Nemesis comes and goes…

It has often been said that there is a peak in the extinction rate every 26 million years or so. Some put it down to the Sun having a binary companion referred to as Nemesis that flies through the solar system with this periodicity. In order to examine the claims a little more carefully, researchers have set up a graph of extinctions over the past half billion years, longer than previously studied. It shows a 27 million year repeating pattern of increases in extinction rates, which would seem to agree with the idea of Nemesis, but then again, maybe not. Within the past half a billion years, the Sun has gravitationally interacted with several other stars passing by. Yet despite the Sun, and one would assume Nemesis, getting gravitationally kicked every now and again, the orbit of the two about their common centre of mass, if Nemesis exists and is responsible for the extinctions, remains unchanged. This would be very unusual if true. The infrared space telescope WISE, which would be capable of detecting such a body has also not reported anything unusual so far.

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