Meteorites reveal the hidden history of the Solar System!

Shortly after the formation of the Solar System, the planets that make it up were much closer to the Sun than they are today. However, scientists still have little understanding of the migratory dynamics that took place early in its history. Thanks to the analysis of meteorites, a team of scientists suggests that these major migrations took place between 60 and 100 million years after the formation of the Solar System. These migrations may have even allowed the formation of the Moon…

Our Solar System was formed approximately 4.6 billion years ago. Initially, the young Sun was surrounded by a vast disk of material, called a protoplanetary disk. Over a few million years, the material in the disk begins to clump together to first form planetesimals (planetesimals). embryosembryos of planets), then entire planets. The configuration of the young Solar System was then very different from what it is today: according to the model most commonly accepted among planetologists, the gas giant planetsgas giant planets (Jupiter, SaturnSaturn, UranusUranus And NeptuneNeptune) were much closer to the Sun than they are today!

Meteorites to retrace the history of the Solar System

If this model, known as the “Nice model”, seems plausible to the majority of planetologists, we do not know precisely when these migrations took place. The question may seem incidental at first glance, but scientists attach capital importance to it: through the gravitational interactions between the different planetary bodies, these migrations have in fact generated significant movements in the different zones of the Solar System, notably bringing many of planetesimals towards the internal zone of the Solar System (where the Earth is located, among other places).

The effects of these migrations are rather well known, as evidenced by the numerous craters on the surface of the MoonMoon caused by what scientists call the Late Great Bombardment. According to the different hypotheses, this massive supply of planetesimals to the inner zone of the Solar System probably brought large quantities of volatile elements to Earth, including water, essential to life as we know it.

About 4 billion years ago, a wave of asteroids invaded the inner Solar System during a period called the Great Late Bombardment, causing massive collisions with the Moon, but also the terrestrial planets of the inner Solar System such as as Mercury, Venus, Earth and Mars. © MIT

However, it remains extremely complicated to retrace the history of the Solar System over several billion years. To build their theories, scientists run simulations to understand what sets of processes can lead to its current configuration. To better understand the dynamic history of the Solar System, a team of scientists sought to combine observations, simulations and studies of meteoritesmeteorites. They present their results in the journal Science.

They focused on a type of meteorite with a composition strongly similar to that of Earth, the chondriteschondrites enstatite. Chondrites are among the most primitive meteorites, and this similarity in composition indicates that enstatite chondrites likely formed in the vicinity of Earth. By carrying out spectroscopic studies using telescopestelescopes On the ground, scientists linked these meteorites to their source: a family of fragments in the asteroid belt known as Athor, the largest member of which is theasteroidasteroid (161) Athor. According to the team, this family likely arose from a cataclysmic collision, destroying the parent body into several fragments, the largest of which is believed to be (161) Athor. According to these data, the parent body of this family was initially formed in the vicinity of the Earth… before ending up in the asteroid beltasteroid beltbetween the orbitsorbits of Mars and JupiterJupiter.

Planetary migrations as the main factors?

To explain how Athor ended up in the asteroid belt, scientists tested different scenarios using simulations. The most likely explanation, they say, is that Athor’s migration was caused by gravitational instability that moved the giant planets into their current orbits. Analysis of meteorites has shown that this process did not occur until 60 million years after the formation of the Solar System. Previous studies of asteroids in Jupiter’s vicinity concluded that this same gravitational instability must have occurred before 100 million years after the birth of the Solar System. Conclusion: the migrations of the gas giant planets began between 60 and 100 million years after the birth of the Solar System!

This conclusion seems to agree with a number of observations: according to the most commonly accepted models, the Moon was probably formed during this period, from debris generated by the collision between the young Earth and a planetesimal the size of Mars, nicknamed TheiaTheia. Precisely determine the period of instability orbitalsorbitals can have important implications, particularly for identifying when certain features of the Solar System developed.

Depending on the hypotheses, some scientists indicate that the presence of the Moon played a major role in the appearance of life on Earth; others tend to think that the majority of the water in the earth’s oceans was brought during the Great late bombardmentGreat late bombardment. So, perhaps the appearance of life on Earth would not have been possible without the migrations of giant planets?