Nemesis Theory and Search

The "Nemesis Theory" was an outgrowth of the discovery of Alvarez et al., that the impact of a large (10 km diameter) comet or asteroid was responsible for the great mass extinction that took place 65 million years ago.

Studies of the fossil record by Dave Raup and Jack Sepkoski shows that this was not an isolated event, but one of several mass extinctions that appear to occur on a regular 26 million year cycle. Their original paper analyzed marine fossil families, and was published in the Proceedings of the National Academy of Science USA, vol 81, pages 801-805 (1984). Additional analysis in terms of fossil genera confirmed their conclusions; see, for example, J. Sepkoski, J. Geological Society, London, vol 146, pp 7-19 (1989).

According to the Nemesis model, a companion star orbiting the Sun perturbs the Oort comet cloud every 26 Myr causing comet showers in the inner solar system. One or more of these comets strike the Earth causing a mass extinction. We are currently using the automated telescope at Leuschner Observatory to search for Nemesis.

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