Introducing
The moon's surface is covered with craters, ridges, mountains and valleys. The dark Maria are the smoothest part because the lava that created them flowed over and covered old craters. These are some facts about the moon's surface:
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The biggest moon crater that can be seen from earth is called bailly. It about 290 km across. The largest moon crater is on the far side of the moon and so cannot be seen from earth.
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Because the moon has no air or water to wear rocks away, the moon surface has remained unchanged for thousands of millions of years.