Crater Alphonsus

This oblique photo shows the crater Alphonsus on the eastern edge of Mare Nubium. Note the five dark patches along the crater floor edge. Each of these patches has a central pit. Three are located along clear fracture trends. Also, most of these pits are also elongated or irregular in shape. Thus, they are unlikely to be small impact craters. Instead, they probably mark the sites of small vulcanian eruptions. Note: The long corkscrew-like pole pointing into the image from the left is part of the Apollo Orbiter. (Apollo 16 image M-2478, looking southwards.)

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