Scientists find link between comet, asteroid showers and mass extinctions [View all]

[Agnosticsherbet]

Scientists find link between comet, asteroid showers and mass extinctions
For more than 30 years, scientists have argued about a controversial hypothesis relating to periodic mass extinctions and impact craters -- caused by comet and asteroid showers -- on Earth.

In their MNRAS paper, Michael Rampino, a New York University geologist, and Ken Caldeira, a scientist in the Carnegie Institution's Department of Global Ecology, offer new support linking the age of these craters with recurring mass extinctions of life, including the demise of the dinosaurs. Specifically, they show a cyclical pattern over the studied period, with both impacts and extinction events taking place every 26 million years.

This cycle has been linked to periodic motion of the Sun and planets through the dense mid-plane of our galaxy. Scientists have theorized that gravitational perturbations of the distant Oort comet cloud that surrounds the Sun lead to periodic comet showers in the inner solar system, where some comets strike Earth.