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The Solar System and The Planetesimals Accretion. “The Sofronov’s Theory” By Massimo Auci. The formation of the Solar System from a cloud of gas and dust grains: “ the primordial nebulae ”.
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The Solar System and The Planetesimals Accretion “The Sofronov’s Theory” By Massimo Auci
The formation of the Solar System from a cloud of gas and dust grains: “the primordial nebulae”
During the disk phase (100 millions years), the material that has not been incorporated in the central protostar rotates around it.The grains of dust grow in size very rapidly (this phenomenon being called accretion).
After a relatively short period (100,000 years) the grains will have grown into objects of some km of diameters called planetesimals.
At this point of the evolution, a period of heavy bombardment is thought to have taken place (about from 4 to 3.5 millions years ago). Most of the craters today seen on the Moon and on satellites without atmosphere are due to that period.
The asteroids today inhabiting the main belt, can be seen as the remnants of a never-born planet.
The word NEO stands for Near Earth Object, meaning a minor body of the solar system. A first classification of NEOs is: • NEC (Near earth comets) • NEAs, Near Earth Asteroids constituting the vast majority of NEOs, further divided into three main families, depending on the features of their orbits. In particular they are classified in three groups (Amor, Apollo and Atens) according to their perihelion and aphelion distances and their semi major axes.