ALS, one page, 8.5 x 11, New Mexico State University letterhead, November 13, 1989. Letter to John Adams, in full: "Pluto's mass is only 1/400th that of the Earth—a far cry from Lowell's predicted 7 Earth-masses, which he called 'Planet X.' From 1929-1943, I thoroughly searched 2/3rds of the entire sky to the 17th magnitude (about 5 times fainter than Pluto at mean distance) and found no other planets brighter than Pluto. Consequently, I would assert that 'Planet X' does not exist. I think that the Shuttle development was well worth it, because it will be a convenient transport whenever a space lab is set up in orbit. The logistics and high costs will probably limit manned space-flights beyond Mars." In fine condition.
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