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)
Where did all the water come from on the Earth?
Chariotmender is bang on. There is a big debate still in the geoscientific community about whether the water on earth comes primarily from the degassing of the initial planetary body (migration of water from the interior to the surface over time) or whether most of the water was added a little later by continued accretion (additions from impacts of small objects wandering around the solar system). Both mechanisms really follow the same idea, that the stuff put into space by the nova responsible for the formation of our solar system included a lot of oxygen and hydrogen and these two compounds got together to form a lot of water. Whether most of that water came onto earth while the planet was forming from the collection of all that space junk or later from the much longer and slower collection of the residual space junk is an open question. One argument is that the early water was blown into space by the solar wind, before the earth had a magnetic field protecting it, and that the water we now have only started collecting after enough iron and nickel had migrated to the core to generate the protecting magnetic field we now have (meaning that even though water came from the inside of the early earth at first, this water did not stay, and water only accumulated after from the comets). Sounds complicated but it isn't, really.
Why does the Earth have so Much Water?
The question has two a two parts answer and two different concepts to answer it. One is planetary genesis. Basically how did our planets formed. The second is the cosmic history shall we say of planets. Planets like Venus, Earth or Mars were formed by condensation of small particules of ice, silica and other cosmic dust. Gravity did its trick and basically water on earth (or other planets) comes from what was once space ice. With the planets mass (and therefore gravity pull) increasing, comets (dirty ice cubes shooting through space) collided with eath increasing its water content. At this point, there is no differences between Earth or Venus or Mars. Condenstion of matter meant that earth was extremely hot at the beggining and formed a gigantic ball of hot magma (lava). Water was solely in gas form (vapor) in the atmosphere. Now this is where things go wrong for Venus and Mars. Venus is hot, too hot. So hot that its water left the planet progressively. Mars on the other hand is not too hot. And being cold wouldn't make it loose water (it would just be ice). Mars is too small. Its gravity pull could not manage to hold on to much atmosphere and very much of the initial water from Mars escaped its gravity pull into space. Some evidence of a cataclismic event finishing Mars and taking the little water that was left is agreed upon by most scientists but the major loss was during its cooling period when it could not hold to its atmosphere. Water is one of the most plentyful substance in space, we could discuss the life of stars to explain this but it's another story and I'm affraid if I go on.... Anyways hope this helps
Where did Earth's water come from?
How did water get here? Comets are mostly water - could collisions with comets have delivered water (and life?) to earth. Also, do we lose water through the atmosphere?
How did water get to earth?
Two main sources are most commonly suggested: 1. Outgassing by voclanoes. Hydrogen and Oxygen are common and combine easily. 2. Comet strikes. Many comets are composed mainly of ice and rock. during the accretion cometary impacts were frequent While the early earth's crust remained hot, water vapor remained in the atmosphere. When the planet cooled it began to rain, and it rained hard for centuries. The low spots on the crust filled with water and became oceans. Then in time anoter large asteroid would hit, the energy released would heat the earth and the oceans would evaporate and the crust would turn to magma. Then slowly it would cool... This cycle was probably repeated many times before the asteroids quit falling.