Asteroid Showers on Earth after Family Breakup Events

Abstract The fate of a fraction of the near-Earth asteroid (NEA) population is to collide with terrestrial planets. Collisional events in the main asteroid belt provide a source of NEAs. We provide the first quantitative evaluation of the numbers of impactors produced in different size ranges by some events which produced recognized asteroid families in the main belt. Following certain family-forming events large enhancements in the rate of Earth impacts likely occurred, in the form of “asteroid showers” lasting 2–30 Myr, capable of influencing the Earth's biosphere. Such a shower could also be responsible of the hypothesized “lunar cataclysm” 4 Gyr ago. Because the number of NEAs is strongly affected by such events, the NEA population cannot always remain in a steady state.

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