Pluto: No Longer a Planet But Still a Star
“How I Killed Pluto and Why It Had It Coming,” a new book by astronomer Mike Brown was reviewed by James Kennedy in The Wall Street Journal (11-26-2010) last week. Kennedy mentions Brown’s integrity, his “fresh voice,” and his good will toward fellow astronomers and notes that this makes the “death” of Pluto as a planet easier to bear.
That’s all well and good, and yet I hold no particular fondness for Pluto, the planet. My regret over Pluto’s change of status is the potential loss of a wonderfully American story about the “farm boy from Kansas” who discovered it.
How a Farm Boy Came to Discover a Planet
Clyde Tombaugh (1906-1997) was an unlikely person to be the first American credited with discovering a planet. Tombaugh grew up on a farm near Burdett, Kansas, and during his free time, he experimented with parts of old cars and farm machinery, eventually building his own telescope. By 1927, he was satisfied with the way the telescope operated, and he began scanning the dark night skies in western Kansas and sketching what he saw. He sent these drawings to scientists at the Lowell Observatory in Flagstaff, Arizona, hoping to get some feedback on his work. The scientists must have seen something remarkable in the young fellow’s drawings as they hired him to come to work at Lowell, even though he had only a high school diploma.
Lowell Observatory was founded in 1894 by Percival Lowell, the scion of a well-established Massachusetts family. Lowell devoted his life to a search for water on Mars as well as other investigations, including a hunt for another planet, referred to as Planet X. Though Lowell died in 1916, the staff at the observatory was still in pursuit of his dream.
Tombaugh’s original assignment at the observatory was to use a new 13-inch f/5 camera to photograph the skies in search of this possible planet. Soon he was also given the job of scanning photographic plates using a Zeiss blink comparator, a pre-computer device that permitted astronomers to find differences between photographic plates taken of the same area of the sky at different times. (Scanning photographic plates was a very necessary and important job, but it was tedious and was often performed by clerical workers. In those days, it was the type of job women were sometimes hired to do.)
On February 25, 1930, Tombaugh was looking at the plates photographed on January 23 and January 29 when he noticed a speck of light shifting positions on successive plates exactly as a trans-Neptunian planet should. He thought he had found a new planet. The scientists verified what Tombaugh pointed out to them, and on March 13, 1930, they announced the discovery of a ninth planet.
The excitement of this discovery–the first planet to be identified since 1846 when Neptune was identified–was great. Percival Lowell’s dream was realized, right at the observatory he founded, and Americans were enchanted by the thought that the planet had been discovered by a U.S. citizen. Tombaugh was honored by organizations throughout the world.
Naming the Planet
Planets have always been named after Greek or Roman gods. Some of the closer planets were known to the ancient Greeks and Romans, for they noted that in the night sky some “lights” moved while others didn’t, and they called the ones that did planets from a Greek term meaning “wanderer.” The custom of naming them after the gods originated at this time.
Today the official naming organization for planets is the International Astronomers Union, but before they had an opportunity to meet after the discovery of Planet X, the newspapers were filled with suggestions from all types of people and organizations. Among the names floated out were Atlas, Zymal, Artemis, Perseus, Vulcan, Tantalus, Idana, and Minerva.
The name Pluto was actually suggested by an eleven-year-old girl who lived in Oxford, England. This wasn’t just any little girl, however. Venetia Burney’s grandfather, Falconer Madan, was librarian of the Bodleian Library of Oxford University, and he happened to read the story of the new planet’s discovery at breakfast on March 14, 1930, and mentioned it to his granddaughter. Venetia suggested to her grandfather that Pluto, the name of the god of the underworld, would be fitting for the newest planet that was so very far away. Her grandfather contacted one of his associates, who sent a telegram on to the Lowell Observatory.
The combination of the fitting mythological god and the fact that the first two letters of the name could serve to honor the initials of the original astronomer, Percival Lowell, who had dreamed of Planet X meant the name Pluto stuck.
For a good number of years, life with nine planets felt right to the world. By 1931 the Disney character Mickey Mouse had acquired a pup named Pluto (the dog was named for the planet, though the cartoon character is so well known now that many think the planet was named for the dog.) Clyde Tombaugh raked in numerous honors and went back to school for his bachelor’s and masters’ degrees. He founded an astronomy department at New Mexico State University, and continued his work, discovering a comet, a nova, five open clusters, a globular cluster, and a supercluster of galaxies.
Then in 1996, trouble began to brew when a group of scientists put forth the thought that perhaps Pluto wasn’t actually a planet. At the time it was discovered, Pluto was the only known object beyond Neptune in the solar system. Today astronomers have found about 1,000 other small icy objects (and there may be many more) beyond Neptune rotating around the sun, in an area called the Kuiper Belt.
In 2006, the International Astronomical Union decided upon a definition of a “planet”–defined as a round object, orbiting the sun that is gravitationally dominant within its own orbital zone. With this decision, Pluto no longer qualified because its orbital path is different and ranges beyond that of other planets.
Tombaugh Should Still be Recognized
Accomplishments must always be viewed through the lens of the time period in which they occurred. With that in mind, I propose that Clyde Tombaugh, farm boy from Kansas who started out with a homemade telescope, should still be remembered for the remarkable astronomer he turned out to be. The demotion of Pluto in no way should tarnish Clyde Tombaugh’s accomplishment. He did in 1930 what no other scientist had done.