Where did Earth's water come from?

Question

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?

Answer 1

I can think of two possible ways to answer your question and I don't know
which kind of answer you are looking for, so I will give you both.

First, the water in the ocean, and indeed all the water in the world, is
involved in a continuous process called the water cycle. Most of the water
that is involved in the water cycle is in the ocean (more than 97%). Water
leaves the ocean chiefly by evaporation, and it returns to the ocean by
precipitation, via rivers and streams, and via undersea springs. The total
amount of water in the ocean doesn't change much. During the ice ages sea
level fell by more than 100 meters (more than 300 feet), and if all of the
existing glacial ice melted sea level would rise by an alarming but smaller
amount. However, from year to year the ocean volume changes little.

Second, one can ask the question: Where did all this water come from in the
first place? As I understand it, there are two main sources: primary
water, and water from comets. When the earth coalesced out of the
primordial gas cloud that surrounded the young sun, hydrogen and oxygen
were two of the chemical elements incorporated in the earth. Hydrogen is of
course by far the most common element everywhere in the universe: you can't
form a planet without hydrogen. Oxygen is less abundant in the universe,
but it is a common element too, if you don't consider the "biggies",
hydrogen and helium. Oxygen and hydrogen are chemically quite reactive, and
so they both combined with various other elements to form chemical
compounds. One of these compounds is water, and water quickly became an
important part of the earth's surficial layer, along with many other
familiar chemicals (silica - a major component of sand, calcium carbonate -
what limestone is made of, etc.). If water existed on earth only as a
solid, then there would be no oceans as we know them, but water can readily
exist as a liquid under the pressure and temperature conditions that hold
on many parts of the earth's surface. Liquids run downhill, and so liquid
water accumulated in low places. There is a lot of water, so some low
places contain huge amounts of it - we call these oceans.
Over the past 4.5 billion years earth has been hit by many comets. We
know that comets consist chiefly of chemical compounds that are either
gases or liquids at earth-surface conditions: methane is one common
component of comets and water is another. A significant amount of earth's
water has probably been delivered by comets, especially in the first
billion years or so after earth formed. During this time the solar system
was filled with debris: small objects that coalesced from the primordial
gas cloud. After a billion years or so, most of these objects had hit
something, and airless bodies like our moon show many huge craters dating
from this period. The Oort cloud of comets out past Pluto and the asteroid
belt between Mars and Jupiter contain many of the small objects that have
not yet slammed into planets or the sun.

Hope this helps.

Answer 2

It used to be thought that the Earth's water came from sources on the Earth such as volcanic eruptions. Some water does come from volcanic eruptions, but it is now thought that most of the Earth's water came from comets which hit the Earth. Since comets are made of ice, it is probable that a number of them melted and brought water to the Earth.

Answer 3

Water is the most abundant solid in the universe. Our planet was formed from a mass that included large amounts of water. Much of the water on Earth (being lighter than silicates) ended up at or near the crust as the planet formed.

Answer 4

Drinking water comes from one of two sources: ground water or surface water. Ground water originates from precipitation that falls in the form of rain or snow and seeps into the ground, filling the open spaces, or pore space, within layers of sand or gravel (formations) beneath the land surface. Under the ground there is a zone of saturation where the subsurface is completely saturated with water. Layers of sand and gravel in this saturated zone are called aquifers. An aquifer is a geologic formation containing water in quantities sufficient to yield water to a well. The well pumps water to the surface where the water company treats it to ensure that it is safe to drink. It is then pumped into a storage tank and upon demand by the customer, flows through distribution pipes into the home and ultimately to the faucet. Approximately two thirds of Louisiana residents obtain their drinking water from ground water.

Surface water also originates from precipitation. The precipitation reaches the land surface and recharges rivers, lakes, wetlands, and other surface water bodies directly. Water is pumped from the water body to a treatment plant and then follows the same path as ground water on its way to the consumer.

There is a finite amount of water on earth. The water on earth is used over and over again. The water cycle, or hydrologic cycle, is the continuous movement of water from ocean to air and land and then back to the ocean in a cyclic pattern. The sun heats the earth's surface water (lakes, rivers, oceans, estuaries), which causes it to evaporate. Then the water vapor rises into the earth's atmosphere where it cools and condenses into liquid droplets. The liquid droplets combine and grow until they become too heavy and fall to earth as precipitation, recharging the surface water bodies and infiltrating into the ground, recharging the ground water.

Answer 5

All of the water on the earth was created when the earth was formed, it has not decreased or increased since.

Answer 6

God

Unless you have synthesis on how to make it than you can say God.