Why does Earth have fewer craters than the Moon?
Earth has been hit just as often, but wind, rain, rivers, plants and moving continents slowly wipe craters away. The Moon has no weather, so its craters last for billions of years.
Look at the Moon through binoculars and you will see craters everywhere. Earth is a bigger target, so it has been hit by even more space rocks. So where are all our craters?
The answer is that Earth keeps tidying itself up. Wind and rain wear down crater walls. Rivers carry away sand and mud and fill in hollows. Plants grow over them and soil forms on top. Oceans cover more than two-thirds of the planet and hide many craters. Over millions of years, the slow movement of Earth's crust, called plate tectonics, pushes old sea floor deep inside the planet and builds new mountains, destroying old craters altogether.
The Moon has no air, no rain, no rivers, no plants and no moving plates. So once a crater forms, it stays there almost unchanged, except when another crater forms on top. Some of the Moon's craters are more than 4 billion years old.
Earth still has about 200 known impact craters. Some, like Meteor Crater in Arizona, are young and easy to see. Others are so old and worn that geologists can only find them by studying special shocked rocks. Earth is like a scribble board that is wiped clean, while the Moon keeps every mark.