The well was filled. Where did water come from on Earth? How many hypotheses for the appearance of water on Earth are there? When the first ones appear in the water
There are six hypotheses for the appearance of water on the globe.
First hypothesis comes from the “hot” origin of the Earth. It is believed that the Earth was once a molten ball of fire, which, radiating heat into space, gradually cooled. The primordial crust appeared, chemical compounds of elements arose, and among them the compound of hydrogen and oxygen, or, more simply, water.
The space around the Earth became increasingly filled with gases that continuously erupted from cracks in the cooling crust. As the vapor cooled, it formed a cloud cover that tightly enveloped our planet. When the temperature in the gas envelope dropped so much that the moisture contained in the clouds turned into water, the first rains fell. Millennium after millennium the rains fell. They became the source of water that gradually filled the oceanic depressions and formed the World Ocean.
Second hypothesis comes from the “cold” origin of the Earth with its subsequent heating. The heating caused volcanic activity. Lava erupted by volcanoes carried water vapor to the surface of the planet. Some of the vapor, condensing, filled the oceanic depressions, and some formed the atmosphere. As has now been confirmed, the main arena of volcanic activity in the early stages of the Earth's evolution was indeed the bottom of modern oceans.
According to this hypothesis, water was already contained in the primary matter from which our Earth was formed. Confirmation of this possibility is the presence of water in meteorites falling to Earth.
Third hypothesis also comes from the “cold” origin of the Earth with its subsequent heating. In the Earth's mantle at depths of 50–70 km, water vapor began to arise from hydrogen and oxygen ions. However, the high temperature of the mantle did not allow it to enter into chemical compounds with the mantle matter.
Under the influence of pressure, steam was squeezed into the upper layers of the mantle, and then into the Earth's crust. In the crust, lower temperatures stimulated chemical reactions between minerals and water, as a result of loosening the rocks, cracks and voids formed, which were immediately filled with free water. Under the influence of water pressure, the cracks split, turned into faults, and water rushed through them to the surface. This is how the primary oceans arose.
The above hypothesis is supported by a sharp increase in the speed of seismic waves at a depth of 15–20 km, i.e., exactly where the boundary of the supposed interface between granite and the brine surface should lie, the boundary of a sharp change in the physical and chemical properties of the substance.
This hypothesis is also confirmed by the so-called continental drift. The granite masses of the continents are moving. They “float”, although their speed of movement is only a few centimeters per century.
Fourth hypothesis belongs to the English astrophysicist Hoyle and was published relatively recently, in 1972. It is a consequence of the hypothesis of the origin of the Solar system. The condensation of the protoplanetary cloud surrounding the proto-Sun proceeded unequally at different distances from the Sun. The farther from it, the lower the temperature of the cloud. Closer to the Sun, say, metals could condense as more refractory substances. And where the orbits of Uranus, Neptune and Pluto pass, according to Hoyle’s calculations, the temperature was approximately 350 K, which is already sufficient for the condensation of water vapor. It is this circumstance that can explain the “watery” nature of Uranus, Neptune and Pluto, formed in the process of merging particles of ice and snow. The “water” nature of these planets is confirmed by the latest astronomical observations.
Hoyle's calculations confirm the possibility of the formation of Earth's oceans from freezing rain, which took only a few million years.
Fifth hypothesis, like the fourth, assumes the cosmic origin of water, but from other sources. The fact is that a shower of electrically charged particles is continuously falling onto the Earth from the depths of space. And among these particles, a fair proportion are protons - the nuclei of hydrogen atoms. Penetrating the upper layers of the atmosphere, protons capture electrons and turn into hydrogen atoms, which immediately react with atmospheric oxygen. Water molecules are formed. Calculations have shown that a cosmic source of this kind is capable of producing almost 1.5 tons of water per year, and this water reaches the earth's surface in the form of precipitation.
Sixth hypothesis. As scientists have established, approximately 250 million years ago there was a single continent on Earth. Then, for unknown reasons, it cracked, and its parts began to creep apart, “floating” away from each other.
Evidence of the existence of a once single continent is not only the similarity of coastlines, but also the similarity of flora and fauna, the similarity of the geological structures of the coasts.
Research in recent years has confirmed that the continents are “floating”, the distance between them is continuously increasing. The movement of continents is brilliantly explained by the expanding Earth hypothesis. The hypothesis states: initially the Earth had a radius half as large as it is now. The continents, then fused together, encircled the planet.
