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Greaves Abstract

Terrestrial Planet Bombardment and Habitability
Jane Greaves (St. Andrews, UK)
I will review the importance of bombardment by comets and asteroids in the context of the development of life. Although we have only our own life-bearing planet from which to speculate, some aspects such as a catastrophic impact at the level of destroying a planet's crust can not be good for biosystems! The Earth is now very unlikely to experience such a massive hit, as the Kuiper Belt has been largely cleared out, although ~10 km impactors every ~100 Myr may change the environment enough that new species arise. However in exo-systems, very large cometary populations are detected via the study of dusty debris, and these can persist over the entire main-sequence stellar lifetimes. I will present results on the comet populations of nearby Sun-like stars and place the Sun within this ensemble, ending with an estimate of the distance to the nearest analogue system to our own that could harbour a habitable Earth.