mar 13, 1930 - Planet X is discovered by Clyde Tombaugh
Description:
(Initially named "Planet X" by speculative astronomers who believed there was another planet behind Neptune, Venetia Burney had submitted Pluto to her grandfather, Falconer Madan, who would then suggest it to Herbert Turner)(I'm surprised they even discovered Pluto. Urbain Le Verrier speculated that there was a celestial object meddling with Uranus' orbit in the 1840s, and Percival Lowell's motives to discover Planet X were tied to Le Verrier's speculations. Lowell definitely would've discovered the Iris, but that's speculative.)
Added to timeline:
Date:
mar 13, 1930
Now
~ 95 years ago