There were no oceans. And then, at the border of the Proterozoic and Mesozoic (250–300 million years ago), the Earth began to expand. The single continent gave way to cracks, which, when filled with water, turned into oceans.
However, as the dust cloud compacted, its gravitational compression occurred, and the pressure inside the proto-Earth increased. Accordingly, the degree of hydrogen absorption by metals of the iron group also increased. Compression generated the antipode of pressure - heating. And since the central regions of the formed planet were subjected to the greatest compression, the temperature there also increased more rapidly.
And at some stage of heating, when the temperature in the Earth’s core reached a certain critical value (the transition of quantitative growth to a new qualitative state!), the reverse process began - the release of hydrogen from metals.
Thus, the degassing of hydrogen was accompanied by the expansion of the Earth. Meanwhile, hydrogen, penetrating the enormous thickness of the planet, captured oxygen atoms along the way, and water vapor was already escaping to its surface. Condensing, the water filled the cracks in the crust. Oceans gradually formed.
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There are several fundamentally different assumptions that have divided scientific minds into two camps: some are supporters of the meteorite or “cold” origin of the earth, while others, on the contrary, prove the “hot” origin of the planet. The first believe that the Earth was originally a large, solid, cold meteorite, while the second argue that the planet was hot and extremely dry. The only undeniable fact is that such a vital element as water appeared on Earth at the stage of formation of the blue planet, that is, long before.
The hypothesis of a “cold” origin of the planet
According to the hypothesis of a “cold” origin, the globe was cold at the beginning of its existence. Subsequently, due to the decay, the planet's interior began to warm up, which became the cause of volcanic activity. The erupted lava brought various gases and water vapor to the surface. Subsequently, with the gradual cooling of the atmosphere, some of the water vapor condensed, which led to a huge amount of precipitation. Continuous rains over thousands of years at the initial stage of the formation of the planet became a source of water that filled the oceanic depressions and formed the World Ocean.
The hypothesis of a “hot” origin of the planet
Most scientists who hypothesize the “hot” origin of the Earth do not in any way connect the appearance of water on the planet with. Scientists have suggested that the structure of planet Earth initially contained hydrogen layers, which subsequently entered into a chemical reaction with oxygen that was in the earth’s mantle at the initial stage of formation. The result of this interaction was the appearance of a huge amount of water on the planet.
However, some scientists do not exclude the participation of asteroids and comets in the creation of water on a vast territory of the earth. They suggest that it was thanks to the continuous attacks from large comets and asteroids, which carried reserves of water in the form of liquid, ice and steam, that huge expanses of water appeared, filling most of planet Earth.
At all times, people have wanted to know how planet Earth was formed. Despite the fact that there are many hypotheses, the question of the origin of water on our planet still remains open.
MOSCOW, January 12 - RIA Novosti. The oldest rocks of the Earth from a Canadian island in the Arctic told scientists that the water of our planet existed on its surface originally, and was not brought by comets or asteroids, according to an article published in the journal Science.
“We found that the water molecules in the samples of these rocks contained few atoms of deuterium, heavy hydrogen. This suggests that it came to Earth not after it had formed and cooled, but along with the dust from which it was formed our planet. Most of the water in this dust evaporated, but there was enough leftover to form the Earth's oceans," said Lydia Hallis from the University of Glasgow (Scotland).
Today, planetary scientists believe that the Earth’s waters are of “cosmic” origin. Their source, according to half of them, is comets, while other astronomers believe that the water reserves of our planet were “brought” to it by asteroids.
Hallis and her colleagues showed that our planet's oceans may in fact be filled with its own water by studying samples of Earth's oldest basalts found in Baffin Land, Canada, in 1985.
These fragments of the Earth's mantle, as the geologist explains, contain so-called inclusions - small balls of crystals of refractory rocks that formed at the dawn of the solar system, about 4.5-4.4 billion years ago. Due to the fact that they never left the bowels of the Earth and did not mix with the rocks of the earth’s crust, they contain the primary matter of our planet.
Hallis's group decided to take advantage of this fact to study the isotopic composition of the water contained in these inclusions and compare it with the values in fractions of hydrogen isotopes that are typical for the waters of the Earth today and for asteroids and comets.
