American astronomer, Clyde Tombaugh (1906-1997) is most famous for discovering the planet Pluto in 1930. During his career he also discovered many asteroids, variable stars, star clusters, galaxy clusters and a galaxy supercluster.
This is an original sketch by Clyde Tombaugh showing the orbit of Pluto in comparison to the orbits of Earth, Saturn and Neptune.
The pencil sketch has been drawn on a sheet of off-white card measuring 5½" x 7½". There are several compass holes in the card but it is otherwise in fine condition.
Tombaugh has titled the sketch "SOLAR SYSTEM" and has signed and inscribed "Drawn by Clyde Tombaugh, 18 Sept 1990" below the title.