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amitym t1_j20060l wrote

Reply to comment by Austiniuliano in Earth was brought to life by ancient water-rich asteroids from the outer Solar System by marketrent

I'm sure there are dumb questions in the world but yours was not one of them!

It's not always obvious where this stuff goes, or how things work on other planets. We just recently learned about a whole new kind of natural chemical process when we saw it happening on Venus... until then no one knew that that particular kind of geochemistry was possible. (I forget the details but it was somewhere on this subreddit a while back.)

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Grinch83 t1_j22uybg wrote

Okay, I’ll try to throw one of the dumb questions of the world at you…

It’s easy enough to wrap my head around the idea that “x” wasn’t here before, but then a giant rock hurled from space crashed into the planet and brought it here.

But how did we get so much water from this asteroid(s)? In other words, how did we go from a relative puddle of water from the asteroid impact…to 72% of the earth’s surface covered in water?

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amitym t1_j22yha5 wrote

Haha still not dumb. So many people wonder about stuff like that, someone made a graphic. Here's a great way to visualize the answer:

https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/thumbnails/image/all-the-worlds-water.jpg

Basically... it's less water than you think. Because water, being water, tends to spread out flat. And the Earth is actually pretty smooth.

We think of all these tall mountains and deep chasms and stuff but they're only tall and deep from our human-scale perspective. From the perspective of the whole volume of the Earth, they are the teensiest aberrations. The depths are barely deep enough to get wet.

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Grinch83 t1_j230qan wrote

Ahhh, ok ok. Reading your response, I actually do remember hearing Neil deGrasse Tyson saying something along the lines of “if you could hold earth in your hand, at scale, it would feel & appear as smooth as a billiard ball.”

So operating under the assumption that this water asteroid hypothesis is correct, can we also safely assume the asteroid was roughly the size of the largest sphere in the graphic you provided? And all of the water currently on earth came from this event?

Even with your great response and visualization aid, it’s still mind bending to think about! (And that’s not even going into the odds of such an asteroid, making impact with such a planet…and a few billion years later, two descendants of this event discussing it over the internet.)

Awesome stuff; thank you for taking the time to respond! Totally understand if you don’t want to get too deep into the weeds with me here, so no worries on answering the above. But if you have other reading material for me, I’d love it if you could pass it along. I’m super intrigued. :)

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