Asteroids don’t hit Earth at regular intervals, as was previously thought

Asteroids don’t hit Earth at regular intervals, as was previously thought

Do mass extinctions, like the fall of the dinosaurs, and the formation of large impact craters on Earth occur together at regular intervals?

“This question has been under discussion for more than thirty years now,” says Matthias Meier from ETH Zurich’s Institute of Geochemistry and Petrology.

As late as 2015, US researchers indicated that impact craters were formed on Earth around every 26 million years. “We have determined, however, that asteroids don’t hit the Earth at periodic intervals,” says Meier, refuting the popular hypothesis.

In the past, researchers have even postulated the existence of a companion star to the Sun.

This supposed dim dwarf star, named Nemesis after the Greek goddess of revenge, was believed to draw near to the Sun every 26 million years and cause asteroids to bombard Earth.

This would next occur in around 10 million years. Nemesis, however, has never been found.

False data corrected

Today, we know of around 190 impact craters on Earth, with diameters ranging from a few meters to more than 100 kilometers.

They range from just a few years to billions of years old. Matthias Meier and his former doctoral student Sanna Holm-Alwmark at Lund University restricted their analysis to craters formed within the last 500 million years, since the emergence of the first complex life forms.

Holm-Alwmark then discovered that some of the dates used in previous studies were false, and have now been corrected. She arrived at a list of 22 craters whose exact age is known to within one percent.

Meier then analysed these impacts using circular spectral analysis (CSA). The timeline of events was represented in a circle with a particular range – in this case, 26 million years.

If events repeated themselves regularly within this timespan, the points would have arranged themselves in a particular area of the circle.

In their work, which was published in the British journal Monthly Notices of the Royal Astronomical Society, Meier and Holm-Alwmark showed that there was no such accumulation.

Like Knowridge Science Report on Facebook. 

News source: ETH Zurich. The content is edited for length and style purposes.
Figure legend: This image is for illustrative purposes only.