The embryos of Earth and Mars were so hot that their "atmosphere", which consisted of silicon and metal vapors, constantly escaped into space, depriving future planets of about 40% of their mass, scientists say in articles published in the journal Nature.
“In the past, we certainly knew that the process of planetary formation was particularly turbulent, and that the Earth and other planets have a unique chemical and isotopic composition compared to asteroids, but did not realize that these things were related. It turned out that the collisions of planetary embryos and their evaporation into space greatly influenced the composition of the Earth and Mars,”explains Remco Hin from the University of Bristol (UK).
Today, scientists have almost no doubt that the planets begin their birth inside a flat gas-dust disk filled with small dust particles and dense clouds of gas, and their formation ends in a series of collisions of planetisimals - the "embryos" of planets the size of West or Ceres, as well as large comets and asteroids.
On the other hand, we do not yet know anything about what these embryos of planets looked like and how exactly the collisions between them took place. Some scientists believe that planetisimals looked like giant hot spheres of molten magma, while others believe that they were more like giant balls of semi-liquid mud.
These disagreements, as Hin notes, are largely due to the fact that even the most ancient and "pure" rocks of Mars, Earth and the Moon radically differ in their chemical and isotopic composition from the primary matter of the solar system, fragments of which periodically fall to the Earth in the form chondrite asteroids. So far, scientists cannot explain these discrepancies, which prevents the disclosure of the history of the formation of the Earth and planets outside the solar system.
Hin and his colleagues, as well as another group of scientists from Oxford, came close to answering this question by creating the first detailed computer "simulator" of the early solar system, taking into account all possible physical processes that influenced the formation and collision of planetisimals.
These calculations revealed one interesting effect that scientists had not previously thought about. It turned out that relatively small planetary embryos, inferior in size to Mars, will have an extremely unstable "atmosphere" consisting of vaporous silicon, sodium and other metals and other chemical elements.
This atmosphere will be constantly warmed up by the falls of other celestial bodies on similar "embryos", and at the same time it will constantly escape into space, since the attraction of the planetisimals will be too weak to keep such hot "air" at its surface.
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Here the laws of physics come into play, postulating that the less the mass of this or that element or its isotope, the easier it can "escape" from the planet's atmosphere. Thanks to this, magnesium, silicon and many other relatively light substances evaporated most rapidly from the atmosphere of the future Earth and Mars.
Scientists estimate that both planets could have lost about 40% of their mass and lost most of the volatiles and light isotopes of magnesium and other metals, which are present in large quantities in the matter of asteroids and comets. In a similar way, scientists believe, other planets outside the solar system may form, and observations of them will help test whether this is actually so and confirm or refute the hypothesis of British geologists.
