Social Studies: Planet X

In 1894, with the help of William Pickering, Percival Lowell, a wealthy Bostonian aristocrat, founded the Lowell Observatory in Flagstaff, Arizona. In 1906, convinced he could resolve the conundrum of Uranus's orbit, he began an extensive project to search for a trans-Neptunian planet, which he named Planet X. The X in the name represents an unknown and is pronounced as the letter.

Lowell's sudden death in 1916 temporarily halted the search for Planet X. Failing to find the planet, according to one friend, "virtually killed him". In 1929 the observatory's director, Vesto Melvin Slipher, summarily handed the job of locating the planet to Clyde Tombaugh, a 22-year-old Kansas farm boy who had only just arrived at the Lowell Observatory after Slipher had been impressed by a sample of his astronomical drawings.

By the beginning of 1930, Tombaugh's search had reached the constellation of Gemini. On 18 February 1930, after searching for nearly a year and examining nearly 2 million stars, Tombaugh discovered a moving object on photographic plates taken on 23 January and 29 January of that year. A lesser-quality photograph taken on January 21 confirmed the movement.

The decision to name the object Pluto was intended in part to honour Percival Lowell, as his initials made up the word's first two letters.

Sources: Wikipedia
Greatest Stories Never Told by Rick Beyer