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Killer ‘Planet X’ myth debunked

AFP-JIJI

An elusive planet appeared to explain Uranus’ wobbly orbit for 200 years. And a sister sun was theorized to be near our solar system, causing asteroids to swerve toward Earth. But researchers have found no evidence for “Planet X” or “Nemesis.”

“The outer solar system probably does not contain a large gas giant planet, or a small, companion star,” concluded University of Pennsylvania astronomer Kevin Luhman, who directed the study using NASA’s Wide-field Infrared Survey Explorer (WISE) telescope. The results were published in The Astrophysical Journal.

Most theories had estimated Planet X to be up to four times the size of Jupiter. But the images gathered by the telescope found that nothing larger than Saturn exists up to a distance 10,000 times farther from the sun than the Earth’s orbit.

Scientists first imagined the existence of Planet X in 1781 after they discovered Uranus, a gas giant whose orbital variations were apparently incompatible with Newton’s laws of gravity. Observers concluded that these irregularities could be explained by the gravitational influence of an unknown planet. Finally, in the 1990s, researchers determined that they had slightly overestimated the mass of Neptune, accounting for Uranus’ orbital behavior.

The existence of Nemesis, a sunlike star nearby, was first posited in the 1980s. The star, by occasionally coming closer to the sun, interfered with the orbit of comets and asteroids, sending them inward toward the sun and leading them to occasionally hit the Earth. But the WISE telescope didn’t find anything.

The study did uncover 3,525 stars and brown dwarfs — celestial objects too small to sustain normal nuclear fusion — within 500 light-years of the sun.