March 7 (UPI) -- New analysis of Earth's myriad craters turned up no evidence of an impact pattern. Earth is bombarded at random, the research shows.
Some astronomers suggest the sun possesses a companion star, which makes its closest approach to the solar system every 26 million years, triggering a barrage of asteroids. But the sibling star, named Nemesis, has never been found, and the latest analysis suggests there is no order to Earth's impacts.
Scientists are aware of roughly 190 impact craters on Earth. Of the 190, scientists from ETH Zurich and Lund University identified 22 for which the impact dates are calculated with 99 percent certainty. Researchers used a data analysis method called circular spectral analysis to look for patterns among the impacts.
The data analysis suggests some crater clusters may be explained by periodic astronomical phenomena, but across larger timescales asteroid impacts are largely random.
"Some of these craters could have been formed by the collision of an asteroid accompanied by a moon," Matthias Meier, a researcher at ETH Zurich's Institute of Geochemistry and Petrology, said in a news release. "But in other cases, the impact sites are too far away from each other for this to be the explanation."
Meier and his colleagues detailed their findings in the journal Monthly Notices of the Royal Astronomical Society. The newest results contradict the conclusions of a similar study published by Meier and company in 2015. Because the involved data sets are relatively small, the presence of just a few craters with the same age can trick statistical models.
"Our work has shown that just a few of these so-called impact clusters are enough to suggest a semblance of periodicity," Meier said.