Porter is a large-scale impact crater in the Thaumasia quadrangle on the planet Mars, situated in Aonia Terra at 50.8° south and 113.9º west. The impact caused a bowl 105 kilometres (65 mi) across. The name was chosen in 1973 by the International Astronomical Union in honour of the US astronomer and explorer, Russell W. Porter (1871-1949).

Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually have a central peak. The peak is caused by a rebound of the crater floor following the impact.

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  Porter Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Gullies are visible in the upper left.
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  Gullies in Porter Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Note: this is an enlargement of the previous photo.

See also

• Climate of Mars
• Geology of Mars
• HiRISE
• List of craters on Mars
• Martian gullies
• Ore resources on Mars
• Planetary nomenclature
• Water on Mars