Most people are aware of the Nemesis hypothesis, but for those who haven’t heard of it or need their memories refreshed. The Nemesis Theory in short proposes that our Sun may have an undetected companion star in highly elliptical orbit that disturbs the comets in the Oort cloud approximately every 26 million years, causing an increase in the number of impact events on Earth causing mass extinctions on Earth. Over the years this idea has also become known as the “Death Star” hypothesis.
This Death Star hypothesis came about because of a discovery first made by paleontologists David Raup and Jack Sepkoski, published in a 1984 paper claiming that they had identified a 26 million year cycle of mass extinctions occurring over the last 250 million years. They identified 12 extinction events that statistical averaged out to a time interval between events of 26 million years.
Newer data and improved dating going back to 500 million years appears to support the original discovery of mass extinctions occurring about every 26 million years. The newer information adds about a million years to the interval between extinction events, making them closer to 27 million years between events.