Scientists: Jupiter could destroy “super-Earths” in the young solar systemOur Solar System may have contained one or more large Earth-like planets in the early stages of its formation, which were later absorbed by the Sun as a result of the migrations of Jupiter.As it turned out, the primary rocks of the Earth contained unusually little deuterium, heavy hydrogen, noticeably less than is contained in the waters of modern oceans and in the matter of small celestial bodies. This suggests that the source of water was the primary matter of the gas-dust disk from which the Earth and all other inhabitants of the Solar System were born.
Why is this so? Initially, as Hallis explains, the primordial matter of the solar system contained very little deuterium. Deuterium is heavier than “ordinary” hydrogen, and therefore its atoms evaporate into space from the surface of the Earth or other celestial bodies much more slowly than simple protons. Therefore, the more time water spends in open space, the less deuterium it will contain. This explains why the small amount of deuterium in water in samples of these rocks indicates the “terrestrial” origin of water in the oceans of our planet.
Today, very few scientists believe that water and most of the gases in the Earth’s atmosphere could have arisen on our planet “independently.” This is explained by the fact that the Earth is located in the so-called hot part of the protoplanetary disk, where water ice and other frozen volatile substances were gradually destroyed under the influence of ultraviolet and other rays of the newborn Sun.
On the other hand, in recent years, planetary scientists have found a lot of evidence and theoretical evidence in favor of the fact that the Earth and some other Earth-like planets of the solar system could have formed in a more distant and cold part of the protoplanetary disk, and then were “driven” from their place into modern orbits Jupiter and Saturn. The discovery by Hallis and her colleagues may be another argument in favor of this “migration” theory.
Astronomy scientists from the French University of Bordeaux - Sean Raymond - and the Brazilian State University of Sao Paulo Julio de Mesquita Filho - Andre Isidoro - described the probable mechanism for the appearance of water on our planet. Scientists published their research in the publication Icarus. Raymond also wrote about the study on his blog.
Scientists believe that the water on our planet and the celestial bodies of the asteroid belt between the orbits of Jupiter and Mars have a common origin, which is primarily associated with the formation of gas giants in the Solar System.
Three quarters of the earth's surface is covered by oceans, but at the same time, the water that is on the surface occupies only one four thousandth of the total mass of the Earth. Water is present in both the core and mantle of the planet. Scientists do not know how much there is, but they estimate that it is about ten times more than on the surface.
Thus, experts say, there is little water on Earth, and there is also some on Mercury, the Moon, Mars and Venus. There was probably more water on Mars and Venus before. The main reservoir of water within Jupiter's orbit is the asteroid belt.
The core of the inner part of the belt (about 2-2.3 astronomical units from the Sun) is made up of rocky class S asteroids, and the outer part is dominated by carbonaceous asteroids of class C. Carbonaceous asteroids contain more water than rocky asteroids (water in class C asteroids is about 10 percent).
According to scientists, the origin of water can be determined by isotope analysis of hydrogen, which is contained in the water of various kinds of celestial objects. In addition to hydrogen with a nucleus of one proton (protium), hydrogen with a nucleus with a neutron and a proton (deuterium) and very rarely hydrogen with a nucleus with two neutrons and a proton (tritium) are sometimes found in nature.
Isotope analysis can reveal some features. The Sun and gas giants are characterized by a ratio of tritium to deuterium, which is several orders of magnitude lower than that of our planet. At the same time, class C asteroids have almost the same indicator as the Earth. Thus, this may indicate a common origin for the water.
The ratio of protium to deuterium in comets in the Oort cloud is approximately twice that of our planet. Within the orbit of Jupiter, there are three comets that have similar parameters, but there is also a comet with this indicator 3.5 times higher. This may indicate that the water on these comets may have a different origin and only part of this water was formed in the same way as on our planet.
Planet formation occurs in giant disks of gas and dust around young stars. Since the closer to the Sun, the hotter it is, planets that are rich in iron and silicon are formed there. The farther from the star, the colder it is, so celestial bodies there can also arise from water vapor. Our planet was formed in that part of the gas-dust disk where rocky celestial bodies devoid of water arose. Thus, water probably entered the Earth from outside.
At the same time, there are many differences between S and C class asteroids, so they could not have formed close to each other. In addition, the boundary beyond which the formation of icy celestial bodies occurred periodically moved during the evolution of the Solar System, and the planet Jupiter played a major role in this process.
