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

[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.

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.

There is one school of thinking which postulates rapid and energetic formation of earth, which left the earth almost completely molten after initial formation. In this scenario, most of the water the earth acquired during its formation was either boiled off into space with the heat of formation, or only stayed by remaining chemically locked up in its mantle. Surface water actually mostly came from a later period of impacts which occurred after the surface of the earth cooled and crusted over.

Violent formation of the moon scenario by giant impact between earth and a mars sized protoplanet also argues that earth must have lost much of its initial inventory of water to evaporation after its formation, and water in its ocean came later in an episode of cometary collisions distinct from the original formation of earth. In this scenario if the earth wasn't molten right after it formed, it was after it got wacked by the mars sized protoplanet.

I think recent evidence argues for a less energetic mode of formation, in which earth was always comparatively cool and had a solid surface more or less from beginning and retained much more of the water that came with its original formation.

There is also evidence the more water than previously thought could have survived the moon forming collision without being boiled off into space. If the moon forming impact was energetic enough to boiled off most of the water from the earth's mantle, it would be energetic enough to boil off all the water in rocks actually blasted into orbit to later form the moon, and moon rocks should be bone dry.

But moon rocks seem to have a lot more water than previously thought.

[Wyrd of Gawd]

Any planet with an active hot core like Earth's will produce its own water, gases, and petroleum. Thinking that comets supplied the Earth with its water is similar to believing in angels.

[Mystical]

I just wanted to thank you guys for explaining this stuff to me Maybe Mars has the same thing, no?

[Wyrd of Gawd]

Mars is not as lively a planet as the Earth is so its internal processes are different. But It could have deep pockets of water and petroleum left over from when it was more active.

[Mystical]

I have a question while we're talking about mars... lol.
Chuck, Stimbo? Can you just open up an "ask Chuck and Stimbo science stuff" thread?

[Anomalocaris]

Any planet with an active hot core like Earth's will produce its own water, gases, and petroleum. Thinking that comets supplied the Earth with its water is similar to believing in angels.

No. Believing earth makes its own water instead of getting it from comets is similar to believing in angled because it goes against everything we know about chemistry, geochemistry and astrophysics. The very first, and insurmountable, problem you will encounter in trying to construct any scientifically plausible scenario of earth making its own water is earth lacks the raw material - hydrogen - to make water. Earth lacks adequate gravity to hold on to any free hydrogen, there is no plausible hydrogen containing compounds, besides water, that could have delivered chemically bounded hydrogen to earth in the amount necessary to make the water on earth. So the only way earth could have acquired the raw material to make water, is by getting it from cometary water. So earth water came from cometary water.

Cometary delivery of water, on the other hand, is consistent with our understanding of stellar formation, stellar chemistry, as well as multiple lines of direct observational evidence. It is not like believing in angles.

You need to stop beating this dead horse.

[Wyrd of Gawd]

There are pictures of water coming up from the ocean floor through vents. But I guess some people seem to think that when it rains it's the magic comets delivering their water to Earth.

[Anomalocaris]

There are pictures of water coming up from the ocean floor through vents. But I guess some people seem to think that when it rains it's the magic comets delivering their water to Earth.

Ah, no. The water coming out of undersea vents were not made in the earth. They are actually water that was originally already in the oceans, which then seeped into the bedrocks under the sea floor, got heated by volcanic activities near the oceanic spreading enters, and then came out under pressure.

You need to understand earth has multiple hydro cycles that move water between atmosphere, oceans and rivers, and underground. The rain, the springs, the geysers, the hot undersea vents, all just represent preexisting water being moved through hydro cycle. None of it involves newly created water coming out from where they were being made. Earth does not make water. Never did. Ever. Earth has acquired large inventory of water, all were delivered by comets, 99% of it was delivered to earth within the first few hundred million, possibly as few as 1-10 million, years of earth's initial formation 4.6 billion years ago.

Your fixation of "magical impossibility" of amply documented cometary water delivery is getting ridiculous.

[Cyberman]

There are pictures of water coming up from the ocean floor through vents. But I guess some people seem to think that when it rains it's the magic comets delivering their water to Earth.

Needs more straw.

[Wyrd of Gawd]

Even the average nuts who advocate the magic comet theory say that it could have taken up to a couple of billion years for the comets to have brought all of that water to Earth. Now it's down to as little as 1 million years? It's a good thing that they don't hit us today with that frequency. If a gold or diamond comet slams into my backyard can I keep it?