Percival Low-
ell, a wealthy Bostonian, to carry out the search.
A 1950 estimate the Palomar Observatory's Gerard Kuiper put
Pluto's diameter at 3,800 miles, about half that of the Earth. A 1965
experiment that measured the time Pluto took to cross a star of known
size narrowed the estimate to a maximum of 3,600 miles. When another
"occultation" took place on Easter Sunday 1980, a new measurement
technique allowed astronomers to fix the diameter at 2,500 miles-
barely larger than...