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The migration of the planets


New research on the objects that orbit in the main asteroid belt shows a wide variability in their composition and size, a sign of the great planetary upheaval during the first billion years of the solar system. The study is published in Nature.

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This artist’s conception shows how families of asteroids are created. Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun.

Source: www.jpl.nasa.gov

The turbulent history of the chaotic evolution of the solar system has left tell-tale tracks in the asteroid belt between Mars and Jupiter, according to a new study, published in Nature, in which Francesca DeMeo (Harvard-Smithsonian Center for Astrophysics) and Benoit Carry from the Paris Observatory have mapped the composition and distribution of main belt asteroids.

The incredible variability in the size and composition of the asteroid belt is not a surprise. For the past ten years, several studies have disproved the previous hypothesis that they wanted the celestial objects in the main belt that will be formed on site and that they were the remains of a planet never born, failing because of the strong gravity of nearby Jupiter.

The wide spectrum that emerges from the mapping of asteroids implies instead that their current spatial distribution is the result of the migration of the planets during the first billion years of the solar system. A period of great agitation, during which, according to modern physics models, the giant planets have gone migrating to the inner solar system and outside before finding peace and settle in present orbits. During these upheavals have shaken the planets and asteroids moved “like flakes in a glass ball with snow”, said DeMeo .

An exemplary case is the case of planet Jupiter. The distribution and composition of asteroids in the range suggests in fact, that during its migration, the gas giant has approached the Sun to reach the orbit of Mars today. Doing so it would wipe out the asteroid belt almost completely, leaving only one-tenth of one percent of its original population. Then reversing the route to the outer solar system Jupiter would have repopulated the belt with new material. The main asteroid belt contains, nowadays, in essence, samples from the entire solar system.

DeMeo and Carry browse in their article, the recent developments in the discovery and cataloged almost entirely the rocks of the belt. But the mapping of asteroids also suggests some new and interesting line of inquiry: such as the development of systems for extrasolar planets, in connection with the history of the Earth. The water of our oceans could, in fact, just come from asteroid impacts occurred during the period of strong shaking of the planets’ migration. If it were like this, there would be another condition to be placed on the suitability of exoplanets, or just the fortuitous impact of a sufficiently large number of asteroids, and Earth-like worlds could then, be rarer than we think.

Despite all the studies, analyzes and mappings, much knowledge remains to be discovered about these celestial bodies and their internal structure. Waiting to send the first man on an asteroid, NASA look with high expectations approaching the probe Dawn to Ceres, the most massive asteroid belt, where, according to a recent study, there should be at least a bit of water .

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