When Clyde Tombaugh built his first telescope at the age of 20, he didn't even know that it was setting him forward on a path that would eventually lead him to the discovery of the first known dwarf planet, Pluto.
As a young researcher, Clyde worked for the Lowell Observatory in Flagstaff, Arizona. His journey in Lowell observatory started in an interesting and unexpected manner. Unhappy with the store-bought telescopes, Tombaugh used to construct his own telescopes.In 1928, he put together a 23-centimeter reflector out of the crankshaft of a 1910 Buick along with parts of a cream separator. Using this telescope, young Clyde made detailed observations of Jupiter and Mars, which he sent to Lowell Observatory in hopes of garnering some sort of feedback from professional astronomers. However, instead of receiving constructive criticism, Tombaugh was given the job to perform a systematic search for a trans-Neptunian planet (also called Planet X), which was predicted by Percival Lowell and William Pickering. This is how the journey towards discovery of Pluto by Clyde Tombaugh began.
Subsequent observations of Neptune in the late 19th century led astronomers to speculate that Uranus's orbit was being disturbed by another planet besides Neptune. This unknown planet was known as Planet X. Lowell and his observatory conducted this search until his death in 1916, but to no avail, until Clyde took over the responsibility.
The telescope Which clyde was supposed to operate was equipped with a camera that used to take two photographs of the sky on different days. A device known as a blink compactor rapidly flipped back and forth between the two photographs. Stars and galaxies essentially remained unmoving in the images, but anything closer could be visually identified by its motion across the sky. Tombaugh spent approximately a week studying each pair of photographs, which contained over 150,000 stars, and sometimes nearly a million.
Finally, On Feb. 18, 1930, Tombaugh noticed movement of a starry speck that moved in relative position from one plate to the other by the amount he had hoped for. It was planet X. After studying the object to confirm it, the staff of Lowell Observatory officially announced the discovery of a ninth planet on March 13, which was later named Pluto.
At the time of discovery, Pluto was considered a planet but was later controversially, it was reclassified as a dwarf planet in 2006, though this came out to be heartbreaking for many !