NASA rules out existence of 'Planet X'

Despite NASA's effort to track it down, there is no evidence for the existence of Planet X, astronomers have revealed.

The hypothetical world that may or may not be orbiting the sun beyond the orbit of Pluto has inspired many a doomsday theory. In the run-up to the much anticipated "Mayan Doomsday" of Dec. 21, 2012, the marauding Planet X was scheduled to make a inner-solar system dash, sparking gravitational mayhem, triggering civilization-ending solar flares.

The hunt for "Planet X" actually has roots in real science. In the mid- to late-19th Century, astronomers were tracking the gravitational perturbations of the gas giant planets in an effort to track down an undiscovered world in the outermost reaches of the solar system - this hypothetical massive planet was dubbed "Planet X."

However, this fascinating trail of discovery ended at the discovery of tiny Pluto in 1930. Lacking the gravitational oomph to explain the gravitational perturbations, it turned out that Pluto wasn't the Planet X astronomers thought it would be. After the realization that the gravitational perturbations observed were more likely observational error, Planet X became a story of legend.

The idea that the sun may have a stellar partner has also been investigated - perhaps there's a brown dwarf (a failed star) going unnoticed out there. Nicknamed "Nemesis," this binary partner could be evading detection.

A few oddities in the outer solar system have given astronomers pause to think that something massive might be lurking out there, however, whether it be a massive planet or sub-standard star.

Luhman and his team have analyzed data from NASA's Wide-Field Infrared Survey Explorer (WISE), a space telescope that carried out a detailed infrared survey of the entire sky from 2010 to 2011. If something big is lurking out there, WISE would easily have spotted it.

However, WISE has turned up no Planet X candidate. Previous observations by WISE have also ruled out the Planet X-comet perturbation theory, Discovery News reported.

According to a NASA news release, "no object the size of Saturn or larger exists out to a distance of 10,000 astronomical units (AU), and no object larger than Jupiter exists out to 26,000 AU. One astronomical unit equals 93 million miles. Earth is 1 AU, and Pluto about 40 AU, from the sun."

The study is published in The Astrophysical Journal.