According to scientists, the process of formation of Saturn and Jupiter occurred in several stages. Initially, these were solid celestial objects, the weight of which was several times greater than the mass of the modern Earth. Later they began to capture gas from the protoplanetary disk. This led to a sharp increase in the size and mass of the planets, and the giants began to clear a place for themselves in the protoplanetary disk.
Saturn and Jupiter were surrounded by small planetesimals - the predecessors of protoplanets. As Saturn and Jupiter grew, their orbits stretched, crossed the inner zone of the Solar System and moved away from the Sun. At the same time, the giants attracted gas from the protoplanetary disk, as a result of which, according to the simulation, the orbits of the planetesimals were adjusted by Jupiters and moved to where the asteroid belt is currently located.
The formation of Saturn occurred later than Jupiter, and its emergence provoked a new migration of planetesimals, but it was insignificant. Based on this, the researchers suggested that in the belt of the limits of the orbits of the giants, class C asteroids appeared after the completion of the formation of Saturn and Jupiter. In this case, part of the planetesimals could move to the orbit of Neptune.
According to researchers' assumptions, water came to Earth during the formation of the asteroid belt due to planetesimals of a certain type (more precisely, class C asteroids) with unstable and very elongated orbits that crossed the Earth's trajectory. And the main confirmation of this is hydrogen isotope analysis.
With the formation of Saturn and Jupiter and the disappearance of the protoplanetary disk, the delivery of water to our planet was almost completed. Thus, the hypothesis that explains the small size of the Red Planet by moving deeper into the solar system of Jupiter is associated with the mechanism of enrichment of the Earth with water. The appearance of water in the inner Solar System (both in the asteroid belt and on rocky planets) turns out to be just a side effect of the growth of the gas giants Saturn and Jupiter.
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Water is a binary inorganic compound whose molecule consists of two hydrogen atoms and one oxygen atom. Under normal conditions, it is a colorless liquid (in small volumes), taste and odor. Water exists under Earth's conditions in three states of aggregation, as well as on hydrophilic surfaces - in the form of liquid crystals
Since ancient times, water has been treated with respect, considering it one of the Elements of nature - air, water, earth and fire. The ancient Greek philosopher and mathematician Thales of Miletus (624 - 546 BC) argued that water is the most important of them: "... everything from water and into water decomposes." Organic life requires water and it is believed that it served as the place of its origin. About 71% of the earth's surface is covered with water - 361.13 million square kilometers. The oceans account for 96.5% of all water, !.7% is groundwater, 1.7% is glaciers and ice caps of Antarctica and Greenland. A little is represented by rivers, lakes and swamps, 0.001% is in the clouds. Most of the earth's water is salty. The share of fresh water is approximately 2.5%, with most of it contained in glaciers and groundwater. Less than 0.3% of all fresh water in rivers, lakes and the atmosphere. There are several theories about the possible appearance of water on our planet. Conventionally, they can be divided into two groups - the terrestrial origin of water and the cosmic origin of water.
Ocean inside the planet. Terrestrial origin of water
One of the hypotheses of terrestrial origin considers the appearance of water, among other chemical elements, during the hot phase of the formation of the planet. Water vapor, along with other resulting gases, erupted from cracks in the cooling crust, forming the planet's cloud cover. When the temperature dropped, condensation began, rain began to pour, filling natural depressions and depressions, forming reservoirs.
Another hypothesis speaks of the heating of the planet as a result of intense volcanic activity during the youth of the Earth. As we now know, the bottom of modern oceans was the site of ancient volcanoes. In the Earth's mantle at a depth of 50 km - 70 km, water vapor began to arise from hydrogen and oxygen ions. However, the high temperature of the mantle did not allow it to enter into chemical compounds with matter. Under pressure, steam was squeezed into the upper layers of the mantle and into the crust. In the crust, the temperature is lower and chemical reactions between minerals and water begin. The result of this process was the loosening of rocks, the formation of cracks and voids. They filled with water. The pressure turned them into cracks and through them water rushed to the surface. Hot water in the bark easily dissolved alkalis and acids. This mixture corroded everything around it, turning into a kind of brine that gave the seas a salinity. The brine was spreading under the granite base of the continents. It could not penetrate granite; the porous structure retained the mixture, blocking the path of water. If this is so, then under the continents at a depth of 12 km - 20 km there are oceans of compressed water saturated with salts and metals. It is possible that such oceans are also located under the basalt ocean floor. This hypothesis is supported by the inexplicable sharp increase in the speed of seismic waves, which was recorded at a depth of the same 12 km - 20 km, where the supposed granite-brine interface, the boundary of a sharp change in the physico-chemical properties of the substance, should be located. Continental drift indirectly supports this hypothesis - perhaps the brine oceans play the role of a lubricant along which the continents slide.
