Figure 3: NASA moon rock 14310. This rock was found partially buried on the moon's surface where it had lain since being broken off a larger rock. The surfaces that were buried are angular and unmarked. The exposed surface, in contrast, is covered with many small pits that were made by small space dust particles striking at speeds up to 10 kilometers per second (11,000 miles per hour). This slow process, which has rounded the exposed surface, accounts for nearly all lunar erosion. The rock is about 19 centimeters (71/2 inches) wide.
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