Where did Earth's water come from?

[Jim Colyer]

I thought Earth's atmosphere came from volcanos and that it rained for a million years to create the oceans.

 

My cousin told me, he heard on a science program that Earth's water came from meteorite impacts.

 

What is true?

[LJP07]

I always thought it came from huge meteorite impacts, and as far as I understand it's from two sources Primary Water and Water from Comets.

 

Two of the elements found in the Universe commonly are Oxygen and hydrogen. They are chemically quite reactive, and so they both combined with various other elements to form chemical compounds. One of these compounds is water, and water quickly became an important part of the earth's surficial layer ( Surficial Layer is the layer which is relating to something happening or being on earth), along with many other familiar chemicals like Silica. Water flowed and flowed which eventually became the oceans as we know it. However, in Earths First Billion years and over the past 4.5 billion years, the main source of water was from comets.

 

We know that comets consist chiefly of chemical compounds that are either gases or liquids at earth-surface conditions: methane is one common component of comets and water is another. Although I am not an expert in this field, that's how I currently understand it.

[hallenrm]

Here's a reliable link from where where you can get some useful information about your question. It is an article in wikipedia for the same topic.

[Turtle]

I always thought it came from huge meteorite impacts, and as far as I understand it's from two sources Primary Water and Water from Comets.

 

... However, in Earths First Billion years and over the past 4.5 billion years, the main source of water was from comets.

 

The water-from-comets idea is now passee.

 

PASADENA -- A new Caltech study of comet Hale-Bopp suggests that comets did not give Earth its water, contrary to the longstanding belief of many planetary scientists.

http://www2.jpl.nasa.gov/comet/news98.html

 

Taken together with the signatures of volatiles on Earth, these data suggest that no more than 50 percent, and probably less than 15 percent, of Earth's water could have been added from space at the end of our planet's formation, says Drake.

http://www.findarticles.com/p/articles/mi_m1200/is_12_161/ai_84546023/pg_1

:D :hihi:

[LJP07]

The water-from-comets idea is now passee.

 

 

http://www2.jpl.nasa.gov/comet/news98.html

 

 

They say in it's caption that it's probable that water didn't come from comets after all. There is proof of comet bombardment 4.5 billion years ago therefore, water must of came from them, maybe not all, but a significant amount. That first link said probable so I won't take it as fact.

[HydrogenBond]

What makes the most sense, is that the solar system stuff from which the sun and planets would form created its own density gradient, making the inside planets denser and the outer planets gaseous, with plenty of water, hydrated onto dust, concentrated where the earth would form. I am glad the comet theory for water was put to rest. Comets will also someday be put to rest with respect to the seeding of life. The earth had all it needed to get the job done, i.e, water and organics.

 

What is sort of interesting; if one placed a block of earth crust in a vessel and placed water on top, sealed it, and then heated it to the critical point of water, and then set up a thermal gradient, i.e, top cool and bottom hotter like the earth, the critical water will dissolve its way to the bottom, with the minerals in the crust crystallizing on top, even though the water has a lower density than the crust. A chemical potential drives the process. This is one way to make synthetic crystals like quartz and emeralds. If we reverse the thermal gradient (hot-top), the water would go up and crystals would form on the bottom. The earth has hot down instead of up. This earth design allows critical water to dissolve its way into the mantle replacing solids behind it.

 

One may ask, if water is in the mantle why do volcanos mostly have minerals and not too much water? The answer is simple, the water is displacing the minerals up.

[pmaust]

I thought Earth's atmosphere came from volcanos and that it rained for a million years to create the oceans.

 

My cousin told me, he heard on a science program that Earth's water came from meteorite impacts.

 

What is true?

 

Many years ago, PBS aired a series called Miracle Planet. That series delt with the formation of the universe, solar system, and planets as I recall. Anyway, in one of the episodes, they demostrated how by adding heat to meteroite material water would begin to vaporize and then cool and condense into liquid form. The source water was trapped inside the meteorite material. It was postulated that as meteorites and other space stuff fell to the surface of the forming earth, the water was released due to the heat. Before there was sufficient gravity and atmosphere, the water vapor would simply return to space. Later, it began to get trapped in the forming atmosphere where later it condensed and rained down onto the earth surface.

