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Hellbent

How did Earth get wet?

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I am watching a Nat'l Geographic program on how the Earth got its water. The show proposes that it may have gotten it by comets smashing into the Earth over billions of years, and that the planet formed bone dry. They said one way to test the hypothesis was to compare the hydrogen of water on Earth (which all has the same ratio of heavy Hydrogen atoms to light ones) to the ratio of those atoms in ice in comets. They sampled Halley's comet and the results were that the water's ratio of hydrogen atoms were twice as heavy as that of those on Earth.

They then discovered really old rocks on Earth. 4.38 billion years old (which is just slightly younger than the Earth 4.5 billion years). If I understood it right, these ancient Zircon grains locked water in them in a unique chemical way. So they concluded that water was there at the beginning. But how? One scientist hypothesized that when the solar system was forming, dust, helium, hydrogen, oxygen were colliding, and water was forming between the collisions of hydrogen and oxygen. This free water doesn't just disappear if it is heated to evaporation. (Where would it evaporate to in space?) It gets locked in rocks in unique chemical way as mentioned earlier. The water also condenses around the dust--the dust then coalesces in the formation of the planetesimals.

The hot planets would be dry of water, and the far ones cool enough to contain the water. So how, then, would Earth and Mars (close planets) have water? There is a really interesting theory for how. Jupiter in its massiveness screwed up the orbits of all the other planets/planetesimals allowing them to mix with the wetter planets so that by the time they were done forming and set on their current and relative position to the sun, water had already been locked deep inside the planets.

I kept getting interrupted during the program so I can't relate all of it. Part of the problem is I don't understand what happens when water gets vaporized. Does it separate back into the original atomic parts? Far as I understand, molecules can be formed and unformed, but their basic elemental parts cannot be changed or destroyed.

Another interesting puzzle was why is the moon dry when the Earth isn't? During the formation of the planets, it is thought there were many mini planets which formed from the dust. The mini planets collide--the debris coalesces around the largest surviving body, and a larger planetesimal is formed, until you are left with 8 major planets. The heat of the collision of the large planetisemal that hit Earth after it had formed 4.5Ga and the two bodies recoalesced---the smaller was more vaporized, thus losing all the water, wheras Earth, the larger of the two bodies, wasn't fully vaporized, so the locked water inside did not get vaporized out. I think it may have been more complicated than that....

They also concluded that asteroids (different than comets, but I missed how) would have also brought water to the planet. Astroid h-ratios are same as Earth's, but also have molecules that are different as well.

They analyzed old water buried deep in the Earth and brought to the surface by hot spots in Hawaii via volcanoes. The h-ratio of heavy to light was different than the ratio of surface ocean water. This tells the scientists that the ratio can change, and therefor water could have come from the comets (which it obviously must have) and also allows the 'water at origin' theory to also work. If water was at the beginning of Earth's formation, what about other planets elsewhere in the Universe? It seems like water must be ubiquitous in its various forms. Somewhere out there it seems inevitable that, among the 100,000,000,000 stars just in this galaxy, and that 10,000,000,000 of them harbor planets and that 1,000,000,000 of them probably harbor water that at least some of them (read: many) must have life.

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Hydrogen is the single most plentiful element in the entire universe, and they wonder why there is some on Earth?

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Gez said:

Hydrogen is the single most plentiful element in the entire universe, and they wonder why there is some on Earth?

They were wondering why Earth's water molecules had a different weight ratio of Hydrogen atoms than the water molecules on the comets that they sampled using a space craft.

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Jodwin said:

Gaia saw Atlas in tiny pink speedos. Voila.

Glad I'm not the only one who instantly thought of a joke like this.

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Hellbent said:

They were wondering why Earth's water molecules had a different weight ratio of Hydrogen atoms than the water molecules on the comets that they sampled using a space craft.


Normal Hydrogen and heavy Hydrogen have a mass ratio of 1:2. No other element is that easy to separate into its isotopes.

