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Scientists find link between comet and asteroid showers & mass extinctions

Last Updated on Tuesday, 20 October 2015 11:40
Published on Tuesday, 20 October 2015 23:00

 

Mass extinctions occurring over the past 260 million years were likely caused by comet and asteroid showers, scientists conclude in a new study published in Monthly Notices of the Royal Astronomical Society.

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 the Earth.

A graph showing how the rate of cratering has changed on Earth over timeA graph showing how the rate of cratering has changed on Earth over time. The arrows indicate the dates of mass extinctions. Credit: Michael Rampino / NYU

To test their hypothesis, Rampino and Caldeira performed time-series analyses of impacts and extinctions using newly available data offering more accurate age estimates.

An artist's illustration of a major asteroid impact on EarthAn artist's illustration of a major asteroid impact on Earth. Credit: NASA

"The correlation between the formation of these impacts and extinction events over the past 260 million years is striking and suggests a cause-and-effect relationship," says Rampino.

Specifically, he and Caldeira found that six mass extinctions of life during the studied period correlate with times of enhanced impact cratering on Earth. One of the craters considered in the study is the large (180 km diameter) Chicxulub impact structure in the Yucatan, which dates to about 65 million years ago—the time of a great mass extinction that included the dinosaurs.

Moreover, they add, five out of the six largest impact craters of the last 260 million years on earth correlate with mass extinction events.

"This cosmic cycle of death and destruction has without a doubt affected the history of life on our planet," Rampino observes.

 

Media contact


James Devitt
New York University
United States
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Science contact

 

Prof Michael Rampino
New York University
United States
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Images and captions


A graph showing how the rate of cratering has changed on Earth over time. The arrows indicate the dates of mass extinctions. Credit: Michael Rampino / NYU

An artist's illustration of a major asteroid impact on Earth. Credit: NASA


Further information

The new work appears in "Periodic impact cratering and extinction events over the last 260 million years", Michael Rampino and Ken Caldeira, Monthly Notices of the Royal Astronomical Society, Oxford University Press, in press.

 


Notes for editors

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

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