Why are there craters on the moon?

The moon does not have processes that can erase the evidence of past impacts like the Earth does. Erosion is what helps keep the Earth crater free, but the moon doesn’t have erosion because it has no atmosphere. Tectonics help the surface of the Earth recycle making the rocks on the moon much older. The moon has not experienced tectonics in billions of years, allowing the craters to form and remain. Once the moon has been hit, it has no power to protect itself, therefore craters stay.

The near side of the moon has a much thinner crust which allowed volcanoes to fill in ancient large craters. The near side also has dark seas, called maria, which are large flat areas of basalt. There are no features like this on the far side of the moon.

When the Mars-sized object that hit Earth and created the moon, both the moon and Earth were very hot. Since the moon is much smaller than the Earth, it cooled quickly. The Earth was still over 2500 degrees celsius and because the Earth and the moon are tidally locked, the heat of the Earth radiated towards the near side of the moon. The far side of the moon was able to cool down and therefore has a thicker crust. When meteoroids struck the far side of the moon, the crust was too thick, creating craters and highlands, but almost no maria.