The Discovery of Pluto

 

Lowell Observatory is the place where the planet Pluto was discovered in 1930.  Percival Lowell, built the observatory, first to study the planet Mars, then he began a search for "Planet X" in 1905.  In 1929 Clyde Tombaugh, a farm boy and an amateur astronomer and telescope maker from Kansas was hired by Lowell Observatory to continue the search. He used this 13" astrograph, which is a telescope used for taking photographs.  He used 14" x17" glass plates and made hour-long exposures of different parts of the sky.  Then several days later he would photograph the same areas, and compare the plates.  If an object moved on the plates between the two exposures, when he viewed the plates, the object would appear to jump.  Within a year, he had found the object which was then named "Pluto."  He died at age 90 in 1997, and a small portion of his ashes was placed aboard the New Horizons spacecraft, which went to Pluto, now no longer considered a planet.

This is the back of the astrograph, showing the aluminum plate holder on the back of the telescope.