidence exists that during its first billion years, Mars might have hosted a warm climate along with significant bodies of water on its surface. These findings have established Mars as one of the likeliest places besides Earth in the solar system to have developed life, a prospect that has driven the exploration of the Red Planet from orbit and through a continuing series of lander and rover missions. For a set of basic planetary and orbital characteristics of Mars, see Table 1. See also: Astrobiology; Earth; Planet; Solar system

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