Extinction of species by periodic comet showers
@article{Davis1984ExtinctionOS, title={Extinction of species by periodic comet showers}, author={Marc Davis and Piet Hut and Richard A. Muller}, journal={Nature}, year={1984}, volume={308}, pages={715-717} }
A 26-Myr periodicity has recently been seen in the fossil record of extinction in the geological past1. At least two of these extinctions are known to be associated with the impact on the Earth of a comet or asteroid with a diameter of a few kilometres (refs 2, 3). We propose that the periodic events are triggered by an unseen companion to the Sun, travelling in a moderately eccentric orbit, which at its closest approach (perihelion) passes through the ‘Oort cloud’ of comets which surrounds the…
229 Citations
Orbital stability of the unseen solar companion linked to periodic extinction events
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Recent suggestions of astronomical causes for the closely periodic extinction events in the geological record1 and the possible periodicities in the cratering record2 have involved two basic ideas.…
How stable is an astronomical clock that can trigger mass extinctions on Earth?
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Dynamical constraints on the mass and perihelion distance of Nemesis and the stability of its orbit
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- 1984
Recent evidence has indicated that the impact of a comet or asteroid may have been responsible for mass extinction at the ends of both the Cretaceous1 and the Eocene2–4. Quantitative analysis by Raup…
Terrestrial impactors at geological boundary events: comets or asteroids?
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Evidence has been presented1,2 for a 26–28-Myr periodicity in both the terrestrial extinction record and the age of large well-dated impact craters on the Earth. A cometary source controlled by…
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Cometary impacts, molecular clouds, and the motion of the Sun perpendicular to the galactic plane
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- 1985
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Terrestrial catastrophism—Nemesis or Galaxy?
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The ∼30 Myr periodicity associated with the Sun's motion through the central plane has been linked to geomagnetic reversals1,2, biological extinctions3 and crater ages4–6. This periodicity is…
Statistical and Evolutionary Aspects of Cometary Orbits
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- 1989
The observed frequency of passages of Earth-crossing long-period (LP) comets (P > 200 yr) is about three per year for comets brighter than absolute magnitude H10 ~ 10.5. About one out of six LP…
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