Last updated on April 24, 2014 at 5:30 EDT
Crater in Mare Humorum
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Crater in Mare Humorum

December 7, 2012
Why is this crater so bouldered? Bouldery craters are primarily the result of bolides impacting solid material. More cohesive materials produce larger boulders when they are impacted. Craters like these can give clues as to the thickness of the regolith. As craters increase in diameter, they excavate further into the surface. So if a crater has no boulders, it has probably excavated only regolith. This impact though has punched through the overlying regolith and fragmented the underlying mare basalt into large boulders. LROC context image of today's featured image, located in the white box. Image width is 100 km [NASA/GSFC/Arizona State University].