Water is a very abundant compound on Earth. About three-quarters of the world is covered with water. The total volume of water on the earth is about 1.386 billion cubic kilometers. In terms of mass, there are 1.386×10 to the 17th power (ton), which is 13.86 billion. Ton. This is undoubtedly an astronomical figure.
So where does so much water on earth come from?
Viewing the earth from space is a blue water polo
1 Let's start with the simplest and most essential question.
water, what is it?
Many people know that water is an important substance that constitutes our life. Water is a colorless, transparent and odorless liquid.
Water is a magical substance
Those who have read physics and chemistry know that water is a compound composed of hydrogen and oxygen, and the chemical formula is H20. The scientific study of water goes back to the 16th century.
Schematic diagram of water molecule
16th century, a famous doctor Palases, he described that a kind of gas is produced when iron filings come into contact with acid.
In the 17th century, Helmont, a well-known scholar of medical chemistry in Belgium , also had accidental exposure to this gas, but he did not collect it.
18th century, 1766, Cavendish submitted a research report to the Royal Society. The name of this report is Artificial Air. The experiment described that he used iron, zinc and other metals to interact with dilute sulfuric acid and dilute hydrochloric acid to produce a kind of flammable air, which was collected by drainage and gas gathering method for research.
He found that a certain amount of a certain metal reacts with a sufficient amount of various acids to produce gas, and the amount of this gas is fixed, regardless of the type and concentration of the acid.
also found that after this gas is mixed with air, if it is ignited, it will explode, and what is more interesting is that it can combine with oxygen to generate water.
So it is easy to think that water must be decomposed into two parts: oxygen and this unknown gas. But Cavendish , like Priestley , still insists that water is an element , calling this new gas with flammable air.
1782 Lavoisier repeated their experiment and decomposed water vapor with a red-hot barrel, clearly coming to the correct conclusion. Water is not an element, but a compound, consisting of hydrogen and oxygen.
Lavoisier's hydrogen burner
Until this time, human beings finally know what water is in essence. Today's topic is where water comes from, and we need to add: hydrogen and Where does oxygen come from?
2. Where did hydrogen and oxygen come from?
Now we all know that hydrogen is the number one element on the periodic table . When the universe was just formed, he was the first chemical element to appear.
When was the hydrogen atom born?
But soon after the big bang of , , the temperature of reached billions of kelvins, and all elementary particles were produced, and proton was just synthesized until the universe cooled to 3000 kelvins, and the temperature of universe was slightly lower After a while, the nucleus and electrons can be combined together.
The Big Bang Imagination
The Big Bang .7 million years later, the atom was finally born, and the hydrogen element was born.
However, it will take about 400 million years or so before gravitational has the upper hand, and star will finally form.
3, the internal mechanism of stars
There are two main types of thermonuclear reactions inside stars, one is called proton-proton reaction, and the other is difficult to call carbon nitrogen and oxygen cycle .
The proton-proton reaction is relatively well understood. It is the collision of two protons, which are hydrogen nuclei, to form helium nuclei. With it, light and energy are released.
The sun undergoes a nuclear polymerization reaction all the time.
In our sun, it is mainly this kind of reaction, but in fact the process is more complicated. The total input of
is four hydrogen nuclei, which produce one helium atom, two positrons, two neutrinos, and three photons. The sunlight that shines on us comes from this reaction.
Another carbon-nitrogen-oxygen cycle, the input and output of the reaction are the same as proton-proton.
But there are a few more intermediate links here, which are regarded as catalysts to participate in the reaction, and nitrogen and oxygen are only intermediate process products, so after a long time, they still did not appear as products. As a main sequence star, the main energy generation mechanism is the hydrogen-helium thermonuclear reaction. Only when a star evolves to a later stage with a temperature of more than 100 million Kelvin, will helium be ignited and become new fuel, which is called helium burning.
The fusion of helium nucleus and helium nucleus produces a beryllium nucleus, and the fourth element, beryllium and helium, will continue to react to form carbon. The sixth element carbon reacts with helium to generate oxygen, so the oxygen element is finally produced. Heavier nuclei are then produced, up to iron, at which point the star is not far from dying.
will eventually throw all the burned and unburned matter around in the mighty supernova explosion .
Supernova explosion
If the universe did not have the first generation of stars, there would be no system of our sun.In fact, the sun is the second or even third generation of stars.
We now know that the age of the universe is about 13.8 billion years old, and it was not until 5 billion years ago, in the Milky Way , that a huge cloud of gas and dust finally evolved into the sun and our solar system.
About 4.6 billion years ago, the emergence of what we call the eight planets gradually formed. The earliest earth was just a simple aggregate of rocks and ice cubes .
4, the birth of the earth
As the mass of the earth increases, its own gravity also increases, and then it begins to shrink. This contraction will increase the temperature of the core, and the radioactive elements inside will continue to decay, releasing a lot of heat energy.
Pristine Earth Imagination
The heat is enough to melt the entire Earth. At this time, the denser material will sink, forming the core of the , while the light material will rise, forming the part of the mantle and the crust .
It is worth noting that sky also has various meteorite smashed down from time to time.
Volcanic activity is very important at this time. Because what erupted was not just magma, but also the ice cubes glued together in the protostar disk of the previous solar system.
At this time, the earth's surface temperature is very high, exceeding the boiling point , so water can only exist in the original atmosphere in the form of water vapor.
And the meteorite that fell from the sky, if it was small, would have been burnt out in the dense atmosphere of the earth, and the water ice it carried was naturally released, entered the atmosphere, and then turned into water vapor.
If a big one hits the earth, it will also generate huge heat and release water vapor. Because the temperature is high enough, as long as a little bit of water is exposed to the earth's atmosphere or the earth's surface, it will become water vapor and stored in the in the atmosphere. The whole process of
is about 400 million years old. The temperature of the interior of the earth also gradually decreased, and the crust of the earth gradually cooled. When the temperature drops below the boiling point, the water vapor finally has a chance to condense into raindrops.
5, the first rain on earth
The first rain finally fell on the earth. However, this rain has been falling continuously for thousands of years, and finally, the most primitive ocean was formed.
A 10 million years of heavy rain
The story is not over yet. After millions of years of continuous heavy rain, the earth began to stabilize, but the sky was still not calm.
Meteorites, ice cubes, etc. in the sky existed in this piece of dust when the solar system was just born. Due to the influence of various celestial bodies, they were constantly affected by the gravity of the planet and fell into the earth. Until now, many meteorites fall into the earth in the form of meteors every year.
Some scientists estimate that these meteorites will add 200,000 tons of water to the earth every year. In other words, the water on the earth is still increasing.
Where does the water on earth come from? This is an old mystery, and he still doesn't have a definite answer to this day. But now we can actually use multiple clues to gradually put this disrupted puzzle back into a near-complete state.
The first generation of stars ended their glorious lives in superstar fashion. The stellar material was thrown into interstellar space in a violent explosion, forming the nebula , which contains various elements such as hydrogen, oxygen, carbon and nitrogen.Under the action of gravity, these substances formed the earth, including other planets. With the formation of the earth's core, mantle, and crust, rocks in a molten state of high temperature and pressure release water vapor, which remains in the atmosphere under the action of the earth's gravity. As the Earth's temperature cooled, condensation formed into water droplets and protracted heavy rains that eventually formed the primordial ocean. In addition, meteorites and comets fell into water. It has become an important supplement for liquid water on the earth, especially on the surface of the earth. Eventually, the water that is now on Earth was formed.
