Pluto is one of the dwarf planets on the Kuiper belt, a ring of solar bodies beyond the planet Neptune. It was discovered in 1930 by Clyde Tombaugh. Pluto was initially the 9th planet of our solar system, but in 2006, following the definition of the term planet by the IAU, it was reclassified as a dwarf planet. Pluto is made up of rocks and ice and its mass is about 1/6 the mass of the Moon. Its orbit is moderately eccentric and inclined, ranging from 30 to 49 AU from the Sun. Thus, it sometimes gets closer to the Sun than the Planet Neptune.
Discovery of Pluto
The search for the ninth planet was initiated in 1906 by Percival Lowell who founded the Lowell Observatory in Arizona. He named the planet “Planet X.” By 1909, Lowell had suggested several coordinates for the planet. However, his research was cut short by his death in 1916. Unknown to him, he had captured some unclear images of Pluto during his survey in March and April of 1915. The search for Planet X was suspended after Lowell’s death following a legal battle between Lowell’s wife and the Lowell Observatory over the legacy of Lowell. The search resumed in 1929 with Clyde Tombaugh tasked with the job of locating the planet. After a year of intense search, Clyde discovered a moving object from some of the images captured on January 23 and 29, 1930. On March 13, 1930, the news on the discovery of the new planet was conveyed to the Harvard College of Observatory.
Naming of the 9th Planet
The news on the new planet discovered made headlines worldwide. Lowell Observatory embarked on a task to name the planet. Several names were suggested from all over the world. Although the object was named Planet X, a proper name was needed that matched the other planets in the Solar System. Some of the names that were suggested included Zeus and Percival but they were all disregarded.
An 11-year old girl from England named Venetia Burney suggested the name “Pluto.” She had interest in classical mythology and she thought Pluto would make a good name. Venetia suggested the name in a conversation with her grandfather who was a former librarian at the University of Oxford. Her grandfather passed the name to an astronomy professor at the university, Herbert H Turner, who passed it to the colleges in the US.
At the Lowell Observatory, members were allowed to vote on the three names that had been short-listed. The three names included Minerva, Cronus, and Pluto. All the members voted for Pluto, rejecting the other two. Minerva was rejected because it was already a name for an asteroid while Cronus was rejected because it had been suggested by an unpopular astronomer Thomas Jackson See. The name “Pluto” was published on May 1, 1930. Venetia was awarded five pounds for providing the name.
The name Pluto has been used by several languages to refer to mythological god of the underworld. In fact, when Venetia suggested the name, she thought that Hades, the Greek god of the underworld, made a good name. However, the name Pluto matched the names of the Roman gods given to other planets in the solar system.