Clyde Tombaugh

Clyde Tombaugh loved the night sky.

He was a man who built his own tools. He even made his own lenses by hand.

He worked at a place called Lowell Observatory. There, he looked for a new planet. He used a tool to look at pictures.

He looked at two pictures of the sky. He saw a tiny dot move between them.

That moving dot was Pluto!

For a long time, people thought it was a planet. Clyde also found many other things in space. He found hundreds of rocks called asteroids. He even found many bright stars.

Clyde was a great star finder.

Clyde Tombaugh was an American astronomer. He is famous for finding Pluto in 1930.

Clyde grew up on farms in Kansas. He taught himself how to study the stars. He even built his own telescopes. He made lenses by hand using spare parts.

Later, he worked at the Lowell Observatory. He had a big job to do. He had to search for a hidden planet. To do this, he took many photos of the sky. He used a tool called a blink comparator.

This tool let him look at two photos. He would switch between the images very fast. Most stars stayed in the same place. But one tiny object seemed to jump. That moving object was Pluto!

For many years, people called Pluto the ninth planet. Later, scientists learned Pluto is part of the Kuiper belt. This is a group of icy objects far from the sun. Today, we call Pluto a dwarf planet. Clyde also found many asteroids and bright stars. He was a great explorer of the night sky.

Clyde William Tombaugh was a famous American astronomer and telescope maker. He is best known for discovering Pluto in 1930. This discovery was a huge moment in science. It was the first time anyone found something in the Kuiper belt. The Kuiper belt is a large group of icy objects far from the sun. For over seventy years, people called Pluto the ninth planet in our Solar System.

To find Pluto, Tombaugh used a very clever way of working. He used a machine called a blink comparator to look at photos. First, he took many photographs of the same part of the sky. He did this using a large telescope called an astrograph.

Then, he used the blink comparator to switch between two different images very quickly. Most stars stayed in the same spot in both pictures. However, one tiny object seemed to jump from place to place. This movement showed that the object was a moving planet rather than a distant star.

Tombaugh grew up on farms in Kansas and Illinois. He was largely self-educated in the ways of the stars. He even built his own telescopes using spare parts. He would grind lenses by hand to make them work. To test his telescope mirrors, he dug a deep pit in the ground. The pit was 24 feet long and 8 feet deep. This kept the air temperature steady so he could work better.

His big discovery happened on February 18, 1930. He found the object using images taken the month before. People had many ideas for what to name it. One name was Minerva, but that name was already used for an asteroid. Another name was Cronus, but people did not like it. Finally, an 11-year-old girl named Venetia Burney suggested Pluto. The name was officially chosen on May 1, 1930.

Tombaugh did much more than just find one planet. He identified hundreds of asteroids and many star clusters. He also found many galaxies and variable stars. He even helped study the Great Red Spot on Jupiter. Later in life, he taught at New Mexico State University. He worked hard to map the night sky for everyone to see. His work helped us understand the huge world beyond our own.

Clyde William Tombaugh was a highly skilled American astronomer and telescope maker. He is most famous for discovering Pluto in 1930. This discovery marked the first time humans detected an object in what we now call the Kuiper belt. The Kuiper belt is a vast region of icy bodies located far beyond Neptune. For over seven decades, Pluto was classified as the ninth planet in our Solar System.

Tombaugh's journey into science began with a deep, self-taught curiosity. Born in Illinois in 1906, he grew up on farms in Kansas. His interest in the stars was sparked by visits to the Yerkes Observatory and his uncle, an amateur astronomer. Because his family faced financial struggles due to bad weather and poor harvests, Tombaugh often had to work on the farm. He even dropped out of high school for a year to help prepare crops. Despite these challenges, he graduated in 1925 and began teaching himself optical engineering. He built his own telescopes using spare parts and ground lenses by hand. To test his telescope mirrors, he even dug a pit 24 feet long and 8 feet deep to ensure a constant air temperature.

In 1929, Tombaugh began working at the Lowell Observatory in Flagstaff, Arizona. He was assigned a specific mission: to search for a trans-Neptunian planet. This was also known as "Planet X," a body predicted by calculations from Percival Lowell's student, Elizabeth Williams, and William Pickering. To find it, Tombaugh used a specialized telescope called an astrograph.

He took photographs of the same section of the sky several nights apart. These images were captured on photographic plates.

To analyze these plates, Tombaugh used a device called a blink comparator. This machine allowed him to switch rapidly between two different images of the same sky area. As he shifted between the images, most stars appeared stationary because they are so distant. However, a moving object would appear to "jump" from one position to another. This visual jump indicated that the object was moving through our solar system. On February 18, 1930, Tombaugh noticed such a movement. This object had an orbit beyond Neptune, which meant it was not just an asteroid. He had found the elusive ninth planet.

Naming the new world was a significant event. Three mythological names were initially considered: Minerva, Cronus, and Pluto. Minerva was rejected because it was already the name of an asteroid. Cronus was dismissed because of a dislike for its primary supporter, Thomas Jefferson Jackson See. An 11-year-old English girl named Venetia Burney suggested Pluto. The name was fitting because Pluto can render himself invisible in mythology. The name was officially adopted on May 1, 1930, after receiving unanimous approval from major astronomical societies.

Tombaugh's career extended far beyond this single discovery. He identified hundreds of asteroids, including 15 that are officially credited to him. He also discovered various star clusters, galaxies, and variable stars. In 1936, he may have discovered the Perseus–Pegasus Filament, a massive galaxy structure spanning roughly a billion light-years. Later, as a professor at New Mexico State University, he led the Planetary Patrol project. This work helped determine the rotation period of Mercury and monitored Jupiter's Great Red Spot.

Our understanding of Pluto changed significantly in the late 1990s and early 2000s. Astronomers discovered many other icy bodies in the Kuiper belt. When a body named Eris was found to be more massive than Pluto, the International Astronomical Union reclassified Pluto. On August 24, 2006, Pluto became a dwarf planet. This left only eight major planets in our Solar System. While Tombaugh had resisted this change during his life, his widow noted that as a scientist, he would have understood the need to adapt to new data.