So Where Did The Water Come From....

[ToraToraTora]

http://www.bbc.co.uk/news/science-environment-30414519
Comets have up to now been a possible answer so what are the other theories?

[Old_Geezer]

Saw this on the morning TV news.

What I am unclear about is, even if the comet they landed on was typical and it isn't comets that brought the water (and of course that may not be the case) then why suggest asteroids are the alternative ?

I'm no expert but my understanding was that comets formed further out and retained ice/water, whereas asteroids formed closer to the sun and lost their water. It seems a strange second choice delivery system to me.

[Old_Geezer]

I trust heavy water can nor change to the more usual stuff over time. Perhaps it just lost it's deuterium through years of sloshing about. But they'd have thought of that and ruled it out, I guess.

[jim360]

Can't say I fully understand it myself, I'm no astrochemist, but on the face of it they aren't worried about the amounts of water that arrived (with enough asteroidal collisions in the early life of the planet, it wouldn't matter that asteroids were fairly dry) but about the chemical composition. Hence if asteroids have the right composition and ratios they become a viable candidate even with less water per asteroid (and I suppose in the early solar system they could have been wetter anyway).

But I also understood that this was a preliminary result, so it's possible that more data will change the answer. Still an interesting potential discovery, though.

[Slapshot]

Just another of those things that dictate the one simple tenet of science... "Keep asking why"

It just goes to show that for all the incredible science out there we still really don't understand our own planet and the effects that the environment has on it. If we don't understand something as fundamental as water and especially where it came from what else don't we really understand???

[solvitquick]

The universe is composed of chemical atoms, defined in the Periodic Table, and Nothing Else. These atoms have different tendencies to combine depending on their electron distribution about their nucleus, notably by their outer electron distribution. They "prefer" to have an even pairing of the outer electrons. That's why single hydrogen atoms do not exist - they join together to form a H2 molecule (sorry, 2 should be subscript). However when two H2's meet one oxygen (also "happier as O2), the thermodynamics favour the formation of 2x H2O or water.
All atoms and molecules keep bouncing around at even low temperatures above absolute zero. So water and many other molecules are spontaneously formed throughout the universe. These molecule-formations are ofter accelerated by a surface (e.g. a silicon-based dust particle) so this could then gather water molecules and dust with eventual comet formation.
Chemical reactions can take place even between frozen molecules thro' the molecules flying off the surface and meeting. But isn't the universal space empty? Well yes and no because atoms and molecules are themselves mainly empty space. But finally the space between stars/galaxies are almost certainly full of molecules from the commonest atoms like hydrogen and oxygen, hence water. Nothing special about finding water in cold space or on its contituents.
SIQ.

[EDDIE51]

Its easy, God said 'let there be water' and so there was!

[solvitquick]

The juvenile Earth did not need water from outer-space for life-formation or for its beautiful current inorganic blueness. All the Earth needed was to use its own hydrogen and oxygen accumulated during its formation.
Remember around the Earth's iron-core is a mass of silicon dioxide composed (basically) of silicon, hydrogen and oxygen. That earthly hydrogen and oxygen in the silicon dioxide didn't come from asteroids or comets so why did our water need to?
Why in the scientific search for extra-terrestrial life should astrophysicists be searching for Earth-like planets with the primary criterion of them containing water if they did not believe our own Earth was life's breeding ground?
Because they know that our life-forms began here and the key to life-formation is the miraculous solvent for so many chemicals and is a key reactant in the buildiing of complex molecules - water.
Good question TTT, as water is the be-all and end-all of life but it's much underestimated 'cos we just have to turn on the tap.
Water is the staff of life and possibly of the whole universe as we understand it today. Hydrogen is truly the God-molecule fuelling the stars. And Oxygen is the God's Queen as far as life is concerned.
Anyway, that's my view for what it's worth and it confines asteroids and comets to the mere interesting.
SIQ.

[mibn2cweus]

In considering where all of Earth's water came from it might be worth noting that in relation to the rest of the Earth, water is virtually . . . a drop in the bucket.

http://www.universetoday.com/65588/what-percent-of-earth-is-water/

[solvitquick]

Dear mibn2cweus,
Sure, I know that water per se is a small fraction of the Earth's composition.
Ty for your very interesting reference though.
The critical thing however is water's unique chemical and physical properties as I pointed out earlier.
Most of our Earth is now composed of relatively inert (non-reactive chemicals) like complex silicates. Its iron-core is free from oxidation (rusting) because of the lack of oxygen at the core.
Please ask yourself why astrophysicists, when looking whether life ever existed on e.g. Mars, are concerned as to whether water/ice is still hidden below the surface by burrowing into that surface (where it might now be protected from the sun's irradiation). I guess, eventually that water/ice will be found on Mars. In fact, look for it deeply enough or anywhere including on comets or asteroids and you will find it - just chemistry and thermodynamics. But that only suggests that life (e.g. bacteria) might have existed there.
It's not about the percentage of water but rather its unique chemical and physical properties that count. Your pituitary and hypothalamic glands are only a tiny percentage of your body-weight but you would not exist without them! So we can't play the percentages game on this subject.
I know I have concentrated on water in relation to life on earth and elsewhere, but I believe that is what Tora Tora Tora's question and the comet/asteroid research is all about.
A biassed finale: it's really astrochemistry using physics as the booster:)
Kind Regards,
SIQ.

[Sparky22]

Just throwing a curveball at ya but isn't it possible that this was an icy planet and when hot asteroids/meteors hit it they melted the ice and the oceans were born?

[solvitquick]

Dear Sparky22,
Ty for your curveball - most welcome.
I hope I have not given the impression that I know all that much. In fact at my age I've forgotten more than I ever knew. If my posts seem to give an impression of dogmatic statements of facts that's my fault. They are just my deductions as a retired chemist and are supported by many superior scientists to me.
Sure your idea is welcome and good to see that TTT has "sparked" an interesting debate.
Forgive me if I bat your ball into the long grass for now - but others might not and I would love to hear from them.
I just think that all scientific questions should begin their answers with the simplest. That's called Occam's Razor - google it if you are too young to have heard of that. Why search for complex reasons when the simplest is that long ago the Earth was fortunate(?) to spawn life via spontaneous atomic and molecular reactions and the evolve into us?
However time might well prove you right and me wrong! Fair enough, Sparky - nice creative idea.
Kind regards,
SIQ.