Scientists presented new details about the formation of the Earth, based on recent theory
An international research team proposes a new theory to explain the formation process of the Earth.
In this way, an answer could be given to an unknown that, despite being the subject of various studies for a long time, still does not generate consensus in the scientific community, also providing an explanation of how other rocky planets were formed.
New efforts to decipher the origin of our planet
Over the years, several hypotheses have been proposed to explain the origin of planet Earth, without overcoming the discrepancies that the various theories that have arisen arouse in the scientific community. For example, it was postulated that the collisions of the objects that later formed the Earth generated enormous amounts of heat that vaporized the light elements, leaving the planet in its current composition.
An international research team led by the Federal Technical School (ETH) Zurich and the Swiss National Center of Research Competence, PlanetSrecently proposed a new answer to the question behind the origin of the earth, based on laboratory experiments and computer simulations.
“The prevailing theory in astrophysics and cosmochemistry is that the Earth formed from chondritic asteroids. These are simple, relatively small blocks of rock and metal that formed early in the solar system.” Explain the lead author of the study, Paolo Sossi, Professor of Experimental Planetology at ETH Zurich. “The problem with this theory is that no mixture of these chondrites can explain the exact composition of the Earth, which is much poorer in light, volatile elements like hydrogen and helium than we would have expected.“, he added.
For Sossi, many of these theories, like the one mentioned above, become implausible as soon as the isotopic composition of the different elements of the Earth is measured. “All isotopes of a chemical element have the same number of protons, but different numbers of neutrons. Isotopes with fewer neutrons are lighter and therefore should be able to escape more easily. If the heating vaporization theory were correct, we would find fewer of these light isotopes on Earth today than in the original chondrites. But that’s precisely what the isotope measurements don’t show.”noted the researcher.
Sossi’s team chose to find another solution. “The dynamical models with which we simulate planet formation show that the planets in our solar system formed progressively. The small grains became kilometer-sized planetesimals over time as they accumulated more and more material through their gravitational pull.”he explained.
One of the aspects in which some debated theories coincide is the possibility that the planet originated from the collision of other “small planets”. Like chondrites, planetesimals are also small bodies of rock and metal. But unlike those chondrites themselves, these have been heated enough to differentiate into a metallic core and mantle rock. “Furthermore, planetesimals that formed in different areas around the young Sun or at different times can have very different chemical compositions.”Sossi adds. This raises the question of whether the random combination of different planetesimals actually results in a composition that matches that of Earth.
To find out, the team ran simulations in which thousands of planetesimals collided with each other, inside a primitive solar system. The models were designed in such a way that, over time, celestial bodies corresponding to the four rocky planets Mercury, Venus, Earth and Mars were reproduced. The simulations developed showed that a mixture of many different planetesimals could lead to the effective composition of the Earth. Furthermore, the composition of the Earth is even the statistically most probable result of all the simulations carried out.
“Although we suspected it, we found this result very remarkable”Sossi remembers. “Now we not only have a mechanism that better explains the formation of the Earth, but we also have a reference to explain the formation of the other rocky planets”indicated the researcher.
The mechanism used in this study could be used, for example, to predict how Mercury’s composition differs from that of the other rocky planets. Similarly, it could be used to determine how the rocky exoplanets of other stars could be composed.
“Our study shows how important it is to consider both dynamics and chemistry when trying to understand planetary formation.”Sossi commented. “I hope our findings will lead to closer collaboration between researchers in these two fields.”he added.
The findings of this research were published in an article in Nature Astronomy.
