The science of Armageddon.

Over the past decade the risk of asteroids and comets colliding with Earth has emerged as one of the most significant natural hazards faced by the terrestrial biosphere. Ongoing studies of comets and asteroids, their distribution and dynamics, the cratering record on Earth and elsewhere in the solar system, all point to a long-term risk whose magnitude exceeds many others that generate substantial international concern. The origins and composition of the solar system, and particularly potentially hazardous asteroids and comets are described with references to meteorites and impact structures. Additionally, the nature and extent of the NEO (Near-Earth Objects) impact hazard, and the measures that are required to reduce the risk are considered. [ABSTRACT FROM AUTHOR]