It's dark and huge and almost certainly coming for us.
Prepare the planetray defence grid!
From the Herald, and pretty everywhere online today:
Astronomers at the California Institute of Technology have announced they have found new evidence of a giant icy planet lurking in the darkness of our solar system far beyond the orbit of Pluto. They are calling it "Planet Nine."
Their paper, published in the Astronomical Journal, describes the planet as about five to 10 times as massive as the Earth. But the authors, astronomers Michael Brown and Konstantin Batygin, have not observed the planet directly.
Instead, they have inferred its existence from the motion of recently discovered dwarf planets and other small objects in the outer solar system. Those smaller bodies have orbits that appear to be influenced by the gravity of a hidden planet — a "massive perturber." The astronomers suggest it might have been flung into deep space long ago by the gravitational force of Jupiter or Saturn.
An artist's impression of Planet Nine, which could sit at the edge of our solar system. Photo: R. Hurt / California Institute of Technology.
Telescopes on at least two continents are searching for the object, which on average is 20 times farther away than the eighth planet, Neptune. If "Planet Nine" exists, it's big. Its estimated mass would make it about two to four times the diameter of the Earth, distinguishing it as the fifth-largest planet after Jupiter, Saturn, Uranus and Neptune. But at such extreme distances, it would reflect so little sunlight that it could evade even the most powerful telescopes.