NASA does a lot of work with a little money. They send rovers to Mars, they launch satellites into space, they observer distant stars and galaxies and they look at the moon. We often forget about them moon perhaps because of its ubiquitousness in the sky. That is until NASA informs us that they have recorded the largest explosion ever recorded on the moon. If you happened to be looking at the moon at the time of impact, you would have been able to see it with the naked eye. No telescope required. 40 kilograms at 90,000 kilometers per hour. KER-SPLAT!
Even a casual observer will notice that the moon gets hit a lot. It’s surface is more cratered than a teenager’s face with acne. With no atmosphere, the moon takes the full force of any impact from rogue meteoroids. Any colonization that we do on the moon would almost certainly be required to be underground as a result.
Earth, on the other hand, has a nice atmosphere of various gases that not only allows us to breath and live, but also protects us from the potentially deadly flying rocks that are strewn across our solar floating in mathematically precise orbits around the Sun just like Earth. Any of those rocks that try hitting the Earth are met by billions of molecules joyously bouncing off of each other but mostly spread impossibly far apart. The plunging rock changes this dynamic. It pushes those molecules closer and closer together where they start bouncing off of each other more and more frequently. All of this bouncing around causes pressure and temperature to rise quickly. The higher pressure and temperature start picking away at the death spiraling rock until it breaks apart into fine dust and tiny pebbles that fall harmlessly to Earth. Well, most of the time.
So, thank you atmosphere! Your praises cannot be sung enough. Ballads should be written and stories told of all of your invisible, silent, never ending works.