Could 'Planet X' Cause Comet Catastrophes on Earth?
This is an artist's impression of a Kuiper belt object in orbit around the sun — could a massive planet also be out there?
Credit: NASA

As astronomers track down more clues as to the existence of a large world orbiting the sun in the outer fringes of the solar system, a classic planetary purveyor of doom has been resurrected as a possible trigger behind mass extinctions on Earth.

Yes, I'm talking about "Planet X." And yes, there's going to be hype.

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