25. Where did the water on Earth come from?
Have you ever thought about where our water comes from? The tap, might be the obvious answer, but what about before that? What about before all of that, before the oceans? When earth was forming, where did the water that covers so much of our planet, come from?
Our rich water reserves (both salty and fresh) have been around for a few billion years and for a long time, modern scientists have though it came from comets and asteroids – in other words, space. Or at least the hydrogen and oxygen molecules that make water did.
But they’ve long held the belief that there must’ve been other sources, because there’s simply so much of it. Now, they think that these molecules came from both rocky sources such as comets, as well as gaseous sources such as those found in the solar nebula, a cloud that formed after the formation of the sun.
How this might’ve happened involves a lot of complex astrophysics. But in a nutshell, it involved lots of water containing comets bombarding a very young earth when it was just hot magma and noble gases. At the same time, hydrogen and oxygen gases from the solar nebula were dissolved in this magma.
Fast forward a few billion years, and we dabble our toes in it, use it to make our coffee and shower in it. Far-fetched? You decide!