Interesting Moon article

Solving the Puzzle of Apollo 12′s Mysterious Magnetic Moon Rocks

In this article they talk of “this huge, whopping crater that’s roughly half the size of the U.S,” that is theorized to have struck the moon 4.5 billion years ago.
I'm no goephyicist, but something that can create a creater of that size sounds like a planet killer, large enough to knock the moon into deep space or destroy it completely.

http://www.universetoday.com/94210/solving-the-puzzle-of-apollo-12s-mysterious-magnetic-moon-rocks/