" which tells us (among other things) about how Clair Patterson determined the age of the Earth. The episode explains Patterson used meteorite fragments, such as those from the Canyon Diablo crater, because they were assumed to be leftovers from the creation of the solar system. My question is one of clarification; specifically, how they could be sure that assumption was correct?
I've tried doing some reading on this before coming here and while it's answered my question in part, I'm still not clear on one crucial part of this.
As the Wikipedia entry for the episode says
, "... scientists have used the debris from meteor impacts, such as the Meteor Crater in Arizona, knowing that the material from such meteors coming from the asteroid belt would have been made at the same time as the Earth."
That's fine; I completely understand that the asteroid belt is basically the leftovers from the formation of our solar system. But I think I either missed the part of the episode (or they didn't explain it very well) that said how we, and indeed Patterson, knew the Arizona Meteor Crater was a meteorite from the asteroid belt? How can we be sure it didn't come from outside our solar system before eventually landing on Earth?
It doesn't help that most of the stuff I've read on Patterson's work keeps using the words "assume" and "assumption" about the nature of meteorites. To me, who doesn't know any better, that seems like a big assumption to make.
To be clear, I'm not here to dispute Patterson's findings or the age of the Earth. I'm quite certain people far smarter than me are right when they say the Earth is around 4.5 billion years old. I almost have a clear picture of how he worked it out. I just need someone to explain to me (as simply as possible, please) how we know the meteor he used came from the asteroid belt and not from somewhere outside our solar system?