Where Did Earth's Water Come From?

↓↓↓ More info and sources below ↓↓↓

Why is Earth is a blue planet? Because it’s covered in water! Where did Earth’s water come from? Of course, water isn’t unique to our planet. The origin of water traces beyond the solar system to the earliest days of the universe. Here’s the story of the galaxy’s H2O.

Special thanks to:
David O’Brien, Planetary Science Institute
Wendy Panero, The Ohio State University
Karen Meech, Institute for Astronomy at the University of Hawaii
Shmuel Bialy, Tel Aviv University
Avi Loeb, Harvard University
Ilse Cleeves, Harvard-Smithsonian Center for Astrophysics

References:

Bialy, S., Sternberg, A., & Loeb, A. (2015). Water Formation During the Epoch of First Metal Enrichment. The Astrophysical Journal Letters, 804(2), L29.

Bradford, Charles M., et al. "The water vapor spectrum of APM 08279+ 5255: X-ray heating and infrared pumping over hundreds of parsecs." The Astrophysical Journal Letters 741.2 (2011): L37.

Cleeves, L. Ilsedore, et al. "The ancient heritage of water ice in the solar system." Science 345.6204 (2014): 1590-1593.

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[makdavian]

A nice watered down history of Earth I see.

[besmart]

This is why Earth is a pale blue dot in the cosmic sea…

Thanks for watching, sharing, and subscribing! Let us know what you thought of this week's video 💦🌎💦

[NewMessage]

Someone will start selling bottled 'Cosmic Water' any minute now.

[EvilHeadBoy]

I just wanted to say I loved the transition from the blurry image to the animation of the galaxy with a black hole. It paints the picture of reality and what we actually see really well!

[disgruntledwookie]

It's a shame you didn't bother to point out that H2O is the most abundant chemical compound in the universe after H2. I think that's the real, satisfying explanation. For those interested:

The primordial soup of the universe contained about 90% hydrogen (by number of atoms) and 10% helium. a hydrogen nucleus is literally just a proton, the most stable hadron, so it's easy enough to see why it would form in such large quantities within the first second of the universe. Eventually, (once the universe expanded and cooled enough to allow it) these protons would combine with electrons and form the first atoms, but I'm getting ahead of myself. I said there were about 10% helium nuclei, but where did they come from? It's not so easy to make helium, you need to subject protons to immense heat and pressure just to get started. These days, helium is only really produced in stars, in fact, hydrogen->helium burning is the primary source of energy for stars on the main sequence. But think about it, in the first few moments of the universe, everything was so hot and dense, it was in many ways just like the core of a star, except EVERYWHERE. It didn't have much time before things expanded and cooled beyond the conditions needed for fusion, but in that brief window, some of the protons stuck together (one of them becoming a neutron) to form deuterium, and some of that deuterium would stick to another deuterium and form helium nuclei (which are quite stable). There was also smaller trace amounts of lithium, and maybe some insignificant amounts of slightly heavier elements, but really it was hydrogen and helium (including hydrogen isotopes like deuterium). Nucleosynthesis is a complex quantum mechanical process and I can't begin to explain the why or how of these things in a youtube comment. So anyway, pretty soon after the big bang, the universe cools past the necessary temperature/pressure for continued fusion, and we enter the dark ages. The universe was filled with a hydrogen/helium soup, but the first stars had not yet ignited, the universe was dark (apart from the bright infrared heat glow and maybe the CMB if we're past recombination). As things continue to cool, many of the hydrogen atoms will find it energetically favourable to combine into molecular hydrogen (H2). Helium, on the other hand, is a noble gas and is not chemically reactive. And until the first stars begin to burn, nothing much happened for a while. But now fast forward, and the first stars are burning hydrogen into helium, and helium into carbon and oxygen through the alpha processes. As it happens, oxygen is the 3rd most abundant chemical element in the universe. Take a second to be amazed by that. Why should that be the case? So far it has been very logical. Hydrogen has atomic number 1, and is the first most abundant element. Helium has atomic number 2, and is the second most abundant. Shouldn't lithium be next? Well, as it happens, not all atoms are created equal. Some nuclei are just easier to make, there are energetically favourable pathways to produce carbon and oxygen (in general, even numbered elements are more common because you can make them by sticking helium nuclei together). Long story short, after the first stars burn and explode their guts, you end up with something we call a GMC - Giant Molecular Cloud. This is what it sounds like. A massive cloud of molecules. But this cloud is made out of mostly hydrogen, then helium, then oxygen (other important common elements are carbon, iron, and silicon - all key components of the Earth). Since helium isn't chemically reactive, the GMC is chemically dominated by hydrogen and oxygen, which naturally combines to form H2O. Which is why GMCs are so rich in water. The large amounts of silicon also readily react with the more abundant oxygen, forming all kinds of silicate minerals. The carbon also tends to react with the oxygen, locking much of it away in volatile carbon compounds like carbon monoxide and CO2. So now you have a huge cloud (could be lightyears across) filled with molecular hydrogen, non-reactive helium, water, oxygen, carbon monoxide/dioxide, silicates, iron, and random sh*t. More or less in that order. Even after going straight through a star, the cloud is still mostly hydrogen BY FAR. But the key point here is that the second most abundant chemical compound is WATER. The stuff is everywhere. We've been talking for a long time about "why is there so much water on Earth", and this is a valid question which is more related to planetary formation, but on cosmic scales, water is abundant :)

