ALS, one page, 8.5 x 11, February 20, 1990. Interesting letter about Pluto, in part: "Referring to the photograph of the discovery sections of Pluto (about the size of a postage stamp from the 14 by 17 inch original plates), Pluto is not Lowell's Planet X. You may like to see the article 'Where is Planet X?' in the December 1989 issue of Sky & Telescope…From my thorough extensive planet search to the 17th magnitude over 2/3rds of the entire sky, no Planet X ever showed up, supposed to equal 6.7 Earth-masses. Pluto has only 1/400th of the mass of the Earth." In fine condition.
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