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How do we have the amount of water we do on this planet?

  1. Sep 5, 2015 #1
    I have reasoned that if i go by the assumption that i am here and the universe is as it is, the only things i can really understand are gravity, time and the study of nature (feel free to disagree)

    What happens at the time of death will be a topic for debate long after i have reached that point so i'm not even going to bother with that one. However water is an interesting one!!

    Please feel free to correct me but the way i understand how water came to be on this planet is that when the earth was cooling down water vapour was released from rocks, and the rest of the water we have must have presumably been delivered via an extra terrestrial source like comets and what nots??

    Now i have read in numerous places that there is roughly 326 million trillion gallons of water on the planet. Has there been any studies into how much water vapour could have been released? Though i know those kinds of calculations are way above my head, they must be possible. I would like to find out the total amount of water we had before the bombardment for space...any thoughts??
  2. jcsd
  3. Sep 5, 2015 #2
    I have read that no one knows where the water came from. The most popular theory is asteroids. Or it could be that there were multiple significant sources.
  4. Sep 7, 2015 #3


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    Has one tried to do some research on "Origins of water on earth" via a search engine.

    One possibility - http://news.nationalgeographic.com/news/2014/10/141030-starstruck-earth-water-origin-vesta-science/

    Normally, hydrated rock has to be heated to release water.

    Note there are 'icy' moons around Jupiter and Saturn, and the rings around Saturn contain water. Comets and various trans-Neptunian objects contain ice.

    Also see - http://blogs.scientificamerican.com...-water-on-cometary-origins-of-earth-s-oceans/
    http://neo.jpl.nasa.gov/news/news008.html [Broken]

    Deuterium can be formed in stars, but also outside of stars through simple neutron capture by protons. Neutrons can be formed by interactions of various nuclei with solar protons and cosmic rays (high energy particles) in so-called spallation reactions. One could have to measure the D/H concentration in a comet to see if it changes with time and if so, at what rate is changes.
    Last edited by a moderator: May 7, 2017
  5. Sep 7, 2015 #4

    D H

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    I'm not thrilled with pop sci articles such as that one. The problem is the title, "Mystery of Earth's water origin solved." It should have been "Scientists claim to have solved mystery of the origin of Earth's water (but others agree to disagree)."

    There are three leading contenders regarding the origin of most of the Earth's waters:
    - It came here early (e.g., the cited article),
    - It came here mostly during the late heavy bombardment via wet asteroids,
    - It came here mostly during the late heavy bombardment via comets,

    Each hypothesis has its pluses, but also its minuses. You can find advocates of each in the scientific literature, even as of 2015.
  6. Sep 8, 2015 #5


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    Maybe is should be "Scientists claim a hypothesis or potential solution to the puzzle of the origin of Earth's water," but that wouldn't be a catchy headline.

    I would certainly prefer that National Geographic and Scientific American didn't sensationalize their content or headlines.
  7. Sep 8, 2015 #6


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    One way to look at it is to realize that the three most abundant elements in the universe are hydrogen, helium and oxygen. Given this, it isn't really a surprise that water is ubiquitous.
  8. Sep 19, 2015 #7


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    S.daniels009, welcome to PF.
    Water is here. If water was not here you would not be here.
    You are here. If you were not here you could not ask the question "why water is here".
    It all becomes very self-referential.
    We can only guess at reasons for the presence of water, we can never be certain.
    It is liquid water that is so very special for us.
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