Is Planet Nine Even Real?
A year and a half after it was proposed, astronomers are still debating whether the giant mystery planet actually exists.
When Mike Brown first proposed that a hidden, massive planet lurks in the outer reaches of our solar system, he was confident someone would prove him wrong. “Planet Nine,” as the hypothetical world was nicknamed, was his explanation for the strange movements of half a dozen distant, icy planetoids that are farther away and smaller than Pluto: In theory, this huge, somehow-undiscovered planet could sway their orbits. But surely astronomers would be quick to find a more obvious explanation.
“Shockingly, in a year and a half, nobody has,” says Brown, an astronomer at the California Institute of Technology. “There have been so many claims of planets in the last 170 years, and they wrong. But I’m clearly a true believer at this point.”
