American astronomer who studied the structure of the Milky Way Galaxy and helped determine the shape of our galaxy. As a graduate student at Yerkes Observatory he worked under William Morgan with fellow graduate student Don Osterbrock. In 1952, they published their observations that demonstrated the spiral structure of the Milky Way by estimating the distances to HII regions and young hot stars. For a while Sharpless was at Mount Wilson Observatory where he worked on galaxy photography with Walter Baade and Edwin Hubble.
In 1953 Sharpless joined the staff of the US Naval Observatory in Flagstaff, Arizona. Here he surveyed and cataloged HII regions of the Milky Way Galaxy using the images from the Palomar Sky Survey. From this work Sharpless published his catalog of HII regions in two editions, the first in 1953 with 142 nebula. The second and final edition was published in 1959 with 313 nebula.
Stewart Sharpless is currently a retired professor emeritus at Rochester University.