How and when did water appear on Earth? Scientists are still discussing this topic, but no one has yet given an accurate and logically proven answer. To date, there are several assumptions about how liquid could form on the planet. Among them there are both completely absurd and quite logical hypotheses, but so far none of them is completely reliable.
How did water appear on Earth? Briefly about the main hypotheses
Water plays a big role in maintaining life on the planet, because it is the main internal environment of any organism. Without water, a person can, on average, last no more than three days, and the loss of 15-20% of the liquid often leads to death.
How did water appear on Earth? Hypotheses of the formation of this substance are few, and none of them has yet received truthful evidence. Nevertheless, only they can somehow explain the formation of the hydrosphere of our planet.
Hypothesis of the cosmic origin of water
A group of researchers suggested that water appeared along with numerous falling meteorites. This happened about 4.4 billion years ago, when the planet was still being born, and its surface was a dry, devastated land, over which an atmosphere had not yet formed.
When asked how water appeared on Earth, adherents of this hypothesis answer that the first molecules of this liquid brought meteorites with them. At first, these molecules existed in the form of gas and accumulated, and later, when the planet began to cool, the water turned into a liquid state and formed the Earth's hydrosphere.
Perhaps the chemical formation of water came from the primary hydrogen protons and oxygen anions, but the probability of such a reaction occurring in the thickness of celestial bodies that subsequently fell to Earth is catastrophically small.
Another hypothesis of how water appeared on Earth
It was proposed by a group of researchers led by the famous scientist V. S. Safronov. The essence of his assumption lies in the earthly origin of water, which was formed in the bowels of the planet.
Under the influence of numerous falls of meteorites, our at that time hot planet began to form a large number of volcanoes from which magma escaped. Together with it, "water vapor" was released to the surface, which caused the formation of the Earth's hydrosphere.
Despite the fact that the theory is based on the terrestrial origin of water, it cannot answer many questions. For example, howHave the rocks in the lithosphere melted so badly to cause the formation of many volcanoes? And how is water vapor formed? At first, scientists suggested that at that time there was groundwater, which escaped through the vents of volcanoes together with magma in a gaseous state.
This theory of steam formation was refuted by P. Perrault, a naturalist of the 17th century. He proved that groundwater was formed due to precipitation, and this requires the presence of an atmosphere. 4.4 billion years ago there was no atmosphere.
And the last theory
So how did water appear on Earth? Another hypothesis was able to approach the question of the formation of the planet's hydrosphere from the other side. Like the previous assumption of V. S. Safronov and his co-authors, this hypothesis is based on the terrestrial origin of water.
The difference is that, according to researchers, water molecules were formed together with the protoplanetary disk of the Earth, i.e. during the formation of the planet itself. Deuterium and oxygen served as the source of water molecules.
Deuterium is ordinary hydrogen with one neutron in the nucleus. This heavy isotope was found in ancient bas alt samples found in the Arctic on Baffin Island (1985). These rocks are formed from particles of protoplanetary dust that were not affected during the formation of the planet. According to the researchers, the chemical nature of deuterium would not allow the isotope to formoff planet.
This is how water appeared on Earth according to these scientists. If their data is correct, about 20% of the modern world ocean was formed during the formation of the protoplanetary disk. Today, researchers are looking for a way to prove that most of the world's oceans, as well as atmospheric water vapor and groundwater, formed from "protoplanetary" water.
