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Statement from NMSU Astronomy Department head regarding reclassification of Pluto

EDITOR'S NOTE: Clyde Tombaugh, who discovered Pluto in 1930 at the age of 24, joined New Mexico State University in 1955 and remained active long after his retirement as a professor emeritus in 1973, lecturing on an occasional basis and going to his office regularly. Tombaugh died on Jan. 17, 1997, at the age of 90. Jim Murphy, a planetary scientist and head of the NMSU Astronomy Department, today prepared the following statement regarding a decision by the International Astronomical Union to reclassify Pluto into a new category of "dwarf planets":


ternational Astronomical Union membership in attendance at a meeting in Prague, Czech Republic, has voted upon and approved a definition of the term 'planet' that excludes Pluto from a position it has held since its discovery 76 years ago, in 1930. This new planet definition excludes Pluto from the family of significant planets because Pluto has not 'swept clean' its portion of the solar system, though Pluto does meet other definition criteria by orbiting the sun and by being massive enough to overcome its own material strength and gravitationally pull itself into a spherical shape.

"This reclassification of Pluto as a 'dwarf planet' does not in any way change the physical aspects of Pluto. More importantly, this reclassification does not minimize the tremendous astronomical work that Clyde Tombaugh and his Lowell Observatory colleagues conducted leading up the 1930 discovery. In fact, this reclassification indicates how 'ahead of its time' Pluto's initial detection actually was. A greater than 60-year time interval was required for another Pluto-like object to be detected in that distant realm of our solar system, and it was 73 years before a comparable sized object was discovered, using technology that was greatly enhanced over that available in 1930.

"The NMSU Department of Astronomy is and always will be proud of its history with Clyde Tombaugh, and his family, and will always hold his accomplishments in the highest esteem. Long live Pluto and its sibling 'dwarf planets'!"

Jim Murphy
Associate Professor and Department Head
NMSU Department of Astronomy
Aug. 24, 2006