Clyde Tombaugh and the Mysterious Satellite

During the mid-19th century reports of strange motions in the orbits of Uranus and Neptune led astronomers, among them Percival Lowell, to think that perhaps another celestial body was having a gravitational effect on their paths through space. Lowell searched for a mysterious ninth planet until his death in 1916. It was to be fourteen years later before Clyde Tombaugh, a research assistant at the observatory founded by Lowell, would discover this new world. However, Tombaugh is not only known as the discoverer of Pluto; he is also credited with the discovery of some other objects possibly even of an extra-terrestrial origin. Can this esteemed astronomer really have discovered a mysterious satellite?



Clyde Tombaugh (1906-1997) was from a farming family in Illinois and had an interest in astronomy from a young age, inspired by seeing Saturn’s rings and Jupiter’s moons using his uncle’s telescope.  Tombaugh was unable to afford college but he taught himself geometry and trigonometry and built his own telescope at 20 years old by following an article in a Popular Astronomy magazine. After trial and error he was able to build other telescopes which allowed a better view of objects in the night sky. He sought advice by sending drawings and observations of the planets, Mars and Jupiter, to the Lowell Observatory in Flagstaff, Arizona; instead of feedback, he was offered a job by its director Vesto Slipher.


Image Clyde Tombaugh with his homemade telescope. This piece of kit helped him land a job at the Lowell Observatory. (Image credit:

Clyde Tombaugh with his homemade telescope. This piece of kit helped him land a job at the Lowell Observatory. (Image credit:


Tombaugh’s new job was to use the observatory’s new 13” astrograph telescope to image the sky around the ecliptic every few days and then compare the images for any movement. After ten months, in February 1930, Tombaugh discovered Pluto. The Solar System now had nine planets (or so everyone thought). Tombaugh then won a scholarship to the University of Kansas completing his undergraduate studies in astronomy in 1936 and his masters in 1939. During his time at the Lowell Observatory, Tombaugh also discovered hundreds of stars and asteroids as well as two comets, and some star and galaxy clusters. He was drafted for wartime military service, teaching navigation for the US Navy. When WWII was over, the Lowell Observatory did not have the funds to rehire Tombaugh so he took a new job at a US Army ballistics research lab at White Sands Missile Range in 1946. This was based in Las Cruces, New Mexico and his role was to create an optical device which could detect and track missiles.

Percival Lowell searching for the elusive 9th planet?  at Tombaugh’s future workplace, the Lowell observatory in Arizona. Credit: Wikimedia.

Percival Lowell searching for the elusive 9th planet at Tombaugh’s future workplace, the Lowell observatory in Arizona. (Image credit:


During his time at Lowell observatory, and with his discovery of many asteroids, Tombaugh was led to consider the possibility of near Earth asteroids and the problems connected to tracking these fast moving objects. In 1943, Tombaugh unsuccessfully tried to track asteroid 2101 Adonis, this was one of the first near-earth asteroids discovered back in 1936.  Tombaugh also proposed that perhaps some of these small asteroids could be captured by our planet’s gravitational attraction and become natural satellites of the Earth.  A Near Earth Satellite search proposed by Tombaugh in 1952 funded by the Army Office of Ordnance Research was initiated the following year to consider the risks of such satellites to space exploration with the research being conducted Tombaugh’s previous workplace, the Lowell Observatory in Arizona.

Tombaugh’s research was proposed to try to photograph objects with a magnitude of down to +13 (Pluto at maximum brightness has an apparent magnitude of 13.65). Any moving astronomical bodies would be identified as a dot or short trail on the photographic plates. Moonless nights from December 1953-October 1958 were the prime opportunity to use the Observatory’s Schmidt camera, an 8.5 inch telescope with a wide field of view to search for any potential satellites of the Earth.

Lincoln La Paz (1897-1985) an astronomer at the University of New Mexico (who has become widely-known among UFOlogists for his suggestion that  green fireballs sighted over the US south west might be alien probes rather than meteors) published a journal article in 1954 on the idea of other satellites of the Earth. In this article he references Clyde Tombaugh and his army research in a footnote. After the published admission that the US government were looking for satellites around the Earth, the media went into overdrive. Articles such as “Armed Forces seek stepping stone to stars” were published and with famous astronomers involved, this was big news. What were they looking for? Was it going to be a space base? Just what was Tombaugh not telling people?

Donald Keyhoe (1897-1988) was an American naval aviator and later an author at the time. He produced many articles on UFO’s and he claimed he was able to use his military connections to find out more. In the early 1950s Keyhole published books on flying saucers, and his 1954 book Flying Saucers from Outer Space included interviews from military personnel on their experiences. Newspaper articles published in May 1954 have seemingly merged together the details of Keyhoe’s book and well as the Tombaugh research and produced articles claiming that the military are looking for artificial satellites. Not that the media ever get things wrong but this seems very much a case of 2+2=10! These incorrect articles are still regurgitated as proof of the Black Knight Satellite conspiracy.

Several faint objects were actually detected by Tombaugh and his team but all were either passing asteroids, or even defects on the photographic plates. In 1959, Tombaugh announced the area around Earth was free of any satellites. However by this stage, the media had already created a whirlwind conspiracy about the study and its results in numerous newspaper articles. Tombaugh and La Paz were both connected to this alien satellite conspiracy to which they denied which only seems to make conspiracy hunters all the more sure of their involvement. A Popular Mechanics article in October 1955 also accuses Tombaugh of being “closemouthed” on his results. However the study was still on-going at this point and Tombaugh was waiting on a lunar eclipse in November 1956 to allow the opportunity to photograph the sky in optimal conditions.

In the 1950’s the Army Office of Ordnance Research did fund Clyde Tombaugh to complete a search of the night sky in order to detect the dangers for space exploration. In a time of growing suspicions between East and West after the post WWII talks broke down, the Americans were keen on ensuring their rockets (or perhaps missiles) were not going to collide with any natural satellites. With the Soviets successfully launching Sputnik in 1957 (in the middle of Tombaugh’s research), the Space Race was instigated and the Americans were trailing behind.

New horizons Space craft carrying a little part off Tombaugh. Credit: NASA

New Horizons Space craft carrying a little part of Tombaugh. Credit: NASA


As far as Tombaugh finding or even hunting for extra-terrestrial satellites is concerned, this is very much a case of poor journalism implicating Tombaugh by a footnote in La Paz’s article. After his work with the military Tombaugh returned to research the geology of Mars and then taught astronomy the rest of his time at the New Mexico State University. Even after his retirement in 1973, Tombaugh continued to write and he toured giving talks to raise money for the Clyde Tombaugh scholarship fund to help encourage post-doctoral research. Tombaugh died at his home in January 1997. In 2006, a spacecraft headed for Pluto called New Horizons was launched carrying on board some of his ashes as a memorial for the research he conducted and his discovery of Pluto. In 2015, New Horizons will arrive at Pluto and hopefully help us continue to learn about Tombaugh’s discovered planet.

(Article by Martina Redpath, Education Support Officer)