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Lowell Observatory Archives

Pluto

Pluto

On March 13, 1930 Lowell Observatory made history when it announced the discovery of a ninth planet in the solar system. Astronomers had long theorized about the existence of planets beyond Neptune, which at the time of its discovery was the farthest planet from the sun. In 1905, mathematician and astronomer Percival Lowell began his quest for the elusive "Planet X" with little more than determination and a small, loyal crew. Lowell did not live to witness the outcome of the search he had set in motion, but he paved the way for a future generations of explorers, including the 24 year-old amateur astronomer from Kansas who made the discovery.

The story of Pluto is one of dedication and persistence, and its legacy remains important to the field of astronomy today. This exhibit will first explore the initial search for Pluto and the many obstacles that the astronomers faced along the way. Next, you will take a deeper look into the discovery and hear about the experience from the discoverer Clyde Tombaugh through a recorded interview from 1989. You will also see scans of the original discovery plates, congratulatory letters sent to the observatory, newspaper articles, and other historic documents that highlight the public's response to finding a new planet. This exhibit also dives into the modern science surrounding Pluto, including NASA's 2015 New Horizons mission. In the pop culture section of this exhibit, you will discover how Pluto has been equally influential on popular culture, which is best captured by the name change of Mickey Mouse's beloved companion from "Rover" to "Pluto." Allow this exhibit to take you on a journey through time and space as you uncover the rich history behind the first planet discovered on American soil.