Why does the moon have so many craters when Earth doesn’t have, even though Earth’s gravity is stronger and it should be the one attracting the comets?
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The moon doesn’t have an atmosphere or oceans, so there’s nothing to smooth and erode things. No plate tectonics either.
Earth has tectonic activity, plus weather erosion, which wipes out traces of impacts over time.
The moon is basically a crypt which stays as is until something impacts it.
If you remove all the waters on Earth you will understand that we are not that far from the Moon’s appearance.
Meteor Crater in Arizona is one of the best viewed and studied
https://www.britannica.com/place/Meteor-Crater
The first and second bombardment periods of the primordial solar system were billions of years ago. Plate tectonics has cleaned up our surface. Also- having a magnetosphere (from our molten rotating planet core) protects the atmosphere which toasts incoming debris.
Moon lacks atmosphere, magnetosphere, and plate tectonics. It’s scars today are… primarily from the second bombardment period (I think) from forever ago.
Meteoritic activity at this point is down to small things that get burned up in our atmosphere. It’s been billions of years, most big things have orbited enough times that their orbitals are fairly clear of major debris.
That said, we consistently get two meteor showers every year- they are a lot of fun to watch without light pollution.
The last and perhaps most significant thing at this point is that Earth’s gravity is meagre compared to Jupiter, the Sun, and other gas giants. Anything big hardly cares about little old us.
Last last thing— Comets typically don’t cause impact craters on planets with atmospheres. They are typically made of mostly of ice. I think they hit triple point on entry and make a big sonic booming noise— you can google a video of one impacting Russia. Meteors are typically a terrestrial composition. Those of notable size are apocalyptic if they hit…. Though I suppose a comet of sufficient mass would be a big problem too!
Geology and biology. The moon is not geologically active, is devoid of life, and has very little atmosphere; the Earth is extremely opposite. We have volcanoes, plate tectonics, erosion, life.
The Earth has been bombarded every bit if not more than the Moon, but there are no processes to cover up the tracks, so to speak.
Definitely not a direct answer to your question, but it is partially answered in “Astrophysics For People In A Hurry” by Neil deGrasse Tyson.
Audiobook voiced by Tyson is less than 4 hours.
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