What is the main resource of water on earth?
Answers
Explanation:
Earth is the only planet in our solar system that is 70% covered with oceans. That was like a riddle for scientists because the crust of Earth was totally dry when it formed. So, from where all the water came?
When fusion started firstly after forming Sun, it vaporized all water and pushed that water vapour quite away in outer solar system (beyond mars today). When earth formed, something took that water back into inner area of solar system where earth was present. That question was like a trouble for scientists but now, they know the reality.
After formation of planets, our solar system was full of upheave due to a violent event called 'Late heavy Bombardment'. There are comets and asteroids everywhere, wondering here and there.
According to astronomers, it happened due to alignment of Gaseous planets. The evidences of late heavy bombardment are hidden in craters of moons. Earth was comparatively larger target. So, scientists thought water came on earth through comets. A comet is made up of water ice, dust and gases. To prove their idea, scientists had to match the chemistry of water of comets with water on earth because every waters are not same. If talking about original chemistry, water is of mainly two types. We all know about normal water. Second type is called Heavy water, in that a simple hydrogen atom (called protium) is replaced by one of its isotope called Deuterium. Hydrogen has three type of isotopes named as protium, deuterium and tritium.
Where protium has only a proton in nucleus, deuterium has a nucleus formed by a proton and a neutron. So, deuterium is two times more massive than hydrogen and that's why the water it formed called heavy water. Water on earth contains a drop of heavy water out of 10,000 drops of normal water. Ok, that's simple. Scientists had to find out the proportion of heavy water in water of comets. In 1986, they had that opportunity when Halley's comet returned in night sky. The result was unexpected. The water found was two times more heavy.
Comet Hale-bopp and Hyakutake were passed beside in 1990 and these comets are as old as ones in Late heavy bombardment. After checking the composition of their water, it was found that both of the comets had many times more semi heavy water. Even in 2014, Rosetta space probe measured the water of nearby comet and it was found three times more semi heavy water than earth. Uff!
Scientists were in trouble because only comets couldn't bring water on earth. And then, a new idea arrived.
In year 2011, Dawn Space Prob passed nearby a giant asteroid named Vesta. Scientists believed that the objects like Vesta were quite dry, but the observation team found the evidences of water on Vesta. And the chemistry of water of Vesta matched the chemistry of earth's water. The water there was resembled to earth's one. So, asteroids were fall on earth and the energy released during collision vaporized whole water inside asteroid and that water came on earth through rain. It may be possible that some of water came through comets, but most of water was came from asteroids, which is in rivers, oceans and even inside us. At least, scientists thought it. But it was not end of story, the water from asteroids was a small part of story. So, sit by the heart and let's see what happened, which confused scientists.
As we know oceans have covered 70% of earth's surface, only Pacific Ocean have crores of cubic miles water. But, most of water is not on surface of earth indeed. I am talking about underground water. How they know it's water under the crust? Seismologists observed it by first time while analyzing the rumbles of earthquakes. After studying these long range rumbles, they came to know when sound waves reaches 480 km inside thrust in singed layers of rock, then their velocity reduces. And it's only a thing which can lower the velocity of sound waves releasing from rocks, it's water. It's not like ocean's water, and it's quite more than ocean's water.