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A current theory is that a majority of the Earth's water came from ice-containing asteroids during the formation of the planet and during the period of Earth history known as the period of heavy bombardment.
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While the above is correct, it should be noted that agreement on the origin of earth's water is not settled and is currently a topic of much scientific debate and research.
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And for a third perspective:
It is true that the theories of how water formed on Earth are subject to debate and the opinions have changed over time, so this is not settled.
That said, there are only three ways Earth could have gotten its water.
1. Water was present when Earth was originally formed from the gas and dust cloud that created the solar system and was part of the original mass that condensed to form Earth.
2. Water was delivered to Earth after the initial formation, primarily in the form of a cometary bombardment. Comets at the time of Earth's early years would have been nearly the same composition, with much water, as they are now. There is much reason to believe that all planets have had significant bombardments.
3. Water, was formed by combining hydrogen and oxygen through chemical processes to form water after the initial formation of Earth. (There are good chemistry reasons to expect this was unlikely.)
Though all three occurred to some degree, the real debate is over how much.
A more thorough discussion of these and other possibilities is provided in the related links.
What else can I help you with?
Where does water come from in the process of photosynthesis?
Water is absorbed by plants from the soil through their roots, and it is then transported to the leaves where it is used in the process of photosynthesis.
What happens when many water molecules come into contact with one another Explain?
When many water molecules come into contact with one another, they are attracted to each other due to hydrogen bonding. This attraction causes the water molecules to stick together and form cohesive forces, which results in surface tension and the ability of water to stick to surfaces.
When do cockroaches typically come out during the day?
Cockroaches are nocturnal insects, meaning they are most active at night. They typically come out during the night to forage for food and water.
Water within cells is called?
There's no name for such a fluid, because the body can't 'produce' water. No water that didn't go into the body earlier can come out of it.
Where do the oxigens atoms in the O2 produced during photosynthesis come from?
The oxygen atoms in O2 produced during photosynthesis come from water molecules (H2O) that are split during the light-dependent reactions in the chloroplasts of plant cells. This process, known as photolysis, releases oxygen as a byproduct.
When you breath where does the water come from?
How does water come out of the air?
Did humans come from water?
human life cell come from water
Does water come from a plant?
A water plant. Water doesnt come from there. It is usually filtered there and then distributed from there.
Where did most of the water of the earth come from?
from where did earth water most likly come
Where do dolphin mammals come from?
they come from the water
Where do cloweds come from?
They come from water that evaporates
Where does half of the water used in Texas come from?
Where does most of the water come from in freaking Texas?!
How does hot water come to your faucets?
Through magic hot water elves. That's how hot water does come home.
Where does the water from a shower come from?
Water main
Where does water from a shower come from?
Water main
Where does water from wells come from?
Water wells are come from under ground water and its contain dirt and rain water.
Where does the water in the urine come from?
The water in your body and the water you drink
