Eli5, why does earth have way less craters then almost any other planet in our solar system?
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Naturally-occurring craters are typically caused by debris from space that survives to impact the surface of a planet.
Planets with an atmosphere will have fewer craters because debris burns up before it can reach the surface.
Fast moving debris entering Earth’s atmosphere must withstand intense heat caused by friction with the air.
Most or all of the debris burns away before it can reach the planet and make a crater.
We have water and weather and plant life. That erases the craters we get much faster than they get erased on other planets.
Two reasons.
First, we have a very large moon. The moon intercepts a lot of asteroids for us. Either taking the hit for us, or pulling the asteroid away with it’s gravity.
Second, we have weather. When an asteroid hits the moon, that crater stays there essentially forever. When as asteroid hits the earth, that crater is worn away over time by wind, water, and animals.
Isnt there something about Jupiters gravitational pull that throws a lot of debris off course that would have otherwise hit earth?
Erosion and plate tectonics are both systems that slowly erase craters over time.
Earth has very very very active erosion processes and plate tectonics compared to the other crater-filled rocky planets and moons we see in our solar system.
Active surface which is constantly “recycling” the surface plus a thick atmosphere which slows down and destroys many objects.
Earth has a much thicker atmosphere than Mercury or the Moon (or Mars) so objects coming close have to deal with more friction when entering our atmosphere than these others’, meaning more of them burn up – either they burn up entirely or partially, meaning a smaller impact object and a smaller crater as a result.
Earth’s surface is also about 70% water so a majority of objects will impact over the oceans so we wouldn’t be able to see the craters anyway (plus the water resistance will slow them down, again reducing the size of any craters).
Earth is also a very geologically active planet; the crust is divided into different tectonic plates which move against one another (causing earthquakes and boundaries where they meet – hence the ring of fire around the Pacific Plate). Over time a lot of the crust gets ‘recycled’ due to this movement of plates so some of the older craters will disappear.
Earth has an atmosphere to prevent most meteors and comets from surviving reentry, as well as lots of water and weather in general to erode the craters into nothing over long periods of time.
Because weather and plate tectonics. The thick atmosphere causes surface erosion which fills in craters and plate tectonics keeps making new crust replacing the older pitted crust.
We have lots of water to erode old craters.
We also have a relatively thick atmosphere to stop meteors and a fairly large moon to deflect asteroids.
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