This is simply the 12th Planet being rediscovered...again! It's funny what a little disinformation will do to the gullible.

Planet X (1908): For decades, astronomers noted that Uranus and Neptune still did not follow their expected paths. Percival Lowell spent fruitless years looking for a "Planet X" to explain the anomaly. Astronomer Clyde Tombaugh, hired to carry on Lowell's effort, discovered Pluto in 1930— but only by luck, as Pluto is far too small to be Lowell's Planet X.

Washington Post
Mystery Heavenly Body Discovered, a front page story
31-Dec-1983
A heavenly body possibly as large as the giant planet Jupiter and possibly so close to Earth that it would be part of this solar system has been found in the direction of the constellation Orion by an orbiting telescope aboard the U.S. infrared astronomical satellite. So mysterious is the object that astronomers do not know if it is a planet, a giant comet, a nearby "protostar" that never got hot enough to become a star, a distant galaxy so young that it is still in the process of forming its first stars or a galaxy so shrouded in dust that none of the light cast by its stars ever gets through. "All I can tell you is that we don't know what it is," Dr. Gerry Neugebauer, IRAS chief scientist for California's Jet Propulsion Laboratory and director of the Palomar Observatory for the California Institute of Technology said in an interview.

Nemesis (1984): Daniel Whitmire and his colleagues, along with a group led by Richard Muller of the University of California at Berkeley, independently suggested our sun might have a low-mass companion star, which they called Nemesis, that sends swarms of comets earthward every 30 million years. The evidence for now looks suspect, but observations have still not conclusively ruled out the existence of Nemesis.