What would need to happen for the moon to explode and the debris to start hitting Earth?
A lot of things would have to go wrong for the Moon to go boom.First off, stable rocky planets rarely just explode. Even violently active ones (like Earth or Io) aren’t going to just up and explode.Unless you’re Praxis - the moon of the Klingon homeworld. But, I like to think the Klingons were experimenting with some very *interesting* stuff when that happened.
If you want to be sure the Moon explodes, you’ll have to do one of two things.
You can hit it with another body approximately the same size of the Moon going pretty fast. That’ll make them both go boom, and the resulting rain of rocks is going to be really, really bad for Earth.Or, you can pump a large amount of energy into it by using explosives. Mind you, you’ll need a large amount of them to make the Moon really go boom - more than have ever been made in the history of Earth - or a huge amount of antimatter.
Antimatter is the evil, opposite of matter. When an atom of matter and and atom of antimatter collide, both atoms disappear into a flash of energy. Einstein’s equation E=mc^2 tells us how much energy a given amount of mass has.
So, how much would it take to blow up the Moon?Every solid body has what is knows as it’s gravitational binding energy. This is the amount of energy that must be added to a body for it to fly apart and not pull itself back together. It’s how much energy you need to make it explode completely.
For the Moon, that’s 1.2 x 10^29 joules. Or, in other words, 29,000,000,000,000 megatons. You can get that much energy out of about 1,300,000,000 tons of antimatter. If it was an antimatter asteroid, that would be a rock about 1 km in diameter. Smash that antimatter rock into the Moon, and boom!
Result - no Moon, and a very very ripped up Earth full of dead things.
tl;dr - You can’t explode the Moon without killing every living thing on Earth.
