Or you can go here:
Is there a definite answer? No, but there are multiple theories that make sense and add up to the reason the moon is here.
If you're talking about it "all" got here, as in the entire universe, no, we don't know, but there are theories about that as well, and none of them have magic attatched to it.
I don't know doesn't = magic. Which is why the whole audience is laughing.
Also, we do know how the tides got here which is one of the things bill was saying we don't know, we've known that for a very long time, and Bill asks why earth is the only planet with a moon, yet he is wrong about that as well, and is all explained very early in school.