Friday, March 06, 2009

Where did Earth's water come from?

Here's the paradox - Earth seems to be too close to the Sun to have formed with liquid water, so where did we get enough water to cover 70% of the planet's surface?

UA planetary science professor Mike Drake will be featured on this week's episode of the National Geographic Channel series "Naked Science" on the topic of "Birth of the Oceans," which explores where Earth got its water.

Mike discovered that olivine and other common minerals adsorb an astonishing amount of water – enough to create 10 times the volume of water currently found in Earth's oceans. So, his conclusion is that before the planets formed 4.5 billion years ago, an enormous expanse of fine dust grains swirled in a vast sea of hydrogen, helium and oxygen around the sun. Hydrogen and oxygen reacted to make water, creating a disk of basically dust surrounded by water.

Mike concludes that, "At least some, if not most, of Earth's water had to come from adsorption of water onto grains before the planet ever formed."

[parts of this post are taken from a UA news release]


  1. This is a question:
    Since There is no liquid H2O (Water) anywhere in the known universes but Earth.
    How did freshwater and saltwater seperate from each other and create the environments that house all of the different spoecies of life in each? I have never heard of a fresh water Octopus
    except maybe its distant relative the Octomom:).

  2. I wonder about the amount of lightening that occurred over billions of years as a possibility to explain the presence of much of teh Earth's water. We know that Oxygen and Hydrogen is available in much of teh solid materials on earth, and with storms occurring over all that time all around the planet, it seems a likely way to explain the volume of water on our planet.

  3. When you include observations of weather over the whole earth, you get some pretty amazing numbers. Here are a couple-

    Number of thunderstorms occurring at any given time: 2000

    Number of lightning strikes over the earth per second: 100

    (The above numbers from this web site:

    Expanding the lightning numbers... 100 per second equals 6000 strikes per
    6000 per minute equals
    360,000 per hour
    360,000 per hour equals
    8,640,000 per day

    Wendell Bechtold, meteorologist
    Forecaster, National Weather Service
    Weather Service Office, St. Louis, MO

    Now multiply 8 million strikes per day times 365 days a year. It equals nearly 3 billion strikes over a year. No multiply that number times 3 or 4 billion years.
    That is a lot of electricity available to unlock and assemble H2O molecules into a huge quantity of water over that period of time.
    The water from comets theory has been discounted as a significant source so it's time to turn over some more stones.