Heavy water as a significantly higher melting and boiling point than normal water so again the physical properties are different enough that the ratios may vary depending on what the water was subjected to during its lifetime.

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How did the Earth get wet?

Easy. Chuck Norris had to take a piss, and so he pissed on earth. And, velveeta! Oceans were made!

:D

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Jodwin said:

Gaia saw Atlas in tiny pink speedos. Voila.


Thread over.

I remember in SimEarth, you could get water by crashing comets into your planet.

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Hellbent said:

Part of the problem is I don't understand what happens when water gets vaporized.

It turns into...water vapor.

If water was at the beginning of Earth's formation, what about other planets elsewhere in the Universe? It seems like water must be ubiquitous in its various forms.

There is water on many bodies in our own solar system, so yes.

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Quast said:

It turns into...water vapor.

And then swirls around in space for awhile? Until it cools enough to condense on some space dust?

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eargosedown said:

Ice is all over the place. Much of it water ice.

Our climate is just the right temp for it to be liquid instead of ice.

So?

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Danarchy said:

I remember in SimEarth, you could get water by crashing comets into your planet.

They really need to do a version of this "game" in 3D. It was an awesome concept, but so limited by using 16x16 pixel tiles to represent everything. It wasn't nearly as engaging as it could've been, given how much it was simulating.

By the way, you'd also have water vapor in the atmosphere from the start, which would condense and form oceans as soon as the planet cooled.

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Hellbent said:

And then swirls around in space for awhile? Until it cools enough to condense on some space dust?

No. Outer space is a near perfect vacuum. Atmospheric pressure is non existant, meaning that water can (has to) exist as a gas at such a low temperature. 3 degrees kelvin iirc.

This is counter to how, for example, at the bottom of the deepest ocean trenches, where the pressure is 1000 times greater than at sea level near thermal vents water can exist as a liquid at temperatures nearing 400 degrees F without turning into water vapor.

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The temperature of any water in space will depend directly on how much radiation it gets. If it's close to the sun it might be a gas. If it's behind something and there is a bunch of it together it will be ice. Sure, it's gas if there are some lone water molecules floating around, but I'm sure the meaningful bits are all locked up in ice or rocks (ice in rocks...).

And to answer the confusion of the OP, comets are mostly ice; asteroids are mostly rock/metal.

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Wow. I can't remember someone being so confused by a subject that isn't the least bit confusing.

Earth got its water from *somewhere*. Why do we really need an exhaustive explanation? Is it really such a mindfuck if a single comet had ice with a slightly different molecular makeup than water on earth? I think not.

If there's one thing that annoys me more than people who pretend to understand something they don't, it's people who find mysteries where none exist.

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AndrewB said:

Wow. I can't remember someone being so confused by a subject that isn't the least bit confusing.

Earth got its water from *somewhere*. Why do we really need an exhaustive explanation? Is it really such a mindfuck if a single comet had ice with a slightly different molecular makeup than water on earth? I think not.

If there's one thing that annoys me more than people who pretend to understand something they don't, it's people who find mysteries where none exist.

Welp, science is over. AndrewB has spoken.

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Danarchy said:

Thread over.

rf` said:

Welp, science is over. AndrewB has spoken.

You guys are breaking my heart. :*(

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bytor said:

The planet appears to be sexually stimulated.

I was waiting for it. Took 21 posts before someone finally said it. Well, you earned yourself a virtual cookie.



Just, if you could please eat it from the upper right corner, I'm in New Mexico and would like not to be one of the first to be eaten.

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Hellbent said:

I was waiting for it. Took 21 posts before someone finally said it. Well, you earned yourself a virtual cookie.

The third post read:

Gaia saw Atlas in tiny pink speedos. Voila.


Uhhh...

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LOL Thanks for the cookie, Hellbent!

I'll wait and let Jodwin pick which one he wants.

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Clonehunter said:

How did the Earth get wet?

Easy. Chuck Norris had to take a piss, and so he pissed on earth. And, velveeta! Oceans were made!

:D


*Punches repeatedly*

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