A previously unknown giant planet may have been discovered lurking in the outer reaches of our solar system, US scientists announced on January 20. Nicknamed Planet Nine, the object "has a mass about 10 times that of Earth" and follows a "bizarre, highly elongated orbit in the distant solar system," said a statement by researchers at the California Institute of Technology (Caltech).
"In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the Sun." The report was published in the Astronomical Journal.
Researchers Konstantin Batygin and Mike Brown say have not yet observed the object directly.
Rather, they found it through mathematical modelling and computer simulations. The presumed planet has about 5,000 times the mass of Pluto, and scientists believe its gravity has affected the motion of dwarf planets in the outer solar system, essentially perturbing celestial bodies in the field of icy objects and debris beyond Neptune known as the Kuiper Belt. "Like a parent maintaining the arc of a child on a swing with periodic pushes, Planet Nine nudges the orbits of distant Kuiper Belt objects such that their configuration with relation to the planet is preserved," explained CalTech in a statement.
The planet could have been cast off during the early formation of the solar system, when four major cores grabbed up the gas around them and formed Jupiter, Saturn, Uranus and Neptune.
Perhaps Planet Nine represented a fifth core, that may have gotten too close to Jupiter or Saturn and been ejected into its current, distant orbit, said Brown.