Dr. Bill Sheehan is co-author, with Dale Cruikshank, of Discovering Pluto: exploration at the edge of the Solar System. He began to correspond with Clyde Tombaugh in 1985, met him in 1991, and plans (with Kevin Schindler) to write up Clyde’s many important contributions to planetary astronomy apart from Pluto.  He wears the same hat size as Percival Lowell.