Denning (Martian crater)

Denning Crater
Quadrangle map of Sinus Sabaeus labeled with major features. Colored rectangles represent image footprints of Mars Global Surveyor.
Planet	Mars
Coordinates	17°42′S 326°36′W / 17.7°S 326.6°W / -17.7; -326.6Coordinates: 17°42′S 326°36′W / 17.7°S 326.6°W / -17.7; -326.6
Diameter	165 km
Eponym	William F. Denning, a British astronomer (1848-1931)

Denning Crater is a crater in the Sinus Sabaeus quadrangle of Mars at 17.7° south latitude and 326.6° west longitude. It is about 165 km in diameter and was named after William F. Denning, a British astronomer (1848–1931).^[1]

Craters

When a comet or asteroid collides at a high rate of speed interplanetary with the surface of Mars it creates a primary impact crater. The primary impact may also eject significant numbers of rocks which eventually fall back to make secondary craters.^[2] The secondary craters may be in clusters. All of the craters in the cluster would appear to be equally eroded; hence they would all seem to be of the same age. If these secondary craters formed from a single, large, nearby impact, then they would have formed at roughly the same instant in time. The image below of Dennin Crater shows a cluster of secondary craters.

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  Recent small crater on floor of Dennin Crater, as seen by HiRISE. Arrow shows group of secondary craters from ejecta falling down.

References

1. ^ "Planetary Names: Welcome". Planetarynames.wr.usgs.gov. http://planetarynames.wr.usgs.gov. Retrieved 2011-08-07. 
2. ^ "HiRISE | Science Themes: Impact Processes". Hirise.lpl.arizona.edu. http://hirise.lpl.arizona.edu/science_themes/impact.php. Retrieved 2011-08-07.