EARTH’S MOON I’ve seen other examples of Earth look-alikes. As a kid, I wondered why Earth’s moon has so many dents. Now, I know why. Every dent shows


where a space rock suddenly slammed into the moon. Bam! Rocks shatter. Some even melt. A huge dent, called a crater, forms.


Smash Hits Craters don’t cover Earth. T ere’s a reason why. Many space rocks never hit the ground. T ey burn up quickly when they enter Earth’s atmosphere. Sometimes, space rocks do strike


Earth. T en they make craters here. Unlike on the moon, though, these craters don’t last forever. Wind and rain pound the crater. T is pounding slowly break rocks


into smaller pieces. T is process is called weathering. T en wind, water, and gravity carry the pieces away. T is process is called erosion. T e moon has no atmosphere. So


weathering and erosion don’t happen there. When a meteorite hits the moon, it forms a crater which may last a long time. More meteorites crash down, too. Today, as many as half a billion craters cover the moon.


14 NATIONAL GEOGRAPHIC EXPLORER


Space rocks suddenly formed these craters on Earth’s moon.


Over time, water filled part of this ancient crater on Earth.


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