The 170-Year Search for a Planet Beyond Neptune
There may be a ninth planet at the edge of our solar system — it’s not Pluto and it’s not “Planet X.”
By Ana Aceves and Caitlin Saks
Planet Nine’s existence is not the first time astronomers have predicted a planet they couldn’t see. Clyde Tombaugh was looking for Planet X when he accidentally found Pluto. After Voyager 2 flew by Neptune in 1989, new calculations determined there was no Planet X. But three years ago, a disturbance was detected at the far reaches of the Solar System.
