Question: Percival Lowell established the observatory after what American astronomer that discovered Pluto in 1930?
Sentence (from "Tombaugh Cliffs"): Tombaugh Cliffs ( ) is a group of ice-free cliffs which stand at the north side of the mouth of Pluto Glacier and face towards the George VI Ice Shelf which occupies George VI Sound, on the east side of Alexander Island, Antarctica.
Relevant evidence: No