As with Mars (and Silo) we need a very deep pit to protect humans from the radiation.

> a whopping 728 feet across, more than twice the length of an American football field

For the rest of the world, this is ~222 meters, more than twice the length of a 100 meter track.

EDIT: Ninja'd! :-)

Archive: https://archive.ph/88rlJ

In some more enlightened timeline there's a spirited competition between institutional and amateur astronomers towards predicting these, and some amateur is sitting on a $10M this-person-told-us-so-and-we-bet-against-them prize, which gets bigger every year (no prizes for the institutional side, they get a salary).

In that timeline's future we're then competing over who can most reliably prevent them.

The winners of such frivolous competitions over protecting the moon get funding for the more serious job of protecting Earth.