A mysterious, hidden planet that could be sitting on the edge of our solar system might be linked with periodic extinctions on Earth, according to a researcher.

The unconfirmed planet might trigger comet showers, bringing huge extinction events, according to a new paper by Daniel Whitmire, a retired astrophysics professor. The paper links the periodic extinction events that happen on Earth — which can be seen in the fossil record to wipe out huge parts of life on Earth about every 27 million years — with the unknown Planet 9.

Planet 9 has been said by some to exist for years. But in recent months two scientists claim to have found strong evidence that it exists — and one of those researchers said again recently that he had found further proof of the mysterious planet.

If those researchers are correct, then Planet 9 would be 10 times as big as Earth and would be 1,000 times further from the Sun than we are.

The mystery of the extinction events that happen every 27 million or so years is an equally long-investigated and mysterious problem. Nobody is really clear why the comets tend to arrive on such an apparently regular schedule —but potential other explanations include a companion star to our own sun or extra risk as we travel through the spiral arms of the Milky Way.

But the new theory suggests that if the idea of the periodic extinctions is true, then it may be that the particular orbit of Planet 9 is to blame. It proposes that as the planet moves around the solar system, it passes through the Kuiper Belt — an area of the outer solar system full of icy objects — every 27 million years, knocking comets towards us and into the inner solar system.

Once they arrive there, they can smash into the Earth and reduce the sunlight getting to us, potentially leading to the extinction events, the researchers claim.