American astronomer (1906–1997) best known for discovering Pluto in 1930. ALS, one page, 8.5 x 11, New Mexico State University letterhead, October 27, 1980. Tombaugh writes to Jerry Granat. In part: “The idea of Pluto not being a major planet is unjustified. Even with the latest estimates of size, Pluto is at least as large as the moon, which in turn is 4 times the diameter of the largest known asteroid. Apparently, the reporter of the article ‘that Pluto is—merely another star in the sky’ does not know the difference between a star and a planet. Stars are self-luminous, planets are not. The orbital motion of Pluto indicates or proves that Pluto is a member planet of the solar system.” Earlier this year, the Pluto-as-planet controversy was reopened with discussions to reclassify the entity as a “dwarf planet,” or, less felicitously, “trans-Neptunian object.” Accompanied by the original mailing envelope and unsigned copies of Granat’s letters to Tombaugh. In fine condition. R&R COA. From the Jerry Granat collection.
