Earth may have underground 'ocean' three times that on surface

[Wyrd of Gawd]

Do you have any idea how many comets it would have taken to bring all of the water to Earth? You guys are insane! The Earth makes its own damn water as well as its own gases and petroleum.

[JuliaL]

Do you have any idea how many comets it would have taken to bring all of the water to Earth? You guys are insane! The Earth makes its own damn water as well as its own gases and petroleum.

Ummm....six?
But they're really big ones.

[Welsh cake]

If plate tectonics does not stop, then the subduction process will likely consume all the oceans on the surface of the earth long before the sun goes red giant.

Wouldn't that just turn it into steam?

[Mystical]

Do you have any idea how many comets it would have taken to bring all of the water to Earth? You guys are insane! The Earth makes its own damn water as well as its own gases and petroleum.

Shit happens. In the billions of years that this planet has been around, I'm sure a lot of shit has happened. And not just one shitstorm at a time, either! I'm sure if we ever get to studying other planets and shit, we will be able to see how shit works. Until then I see no reason to believe in shit that has no evidence on the surface of this planet other than books written by people who couldn't possibly confirm their own shit.

That's my (shit expert) opinion on the matter.

[Anomalocaris]

If plate tectonics does not stop, then the subduction process will likely consume all the oceans on the surface of the earth long before the sun goes red giant.

Wouldn't that just turn it into steam?

No. As the water in waterlogged sediments on the bottom of the ocean gets dragged down into the subduction zone, increasing pressure keeps the water from flashing into steam until the sediments reach anywhere from 50-200 miles deep. At that depth the pressure and temperature becomes so high the most of water chemically combines with the mantle rocks to form hydrated minerals. Only a small portion of the this water then come back up as part of the material that makes up volcanic magma. If the magma erupts onto the surface as lava, then the water will boil out of the lava as steam. The the steam is a tiny percentage of the total water that was originally dragged down into the mantle.

So plate tectonics is in effect gradually mopping up the water in the ocean, and squeezing the water into a essentially bottomless, and only slightly leaky, reservior in the mantle.

[Mystical]

I'm so excited about this!

Any idea on how hot the water would be? Or how deep an ocean?

[Jackalope]

I'm so excited about this!

Any idea on how hot the water would be? Or how deep an ocean?

"Ocean" is a bit of hyperbole. The water is locked up in the mantle, it's not liquid water.

[Mystical]

????

[Anomalocaris]

Do you have any idea how many comets it would have taken to bring all of the water to Earth? You guys are insane! The Earth makes its own damn water as well as its own gases and petroleum.

1st, you have to get an idea of how many comets there were in the protoplanetary nebula around the infant sun, and how many of them still remains.

There is probably about a trillion comets still orbiting the sun. There were probably a hundred or a thousand times more when the planets were forming.



During earth's formation, something like ten billion comets collided, merged, and coalesced to add their material and water to earth.

Basically, for a period of about ten million years after progenitors of earth first started to form in the protoplanetary nebular around the sun, roughly ten thousand Haley's comet's worth collided with the progenitor components of the earth each year.

Roughly one Haley sized comets every 40 minutes for roughly ten million years. That's the ball park of how many comets it took.

Most of the water the comets took with them evaporated back out into space during initial and subsequent collisions. But many oceanfuls of water remained behind on earth.

[corrected and order of magnitude error]

---

????

Yeah. The water in the mantle is chemically bounded to the rocks. It's not in a liquid state. These rocks won't even feel wet if you somehow can touch them.

[Cyberman]

Do you have any idea how many comets it would have taken to bring all of the water to Earth? You guys are insane! The Earth makes its own damn water as well as its own gases and petroleum.

I don't think anyone is arguing that it either has to be one or the other (well, apart from you, obviously). It could be and most likely was both. Considering that hydrogen is far and away the most abundant element in the Universe, with the next most abundant reactive element, oxygen, coming in third (the second most abundant, helium, is chemically inert), it would be more surprising if proto-Earth didn't produce the stuff. Comets (ie the boring, bog-standard variety as distinct from the magic ones) still played their part. The Solar System is a shooting gallery; the formative one consideraly and quite insanely so. Cometary colliisions can and do happen - we've actually seen it.

You seem to be under the impression that we're saying first there was the Earth, and then the comets came with their water delivery. If so, you're neglecting the very real fact that protoplanetary collisions are how planets are actually formed. It's not that these comets slammed into the Earth - for the most part, they became the Earth.