Where Did The Earth Come From?

Recently, I was in New Zealand asking the real tough questions like: Where did the earth come from? Like, what was it before it was the earth? Like, how did it get here?

Those who were game to answer my question realized that an explosion was important to Earth's formation. I suppose it was created from space. I don't know what that explode in space is, and I suppose just heats of gas built up—bang—got planet. Same with the sun and everything else.

So you're saying it came out of some sort? I'd say it would have been gas. Yeah, it would have been an explosion. And then after that, there was just a planet there. Or, hmm, that's a really good question actually. I suppose it would be a whole bunch of guesses and then—bang—planet started revolving.

All the gases were right. Was there a particular explosion you had in mind? Perhaps one you learned about from a popular American sitcom, "The Big Bang"?

Yeah, "Big Bang." "Big Bang Theory" or something like that. It was a bunch of... for during the Big Bang. I've been to a couple of, um, museums here in New Zealand, and then it all starts with the Big Bang, it says. And then you see a lot of, um, volcanic action.

The Big Bang Theory—that's one of the theories of how Earth was created. So the Big Bang created the earth? Yes, like boom, and Earth was there.

Now, the trouble with explosions, which I was trying to hint at, is that they tend to blow stuff apart. They're more destined. What we're looking for is a mechanism to form the earth, to bring things together. So how could the earth form out of an explosion?

That would then cluster together and compact together and consolidate. It was debris that gathered together through gravity.

Okay, where did that debris come from?

Uh, the Big Bang, I suppose. Originally, that big explosion led to a bunch of debris. Then, now we're on the trip.

All mass is what causes matter to clump together into galaxies, stars, and planets. There's only one little problem. After the Big Bang, there were only two elements: hydrogen and helium in the whole universe. So how could we form the earth, including its oxygen, carbon, nitrogen, silicon, aluminum?

I say it that way for my Australian viewers. How could we form all these other elements? Well, the truth is the Big Bang didn't form the earth, at least not directly. The Big Bang formed galaxies of stars.

Let's focus in on one of these stars in particular, one whose contents will go on to form the earth. In this star, the lighter elements are fusing together to form heavier elements: carbon, nitrogen, oxygen, and eventually all the elements up to iron.

Now when this star runs out of nuclei to fuse, it explodes, and out of that debris could form either directly our solar system, or another star which then explodes and forms our solar system. So you could say the sun is a second or third generation star.

And you might say, well, that would have taken a very long time to occur, and it's true. The earth has been around for about 4.5 billion years, but the Big Bang happened 13.7 billion years ago.

So if my arm span represents the time that the earth has been here, then the Big Bang would be about here. You're doing a bang-up job, guys!

So when people tell you that we're all made of stardust, they're not trying to be metaphorical or poetic necessarily; they're being literal. The iron in your blood was actually formed in the core of a star at millions of degrees. We and the world around us can only exist because of the elements that were formed in earlier stars.