Where did the water come from on earth?

4.0 Billion Years Ago, Earth’s surface cools enough for most of the water that has collected in the atmosphere from comets and volcanic outgassing to rain down to the surface and fill in the basins forming the world’s oceans.

http://www.ccsf.edu/departments/history_...

I just came across this so I thought I would add it.

(Note: atmosphere came first, then oceans, then life, then oxygen in the atmosphere)

Formation of the oceans

1. All gases released into atmosphere from Earth including H2O

a) These gases formed the early atmosphere

b) Initial crust temperature=600C (So H2O and other gases stayed gases)

2. The process that should occur

a) Crust cools to below 100C

b) All H2O would have condensed

c) Acid gases would react with igneous crystal minerals to form sediments and initial oceans

d) Original ocean was an extremely hot, salty ocean

3. What is thought to have occurred

a) H2O, CO2, and HCL existed into the oceans

b) Water (at a slow cooling rate) would condense into an early, hot ocean

c) Then HCI would have dissolved into the oceans

d) Early Acid Ocean reacted with crystal minerals, dissolving silica and catious, creating aluminous clay materials to form sediments on ocean floors.

e) Presence of blue green algae in fossil records more than 3 billion years ago prove surface temperature cooled lower than 100C

4. Degassing

a) Most degassing occurred in the beginning, and only a little bit since (degassing=Earth giving off gases with volcanic eruptions)

The bulk of earths water was there from the beginning but for a long time it was all steam. The earths atmosphere was also about 70 times as dense as it is now. Eventually the earths surface cooled down enough for water to begin condensing and rain down. Alot of water would also have come to earth via comet impacts. So it is not so strange that earth has so much water since the molecule itself is quite common. The real question is: since earth, venus and mars all formed in the same way, howcome those planets have almost no water? It is plausble that mars and venus did have lots of water. Surface features on mars supports this as does the abundance of heavy hydrogen isotopes in venus atmosphere. But both planets have lost their water due to interaction with the suns ultraviolet rays that split water into hydrogen and oxygen. And when the hydrogen is free it can reach escapeenergy and vent off into space.

Nice question !

The planetary picture that is emerging is that Earth was formed with very little water, or no water at all. The hydration of Earth came from comets and some hydrous asteroids. These sources are the Kuiper belt out past Neptune and the Oort cloud on the edges of our solar system. Comets are one of the most primitive members of our universe and due to their remoteness and small size have not undergone much chemical change; they are frozen fossils of a long past epoch. While asteroids are more numerous (70% of visitations to comets 30%) they contain little water, mainly rock and metal.

Water is thought to have been first delivered here over 4 billion years ago involving an intense bombardment of the inner solar system. One such attack is known as the lunar cataclysm, a period of celestial assault when the moon became most heavily pock-marked. The Earth received 13 – 500 times more ‘hits’ and having a greater critical mass was also able to hold much the water (ice); whereas the moon lost most of its frozen water to the emptiness of space. Tantalizing speculation is that some of these comets may have incubated in the Jovian sub-nebula in the space around the gas planets of Neptune, Saturn and Jupiter. Out there some of their chemistry altered to become enriched with the six noble gases (helium, neon, argon, krypton, xenon and radon) and form the different types of water that makes life on Earth possible, such as heavy water and regular light water we live with.

Using spectroscopy physicists discovered that our planets and observable comets each have their own distinctive water signatures. In the depths of space some water is formed when the isotopes of hydrogen, known as deuterium bond with an oxygen ion. They form what we know as heavy water. Whilst it is only 10% heavier it looks feels and tastes like water but has different properties such a higher boiling point (101.4C) and freezing point (3.8C). The Earth’s has is own d/h ratio signature which is 1:6600. Measuring the ratios of deuterium and hydrogen is one way to understand formation and development of comets, as well as observe their residual effects across the solar system.

Water is made of hydrogen and oxygen and there was plenty of these elements present when the earth formed, all that was needed was a small flame to ignite the hydrogen and a chemical reaction combined it with the oxygen to form water. The great heat did cause the water to evaporate but it was still water, it was now in another form and another place, when the earth cooled all of this water vapour which was now water fell as rain, it probably rained for a million years or longer and when it finally eased off the earth's surface was probably covered to a depth of a mile with water.

When the earth was still a lump of liquid molten rock, being held by the gravity of our core, The different types of rock were reacting with eachother. The elements found in them were being compressed and being forced to react with the other elements in the other rocks. These chemical reactions created what we now call our atmosphere. A layer of gases surronding the earth. However reactions didn't stop there. At this point there was no water but there was plenty of Hydrogen and Oxygen in the atmosphere. These, over millions of years, reacted with eachother to form the Blue Planet that we have today.

Part of the water was with the Earth as steam from the beginning (about 4500 millions years), but surely most came from thousand of comets that had fall in millions of years. Another small part would be the result of some hydrogen that the Sun continuously is sending to the space, and in the Earth can react with our oxygen.

Yes, but after millions of years the huge molten rock cooled down, allowing the water to condense.

Because even in the molten lava in the core of the planet, there is still water mixed with it... So when it get out from volcanos, it just vaporized in the atmosphere to fall back later as rain... Also some of it come from fallen comets, mostly made of ice...

mainly from comets, at this time when the earth first cooled off there was basically no atmosphere and then there was the bombardment stages. and without an atmisphere the comets did not burn up in mid air, they hit the ground. and over a long period of time it became water, that we have today/

In my opinion God created earth. And in the view of other people the heat formed clouds of moisture that cloud produced water, the water frozed ice age melted created oceans and rivers LA LA