Clyde Tombaugh: Biography, Facts & Discovery

Instructor: Betsy Chesnutt

Betsy teaches college physics, biology, and engineering and has a Ph.D. in Biomedical Engineering

Clyde Tombaugh was an American astronomer who is remembered as the discoverer of the dwarf planet Pluto. In this lesson, learn about Tombaugh's amazing life and scientific discoveries!

Who Was Clyde Tombaugh?

What does it take to make a major scientific discovery? Do you need to go to college first or maybe even get a Ph.D.? Many people would say yes to these questions, but back in 1930, a young farmer and amateur astronomer named Clyde Tombaugh proved them wrong when, without any college education or formal training in astronomy, he discovered a new object orbiting our Sun-- the dwarf planet Pluto.

Tombaugh's Early Life

Clyde Tombaugh was born on a small farm in Illinois in 1906. He grew up looking at the stars with his father, who was also very interested in astronomy. Tombaugh planned to attend college and become a professional astronomer, but the year before he planned to enroll, a storm destroyed his family's crops and there was no money left for him to go to college.

Many people might have given up on the dream of becoming an astronomer then, but not Tombaugh. He kept going, even if he had to do it from the farm! He wanted a better telescope than what he could find in stores, so he starting building his own when he was only 20 years old. He grounded the mirrors himself and used parts from an old car and a cream separator he found on the farm to build a large but very accurate telescope.

A young Clyde Tombaugh built his own telescope on his family farm and used it to make very detailed images of Jupiter and Mars. These images were able to land him a job at the Lowell Observatory, where he would quickly cement his place in history with the discovery of Pluto.
clyde tombaugh with his telescope

By 1928, he had a working telescope and he used it to make very detailed images of Jupiter and Mars. He sent his astronomical images to the Lowell Observatory in Arizona, and scientists there were so impressed with his work that they offered him a job!

Discovery of Pluto

Tombaugh moved to Arizona and started working at the Lowell Observatory in 1928. Percival Lowell founded the observatory in 1894 and had predicted that there was a planet past Neptune that no one had yet discovered. He called it Planet X. When Tombaugh arrived at Lowell, he was given the task of trying to locate this mysterious Planet X. It didn't take him long to do it.

To search for Planet X, Tombaugh used a telescope to take pictures of the same region of the sky for many nights in a row. Then, he used a device called a blink comparator to compare the images. This device let him quickly switch between images so he could identify any objects that appeared to be moving. Stars should not appear to move because they are very far away from Earth, while planets, which are much closer, would appear to move across the sky. In 1930, Tombaugh found what he was looking for. In a part of the sky that Lowell had predicted Planet X might be found, he saw a moving object.

Over the next few weeks, he confirmed that this object did have an orbit that was beyond that of Neptune and that it was not an asteroid. The mysterious Planet X had finally been found, thanks to a clever farmer who wasn't able to afford to go to college. Planet X was renamed Pluto, based on a suggestion made by an 11-year-old English girl named Venetia Burney. Pluto is the Roman god of the underworld, and he was said to have the ability to make himself invisible, so it seemed a good name for a planet that had defied all attempts to locate it for many years.

Tombaugh's Other Contributions to Science

After discovering Pluto, Tombaugh was finally able to go to college, earning a Bachelor's degree in astronomy from the University of Kansas in 1936, and a Master's degree two years later. He continued to work at the Lowell Observatory until 1945, where he discovered many new asteroids, stars, galaxy clusters and even a supergalaxy cluster.

During World War II, he worked at Northern Arizona University, teaching navigation skills to naval officers and personnel. He later worked at the White Sands Missile Range, and then spent the last 18 years of his career teaching astronomy at New Mexico State University from 1955-1973.

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