The discovery of a new celestial body in the outer solar system in 1930 presented astronomers with the task of giving it a permanent name. This world, initially hailed as the ninth planet, was incredibly distant, demanding a name that reflected its remote station. The story of how this object came to be called Pluto blends dedicated astronomical research and the imaginative suggestion of a young girl. The naming process, spanning from the object’s first sighting in February to the official announcement in May, captured the public’s imagination.
The Search for Planet X
The hunt for a ninth major planet was rooted in the mathematical predictions of astronomer Percival Lowell. He theorized that irregularities in the orbit of Uranus were caused by the gravitational influence of an unseen body. Lowell referred to this hypothetical world as “Planet X” and searched for it extensively at his observatory in Flagstaff, Arizona, until his death in 1916. The search for this elusive object resumed in 1929, led by a young assistant named Clyde Tombaugh.
Tombaugh meticulously photographed sections of the night sky using the observatory’s 13-inch astrograph, capturing hundreds of thousands of star images on glass plates. He then used a specialized viewing instrument, known as a blink comparator, to rapidly switch between images of the same sky region taken days apart. On February 18, 1930, after nearly a year of systematic searching, Tombaugh noticed a tiny, moving object on photographic plates taken in January. The confirmation of this faint, trans-Neptunian object fulfilled Percival Lowell’s prediction, setting the stage for its official naming.
The Originator of the Name
The news of the discovery traveled quickly, reaching the public in March 1930. In Oxford, England, 11-year-old Venetia Burney was having breakfast when her grandfather, Falconer Madan, read about the new planet in The Times. Madan, a retired librarian at the Bodleian Library, wondered aloud what the distant object should be named.
Venetia, who was interested in classical mythology, immediately suggested “Pluto.” The name referred to the Roman god of the underworld, who ruled over a dark and frigid domain far from the sun. This mythological association seemed perfectly suited for the remote, cold, and dim new world discovered at the edge of the solar system. Her grandfather was taken with the suggestion and mentioned it to his friend, Professor Herbert Hall Turner, an astronomer at the University of Oxford.
Professor Turner, recognizing the name’s appropriateness, transmitted Venetia’s idea by cable to his American colleagues at the Lowell Observatory. The suggestion for “Pluto” was one of approximately 150 names submitted to the observatory staff. The proposal’s origin, from a young enthusiast who understood the classical naming convention, made it stand out.
Formal Acceptance and Announcement
Upon receiving the cable, the staff at the Lowell Observatory, including V.M. Slipher and Clyde Tombaugh, began selecting the final name. They held an internal vote among the most favored nominations, which included names like Minerva and Cronus. The name “Pluto” quickly rose to the top and received a unanimous vote from the Lowell team.
A significant factor in the name’s favor was that the first two letters, ‘P’ and ‘L’, served as the initials of Percival Lowell, the astronomer who initiated the search for Planet X. This connection honored the observatory’s founder. After the internal decision, the name was proposed to the American Astronomical Society and the Royal Astronomical Society for formal approval.
The official announcement confirming the name Pluto was made on May 1, 1930, just over two months after the discovery. The fitting name, born from the imagination of a schoolgirl and endorsed by astronomers, was quickly adopted. Venetia Burney received a five-pound reward from her grandfather for her successful suggestion.