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Discovery And Naming Of Pluto

On February 18, 1930 Pluto was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona when he compared photographic plates taken on January 23 and 29. After the observatory obtained confirming photographs, the news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930. The planet was later established on photographs dating back to March 19, 1915. Tombaugh was searching for a "Planet X" to enlighten discrepancies in the predicted orbit of Neptune. It is currently known these discrepancies were an relic of the slightly incorrect value then assumed for the mass of Neptune.

In the affair of Pluto the discretion of naming the new object belonged to Lowell Observatory and its director, Vesto Melvin Slipher, who, in the words of Tombaugh, was "urged to suggest a name for the new planet ahead of someone else did". Shortly suggestions began to pour in from all over the world. Constance Lowell, Percival's widow who had deferred the search through her lawsuit, proposed Zeus, then Lowell, and at last her own first name, none of which met with any eagerness. One young couple even wrote to ask that the planet be named after their newborn child. Mythological names were much to the fore: Cronus and Minerva (proposed by the New York Times, unaware that it had been proposed for Uranus some 150 years earlier) were high on the list. Also there were Artemis, Athene, Atlas, Cosmos, Hera, Hercules, Icarus, Idana, Odin, Pax, Persephone, Perseus, Prometheus, Tantalus, Vulcan, Zymal, and many more. One barrier was that many of the mythological names had already been chosen to the numerous asteroids. Almost all the female names had been used up, and male names were generally kept for objects with unusual orbits.

The name retained for the planet is that of the Roman god Pluto, and it is also intended to suggest the initials of the astronomer Percival Lowell, who predicted that a planet would be found beyond Neptune. The name was first recommended by Venetia Burney, at the time an eleven-year-old girl from Oxford, England. Over the breakfast table, one morning her grandfather, who worked at Oxford University's Bodleian Library, was reading about the discovery of the new planet in the Times newspaper. He asked his granddaughter what she thought would be good name for it. Venetia thought that as it was so cold and so distant it should be named after the Roman God of the underworld. Professor Herbert Hall Turner cabled his colleagues in America with this idea, and after favorable concern which was almost undisputed, the name Pluto was formally adopted and a declaration made by Slipher on May 1, 1930.