July 23, 2009

Comets Are Prisoners Of The Asteroid Belt

The study shows that the comets were probably captured 600 million years after the formation of the solar system, during the Late Heavy Bombardment. This extremely violent event was triggered when Saturn and Jupiter entered into orbital resonance:  Saturn's orbital period became exactly twice that of Jupiter, and the two planets passed each other more often, interacting and destabilizing everything around them. During this time, the entire architecture of the solar system was thrown into turmoil, and it was then that the comets originally located beyond the orbit of Jupiter were injected into the asteroid belt, where they reside to this day.

Before this discovery, the scientific community believed that the asteroid belt was exclusively made up of native asteroids resulting from the formation of the solar system. "This is a paradigm shift.  The asteroid belt is not just a remnant of the formation of the solar system but also the result of violent phenomena such as the Late Heavy Bombardment," explains Matthieu Gounelle of LMCM.

This model lends weight to the still controversial idea that the difference between comets and the most primitive asteroids is smaller than thought.

The study also sheds new light on the controversial origin of micrometeorites. Unlike meteorites, most of this dust is thought to come from these captured comets, which are richer in organic matter and more fragile than native asteroids.


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