Pluto Is an Exceedingly Minor Planet

SINCE his discovery, the planet Pluto has been a good deal of a disappointment to his sponsors. Now [1934] Dr. Baade, of Mt. Wilson observatory, estimates that Pluto’s mass is something like that of Titan, the largest satellite of Saturn. But the mass of Titan, though the diameter is 2,600 miles, is but l/50th that of the Earth, or less than twice that of the moon. So that Pluto ranks as the largest asteroid, rather than the smallest planet; and it may be necessary to look farther for unknown planets.

But the 1934 estimate was still wrong. The real mass of Pluto is only ~1/450th of the Earth! https://t.co/KvmktwvfZ5

— Mike Brown (@plutokiller) May 5, 2015

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Also see Pluto’s killer speaks.