[brantwedel]

"stay curious [and stay thirsty my friends]"

[CuriosityGuy]

If gravity attracts, how could Jupiter's gravity have flung or repelled asteroids away from it towards the earth?

[JustinY.]

That's a lot of asteroids that must have hit earth for that much water to form.

[ZTS]

Multi-part question here: Wouldn’t an atmosphere be needed to hold the water (along with gravity) so the sun wouldn’t evaporate it all? If so, wouldn’t said atmosphere burn up many of these comets and asteroids that would have delivered frozen water up (or evaporate the frozen water, at least)? I may be thinking of this all wrong, but it seems like an atmosphere would be needed to help retain the water, yet it would have had to have been weaker so fewer would burn up or lose all water upon entry. Is such a balance possible considering our proximity to the sun? Either it would seem to be that the atmosphere was thinner and/or weaker, or those comets/asteroids must have been very large so as to not lose most of their “payload” before impact.

Also, on a slightly different note, are there still large comets/asteroids found in the Solar System carrying water today?

[mr.dr.genius]

1:08 What is this suposed to mean? (bottom left)

[matthewjohnvu]

This helps me get over the hurdle of alien life. I always say that our biggest problem with finding life on another planet is that their level of evolution may be at a very different (earlier) stage from ours.

[Mr_Case_Time]

It would be interesting to find exactly when most of it became salt water and why that happened.

[johnathonmcdonald]

Do a video on why do we stretch after sitting down

[fohhee]

I did the count, u said 39 times "water"

[frederickjohnpicarello]

What really surprises me is not that the Earth has water but but the insane amount of it on this planet. I just can't imagine the process that led to the amount of water that we currently have..

[magnuslindqvist]

I got sad when the video was ended. I's like "aww man, already?!"

[ChintanPandya]

Half way through your video, I poured up a cold glass of water, heard its sound, watched it fall from the bottle into the glass and curl up before bouncing and rising until the glass was 3/4 full. Watched the condensation on the outside trickle down. Water from the atmosphere around me now suddenly on the glass because the air around it cooled and could not hold enough moisture. Then, then i took a sip and took a breath. Dihydrogen monoxide. The liquid of life as we know it. Since at least 4.5 billion years.

[teddyscribner]

We can(or should) not be 100% sure about anything.

[Naiadryade]

Neat that this video came out so close in time to the Eons video about a time in Earth's history when that water was circulating a whole lot!

[illjan]

I have a question: Why does fire make light? Is it because of the heat, or why?