Back in 1930, the Lowell Observatory in Flagstaff's young hire Clyde Tombaugh had already spent more than a year of painstakingly difficult and detailed work studying photos of the night sky for things that moved. Other researchers dropped out after the tedium proved unrewarding. One visiting astronomer even told Tombaugh, "Young man, you are wasting your time. If there are any more planets to be found, they would have been found long before this."

Thanks to many scientists' hunger for knowledge along with remarkable advances in hardware and technology, what we know of worlds beyond the earth is rapidly changing, especially in recent years.

The discovery of the Kuiper Belt in 1992 greatly expanded our knowledge of our solar system. That's where Pluto is found along with thousands of other objects. In 2003 an ice dwarf 20 percent bigger than Pluto, called Xena, was found along with her own moon Gabrielle. In June 2005 it was announced that Pluto itself was found to have two more moons than previously known. In December 2005 word came that Uranus also has additonal moons. Additionally, and perhaps eventually more exciting in our search for life beyond Earth, more than 160 planet-like objects outside our solar system have already been found!

All this new space real estate has reopened the question of what constitutes a planet. Until now, there has been no formally accepted definition. The International Astronomical Union has been struggling for two years to agree one. One proposal is "any round object larger than 1000 kilometers (625 miles) across that orbits the sun" which would certainly include Pluto.

Ultimately, no re-examination of Pluto now can degrade the accomplishment of Dr. Tombaugh's discovery in 1930. It was an extraordinary achievement then and remains so today.

(source: "Clyde Tombaugh and the search for Planet X" by M. Wetterer, Carolrhoda Books, Inc., 1996, also "Discoveries quickly changing astonomy" by Robert S. Boyd, Knight Ridder Newspapers, 2005)