 

The demonstration of releasing trapped water from space debris by the addition of heat sure made it appear like a plausible explanation.

[HydrogenBond]

One of the reasons water was speculated to come from comets, is comets are also needed to form the earth's supposed iron core. Without comets and because the earth is mostly oxygen as oxides, the iron core would have never phase separated from a starting cloud of ingredients. In other words, if one starts with iron plus oxygen one gets iron oxide. To form metallic iron one needs a reduction potential. Simple gravity will not separate out the iron, only iron oxide would settle in the core, not iron.

 

An abundance of hydrogen or carbon on the forming earth could provide this reduction potential but the amount of water or CO2 left on the earth should be much higher than observed, since the core is 10,000 times bigger than the oceans. The work around this practical constraint was to use comets to get the iron into the core very quickly before oxidation. The water became a bonus. Now the bonus is not considered correct. Comets for the core remains due to lack of challenging data. It is a theory needed to protect another theory.

 

Another conceptual problem with the comet theory is that the earth should not have been the only planet or moon formed by comets. There should be far more uniformity in all the rocky planets and their moons. All should have iron cores and all should have water. Venus has plenty of CO2 which is more volatile than water. I guess Venus was bombarded by specialty CO2 containing comets. To assume only the earth was in the path of a particular comet composition is absurd. It really came down to needing fresh absurdity to get politians to cough up resources. The hope was to slip it by common sense long enough to get resources, until data proves otherwise. This allows double the resources to disprove absurdity bringing us back to square one.

[Tormod]

Well, the comet theory isn't entirely dead. The Deep Impact project last summer proved that comets can contain immense amounts of water. It spouted water for days after the impact.

 

There was also (to the scientists' surprise) water ice on the surface:

 

http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact_water_ice.html

 

A chief scientist said (early this year):

 

"Understanding a comet’s water cycle and supply is critical to understanding these bodies as a system and as a possible source that delivered water to Earth," she said. "Add the large organic component in comets and you have two of the key ingredients for life."

 

Which shows that the water-from-comets idea is far from passe, nor is the life-from-comets idea dead.

 

Edit: The "death-from-comets" theory is still alive, too.

 

I do agree with HydrogenBond that life may well have come about on Earth without the help of matter from comets. Some have speculated that comet impacts may have caused impact fragments to blast into space and carry life between the planets (ie, we could all be Martians :D ).

[ezguine]

Hello, a response to a very old post.

I believe that earth's water is the ashes of a former atmosphere consisting mostly of hydrogen which at some point was ignited and the whole atmosphere flashed into flame. The resulting compound from the chemical reaction is today's water. Just thought I'd throw my late opinion out there after coming across this post on Google

[freeztar]

Hello, a response to a very old post.

I believe that earth's water is the ashes of a former atmosphere consisting mostly of hydrogen which at some point was ignited and the whole atmosphere flashed into flame. The resulting compound from the chemical reaction is today's water. Just thought I'd throw my late opinion out there after coming across this post on Google

 

Do you have evidence to support your idea?

 

One very serious problem I see with this is that the H2 would need O2 to ignite and create water. Current "early Earth" theories assume that the O2 was created by ocean living bacteria. In other words, in order to have the oxygen needed to create such an ignition, you would have to have water first.

[Moontanman]

Hello, a response to a very old post.

I believe that earth's water is the ashes of a former atmosphere consisting mostly of hydrogen which at some point was ignited and the whole atmosphere flashed into flame. The resulting compound from the chemical reaction is today's water. Just thought I'd throw my late opinion out there after coming across this post on Google

 

That's an intersting idea, just what other chemical did the hydrogen react with and where did it come from?

[raymond723]

I think it's from the ocean or outer space

[JMJones0424]

I love this site, I find new things to stimulate my mind every day.

 

I have no evidence to support this, not sure when/where I heard it, I may even have dreamt it up.

