One of the theories of the appearance of the moon and the appearance of water on Earth has been disproved. This made it possible to make a very accurate isotopic analysis of the oxygen contained in the rocks of the Earth and the Moon. A study by scientists from the UK, France and the United States conducting this analysis is published in the journal Science Advances.
There are several theories about how the Earth-Moon system formed and when water appeared on Earth. One of them says that, when it was still forming, another cosmic body crashed into the Earth, and the Earth and its satellite were formed from a cloud of debris, steam and dust.
This theory can be verified by comparing the isotopic composition of oxygen in the rocks of the Earth and the Moon: if it is the same, then the bodies were formed from the same "material", and it is correct. The authors of the work compared the content of oxygen isotopes in different rocks and found a very small but noticeable difference.
The content of isotopes in rocks was compared with the ratio of isotopes in earth water. The most popular theory claims that water was brought to Earth from space by meteorites in the form of ice. In this case, the isotopic composition of oxygen in water and rocks should be very different. The results showed that only 5 to 30% of the water on Earth could come from outside.