Another hypothesis for the terrestrial origin of water is that water is formed as a result of the release of hydrogen as a result of the breakdown of metal-hydrogen compounds, that is, the restoration of metal structures in the mantle and core of the Earth. This process causes the expansion of the Earth, which is actually recorded - so Moscow and St. Petersburg are floating east at a speed of 10 cm per year, and Hamburg (in the center of Europe) remains in place, that is, Europe is expanding. The released hydrogen captures oxygen atoms along the way from the depths and water vapor breaks out to the surface. As water condenses, it fills cracks in the crust, forming oceans.
Water was delivered from space
And the following hypotheses suggest the cosmic origin of water. One claims that water was brought to the planet by comets, asteroids or meteorite bodies. Indeed, meteorites contain up to 0.5% water. Few? Only at first glance. However, if the Earth was formed from similar cosmic debris (impact and subsequent connection), then with a total mass of six by ten to the twenty-first power of tons, it should contain three by ten to the nineteenth power of water. The total mass of water on the planet, according to modern data, is about fourteen to ten to the ninth power tons. It turns out that the Earth is saturated with water from the center to the surface like a sponge.
Another space hypothesis claims that it was not the water itself that was delivered from space, but its components. A shower of charged particles continuously rains down on the Earth. Among them, a significant proportion are protons - the nuclei of the hydrogen atom. In the upper layers of the atmosphere, capturing electrons, they turn into hydrogen. Which reacts with oxygen in the atmosphere and forms a water molecule. One and a half tons of water per year. The process did not start yesterday. Perhaps he was walking at a different speed before? So that water flooded the entire surface of the planet, reaching the mountain peaks? And then she went into the depths, leaving the oceans...
There are many hypotheses, it is difficult to confirm them. The incoming data from recent studies are often contradictory and it is still very difficult to come to a consensus. Here are some conclusions of modern experts. Professor Vasily Ivanovich Ferronsky, chief researcher at the Institute of Water Problems of the Russian Academy of Sciences, studied the oxygen isotope content in ocean waters and in ancient rocks of the Earth - granites and basalts. The experiment showed that the rocks contain significantly more of this isotope. This allows us to assert that water could not have been formed due to its release from the bowels of the Earth.
Comet Hartley 2's water is identical to Earth's
Data from the Rosetta space module, which studies the nucleus of comet Churyumov-Gerasimenko (67P), indicate that the deuterium content in cometary vapor significantly exceeds the parameters of terrestrial water. This means that the earth’s water is not from comets. However, not everything is clear here. Yes, in comets from the Oort cloud (at the edge of the solar system) the water does not coincide in composition with that on Earth, but there is also a family from the Kuiper belt (between Neptune and Uranus). And observations using the Herschel orbital telescope indicate that the water contained in comet Hartley-2 (Kuiper belt) is completely identical to that on Earth in isotopic composition. This means that Earth's water can be cometary...
Astronomers report that they have discovered water in protoplanetary disks. The most interesting part of the disk is the middle part, where the water can be warm. Such a supply of warm liquid water in the future could become the beginning of the oceans and helps explain the emergence of water on Earth without the participation of asteroids and comets. By the way, about asteroids. One of them, located in the main belt, 24 Thermis, is covered with a thick layer of frost. Asteroids of this type could well deliver it to Earth. It turns out that it is too early to discount asteroids.
The oldest water in the Universe has been discovered at a distance of 11 billion light years from Earth. Astronomers believe that this is a common conjunction not only in the present, but also in the early Universe, no more than 2 billion years old.
Scientists in Japan believe that the early Earth had a dense hydrogen atmosphere, which interacted with oxygen in the planet's structure to form water. On the other hand, Japanese geologists talk about entire layers of hydrogen in the earth’s structure, which interacted with oxygen from the mantle... Yeah... In a word, “... dark is the water in the clouds of air” (Old Testament, Psalter, ps. 17 , art. 12).
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