Today in History—February 18: From Kansas to the Kuiper Belt

The butterfly effect, Midwest edition: A hailstorm in Kansas helped lead to the discovery of the dwarf planet Pluto.

In 1928 a hailstorm hit the Tombaugh family farm in Burdett, Kansas, and wiped out the crops—and the money earmarked for Clyde Tombaugh, 22, eldest of six, to go to college.

Clyde was undeterred: He didn’t want to be a farmer. He had fallen in love with astronomy as a teenager, and when his family moved from Illinois to Kansas in 1922, he discovered the dark skies there made ideal viewing for the 2.25-inch telescope his dad had bought from Sears.

When that telescope wasn’t enough, Clyde used instructions in Popular Astronomy to build his own. His first attempt wasn’t great. So he dug a 24-foot underground testing room on the farm and taught himself to grind and test optics and build better telescopes. With a 9-inch Newtonian reflector he completed in 1928, he made detailed drawings of Mars and Jupiter.

He read a report on Mars written by Lowell Observatory staff, so he sent them his drawings. The director was so impressed that he offered Clyde a job in Flagstaff, Arizona, as an assistant and groundskeeper in January 1929.

At the time Lowell was resuming the search for what its founder called Planet X, a hypothetical planet thought to exist past Neptune.

By day Clyde shoveled snow and hauled coal. By night he operated the observatory’s astrograph, a refracting photographic telescope, keeping it fixed on one point—a guide star—for the entire hour-long exposure. The images were rendered onto 14-by-17-inch plates. He could take only a few each night.

Then he compared photos of the same star fields taken days apart using a blink comparator, which flipped rapidly between two images to simulate movement. Stars stayed still; things that moved stood out. Each plate contained 50,000 to 900,000 specks to check.

Reviewing plates from January 23 and January 29 in 1930, Clyde spotted it: a tiny pinprick of light that had shifted enough to suggest it wasn’t a star.

And that’s how a 24-year-old Kansas farm boy who taught himself astronomy discovered Pluto on this day in 1930. The observatory confirmed the findings with more images and announced the discovery in March.

That hailstorm had set Clyde on a course for the outer solar system. And once the discovery was publicized, he got his college dream, too: He received a scholarship to the University of Kansas and completed his M.A. in astronomy while working at Lowell.