 

I thought that water vapor, in the absence of a magnetosphere created by a moving liquid core, when exposed to solar radiation, would split into hydrogen and oxygen. In the upper atmosphere, the hydrogen would be blown away by solar wind. This explains why H2 is rarely found in the smaller, closer rocky planets. By this reasoning, Mars likely had water when it had a magnetosphere. But since the core has solidified and solar radiation was allowed to penetrate the atmosphere unimpeded, it lost the majority of its water by losing the hydrogen. The excess oxygen combined with other elements, leaving the only remaining water that which is protected from evaporation underground.

 

Same process on the moon, but more rapid due to less atmosphere and gravity, and probably less water to begin with if the moon is considered to be the leftovers of a massive strike by a protoplanet early in the history of what became the Earth.

 

Never really looked into Mercury or Venus, they rarely peak my interest.

 

Like I said, this is probably entirely wrong, just what I had thought. If it is wrong, why?

[freeztar]

I love this site, I find new things to stimulate my mind every day.

 

I have no evidence to support this, not sure when/where I heard it, I may even have dreamt it up.

 

I thought that water vapor, in the absence of a magnetosphere created by a moving liquid core, when exposed to solar radiation, would split into hydrogen and oxygen. In the upper atmosphere, the hydrogen would be blown away by solar wind. This explains why H2 is rarely found in the smaller, closer rocky planets. By this reasoning, Mars likely had water when it had a magnetosphere. But since the core has solidified and solar radiation was allowed to penetrate the atmosphere unimpeded, it lost the majority of its water by losing the hydrogen. The excess oxygen combined with other elements, leaving the only remaining water that which is protected from evaporation underground.

 

Same process on the moon, but more rapid due to less atmosphere and gravity, and probably less water to begin with if the moon is considered to be the leftovers of a massive strike by a protoplanet early in the history of what became the Earth.

 

Never really looked into Mercury or Venus, they rarely peak my interest.

 

Like I said, this is probably entirely wrong, just what I had thought. If it is wrong, why?

 

I wouldn't say that it is wrong. Photodissociation is a commonplace event in the atmosphere of Earth. I highly reccomend that you visit the thread "H2 escape into space"

 

Good stuff there and in the linked threads/links! :)

[Turtle]

Science is always amendable. :smart:

 

Interplanetary Dust Particles Can Deliver Water and Organics to Terrestrial Planets: January 27, 2014

 

...

Researchers from the University of Hawaiʻi at Mānoa’s School of Ocean and Earth Science and Technology (SOEST), Lawrence Livermore National Laboratory, Lawrence Berkeley National Laboratory, and University of California – Berkeley discovered that interplanetary dust particles (IDPs) could deliver water and organics to the Earth and other terrestrial planets.

Interplanetary dust, dust that has come from comets, asteroids, and leftover debris from the birth of the solar system, continually rains down on the Earth and other Solar System bodies. These particles are bombarded by solar wind, predominately hydrogen ions. This ion bombardment knocks the atoms out of order in the silicate mineral crystal and leaves behind oxygen that is more available to react with hydrogen, for example, to create water molecules.

...

"In no way do we suggest that it was sufficient to form oceans, for example,” said Ishii. “However, the relevance of our work is not the origin of the Earth’s oceans but that we have shown continuous, co-delivery of water and organics intimately intermixed.”

 

In future work, the scientists will attempt to estimate water abundances delivered to Earth by IDPs. Further, they will explore in more detail what other organic (carbon-based) and inorganic species are present in the water in the vesicles in interplanetary dust rims.

...

[Boerseun]

Seeing as the Earth initially formed through the coalescence or the same stuff orbiting the juvenile sun that resulted in the comets, I fail to see the problem. Ultimately, the water in the comets, the water in the above-mentioned interplanetary dust particles and the water in the Earth's seas all come from the same source - the first generation star that preceded our sun in this neck of the woods blew up and burped a lot of crap, among which oxygen, into space. And eventually that oxygen found its way to stray hydrogen floating around that either survived the first-generation star's explosion or was captured from an interstellar hydrogen cloud. And vóila - water. THAT's where our water comes from. Comets or interplanetary dust particles are merely intermediary steps that could contribute, but they're nothing more than middlemen in the process, because they originally got their water from the same source.