According to research published by a faculty member of the University of Arkansas Department of Mathematical Sciences, Daniel Whitmire, periodic mass extinctions on Earth, as indicated in the global fossil record, could be linked to a suspected ninth planet. Whitmire's new research, published in the January issue of Monthly Notices of the Royal Astronomical Society, says that as yet undiscovered "Planet X" triggers comet showers linked to mass extinctions on Earth at intervals of approximately 27 million years. Though scientists have been looking for Planet X for 100 years, the possibility that it's real got a big boost recently when researchers from Caltech inferred its existence based on orbital anomalies seen in objects in the Kuiper Belt, a disc-shaped region of comets and other larger bodies beyond Neptune. If the Caltech researchers are correct, Planet X is about 10 times the mass of Earth and could currently be up to 1 000 times more distant from the Sun. Whitmire and his