Worked at Lowell Observatory in Flagstaff, Arizona where he served as director from 1916 to 1952. He was a pioneer of spectroscopy, and discovered the rotation and the high radial velocities (in 1912) of those "nebulae" we now know as galaxies. He also discovered the nature of reflection nebulae (also 1912), and investigated planetary atmospheres; e.g., he discovered methane in Neptune's atmosphere, and participated in the search for "Planet X," which resulted in the discovery of Pluto by Clyde W. Tombaugh.
Vesto M. Slipher passed away on August 11, 1969 in Flagstaff, Arizona.
Honors include: Moon Crater Slipher (49.5N, 160.1E, 69 km, in 1970), Mars Crater Slipher (47.8S, 84.6W, 127 km, in 1973), asteroid (1766) Slipher.