Year: Day to Day Men: March 13
Perched
The thirteenth of March in 1930 marks the discovery of Pluto, the ninth largest and tenth most massive known object to directly orbit the sun of this system. Like other objects in the Kulper belt, the circumstellar disc in the outer solar system, Pluto primarily consists of rock and frozen volatiles such as methane, ammonia and water.
In the 1840s, French astronomer and mathematician Urbain Le Verrier used Newtonian mechanics to predict the position of the, as yet, undiscovered planet Neptune after analyzing deviations in the orbit of Uranus. Subsequent observations of Neptune in the late 1800s led astronomers to speculate that Uranus’s orbit was being affected by another planet beside Neptune.
In 1906, wealthy astronomer and mathematician Percival Lowell began an extensive project at the Lowell Observatory to search for a possible ninth planet, that he termed Planet X. Lowell and astronomer William H. Pickering had by 1909 suggested several possible celestial coordinates for this Planet X. Lowell continued his search, with calculations established by mathematical genius Elizabeth Langdon Williams, without any success until his death in 1916.
Unknown to Lowell, his research surveys had captured two faint images of Pluto on March 19th and April 7th of 1915; however, these images were not recognized as being of Pluto. There exists fourteen other known observations of Pluto which predate its discovery, the earliest being that of the University of Chicago’s Yerkes Observatory on the 20th of August in 1909.
In 1919, Percival Lowell’s widow, Constance Lowell, entered into a ten-year legal battle with the Lowell Observatory over her husband’s legacy. The search for the unknown planet did not resume until 1929. American astronomer Clyde Tombaugh, at the age of twenty-three, continued Lowell’s quest. His task was to systematically image the night sky in pairs of photographs. Each pair would be examined to determine if any objects had shifted position. This was done through the use of a blink comparator that shifts back and forth between photographs to create the illusion of movement for any object that had changed position in the photographs.
On the 18th of February in 1930, after a year of searching, Tombaugh detected a possible moving object on the photographic plates taken on January 23rd and 29th. A photograph of lesser quality taken on the 21st helped confirm the movement. After the Lowell Observatory had taken additional photographs to confirm the discovery, a telegram with the news was sent to the Harvard College Observatory on the 13th of March in 1930.
The name Pluto came from the Roman god of the underworld; it is also an epithet for Hades, the Greek equivalent of Pluto. As one Plutonian year corresponds to 247.94 Earth years, Pluto will be back in the same position of its discovery in 2178. On the twenty-ninth of July in 2005, astronomers at Caltech announced the discovery of a new trans-Neptunian object, named Eris, which is substantially more massive than Pluto and the most massive object discovered in the solar system since Neptune’s moon, Triton, in 1846.