Craters on the Earth side of the Moon

[ZiraldoAerospace]

How is it that there are impact craters on the side of the Moon that faces the Earth? Is is from stuff flying in between the Earth and the Moon and hitting it at an oblique angle? Wouldn't that make the craters look weird? Am I missing something completely stupid and/or obvious? Please help!

 

[MeteorWayne]

How is it that there are impact craters on the side of the Moon that faces the Earth? Is is from stuff flying in between the Earth and the Moon and hitting it at an oblique angle? Wouldn't that make the craters look weird? Am I missing something completely stupid and/or obvious? Please help!

First, for much of it's history, the moon was not locked to face the same time to the earth. This was particularly true during the Great Bombardment ~ 1 billion years after the solar system formed when the majority of the larger craters in the solar system were created.

Second, craters surprisingly come out nearly round except at very extreme impact angles, less than 10 or 15 degrees.

Finally, the earth actually blocks a very small part of the sky as seen from the moon. Try it 3D style like I do in the lectures I give.

Take a 3" ball (maybe an orange?). That's the earth. The moon is then 5/8 inch in diameter and is 7 1/2 feet away.
If you see it in 3d, it's clear that the sky is a pretty clear view from the lunar surface. (Think of how much of the sky is blocked in the famous "earthrise" picture from the moon...it's not really much )

Finally, because of the earth's gravity, it actually is a gravitational lens (albeit a weak one) and bends the path of asteroids that would miss the moon to hit it.

Wayne

 

[ZiraldoAerospace]

Wow, great answer, thank you very much! I didn't think about how small of an amount of the Moon's sky the Earth takes up. Also, the impact angle thing was interesting. Thanks again.

 

[MeteorWayne]

Glad to help, it was fun to answer! :geek:

 

[drwayne]

I definitely took notes on that answer sir.

 

[kendallfrost]

All you need is a computer with a sound card, and speakers or
headphones. The rest is depends on your skills and the software you
are using.

 

[MeteorWayne]

Huh? What does this have to do with Craters on the earth side of the moon?