Friends and colleagues of the late Clyde Tombaugh, discoverer of Pluto, had this to say Friday about the International Astronomical Union’s decision to reclassify Pluto as a “dwarf planet”: Don’t rewrite the textbooks yet.

“Why not? Because the debate is not over,” New Mexico State University astronomer Bernie McNamara told a high-spirited group of Pluto supporters outside the university’s Zuhl Library.

McNamara joined about 50 NMSU students and staff members — some wearing T-shirts and carrying signs saying “Protest for Pluto – Size Doesn’t Matter” — for a good-natured challenge of the IAU vote. Patsy Tombaugh, the famed astronomer’s widow, and their son Al Tombaugh also participated.

McNamara noted the IAU had been considering a different set of criteria for defining what a planet is — criteria that would have expanded the number of planets from nine to 12 — shortly before the Aug. 24 vote was taken. “But things changed” within the planetary definition committee, which came up with new criteria that had the effect of demoting Pluto, and only about 400 of the IAU’s thousands of members were present when the vote was taken, he said.

“This was not a statement by the astronomical community at large,” he said, adding that a petition opposing the IAU definition of a planet is now circulating among the world’s planetary scientists and astronomers.

Herb Beebe, professor emeritus of astronomy and a longtime colleague of Tombaugh’s, suggested tongue in cheek that the definition of a planet made about as much sense as the definition of continents on Earth. “Look at a map — what’s with Europe and Asia?” he said. “I say let’s eliminate Europe.”

Beebe said the commonly repeated story of Tombaugh’s early career — that he was a farm boy with an interest in astronomy whose drawings of Mars landed him a job at Lowell Observatory — is a little off the mark.

“He was not a novice,” Beebe said after tracing some of the young Tombaugh’s achievements. “He might have been an amateur astronomer but he was not a novice. He was a hardworking young man with a lot of training who helped re-invigorate a program that was in bad shape.”

Tombaugh was 24 years old when he discovered Pluto at Lowell Observatory in 1930. “It took 60 years and an accumulation of astronomers” using more advanced technology to find the next solar system object similar to Pluto, Beebe said.

“Clyde Tombaugh was an American hero,” he said. “For that reason alone, Pluto’s status as a full-fledged planet should be kept.”

Tombaugh came to NMSU in 1955 and developed a world-class astronomy research program. He officially retired as a professor emeritus in 1973 but he continued to be active as a lecturer for many years after that.

Following his death in 1997, at the age of 90, Tombaugh’s family donated his papers to the university. The papers are archived in NMSU’s Branson Library, Archives and Special Collections.