Exciting news! The solar system appears to have a new ninth planet. Today, two scientists announced evidence that a body nearly the size of Neptune—but as yet unseen—orbits the sun every 15,000 years. During the solar system’s infancy 4.5 billion years ago, they say, the giant planet was knocked out of the planet-forming region near the sun. Slowed down by gas, the planet settled into a distant elliptical orbit, where it still lurks today.
The new research, published in The Astronomical Journal by Brown and his colleague Konstantin Batygin, is sure to cause a stir. He is proposing the existence of a real ninth planet of the Solar System, dubbed “Planet Nine” and ostentatiously nicknamed “Phattie,” that would be almost the size of Neptune.
“For the first time in over 150 years, there is solid evidence that the Solar System’s planetary census is incomplete,” said Batygin in a statement.
One possible explanation for the planet’s existence, according to the authors, is that it was a giant planet core that was ejected during the early Solar System, something that may be common in planetary systems.
The discovery of a ninth planet in the Solar System would be huge, and that’s an understatement. Astronomers have previously predicted the existence of hundreds of dwarf planets beyond the orbit of Pluto in the Kuiper Belt, but so far no solid theories exist for a large planet like Planet Nine.