Steven Soter is an astrophysicist currently holding the positions of scientist-in-residence for New York University's Environmental Studies Program and of Research Associate for the Department of Astrophysics at the American Museum of Natural History. He is a vocal proponent of the International Astronomical Union's controversial 2006 definition of planet.
Soter received his Bachelors degree in astronomy and physics from UCLA in 1965 and his doctorate in astronomy from Cornell University. One of his advisors was popular astronomer Carl Sagan.
In 1974, Soter suggested that dust produced by meteoritic bombardment of Saturn's moon Phoebe might orbit the planet until colliding with Saturn's moon Iapetus and be responsible for the unique dark-bright dichotomy of the latter. Although not the unique cause, dust originating from Saturn's irregular satellites was later found in data from the Cassini spacecraft to indeed play a crucial role in the coloration of Iapetus. The discovery of Saturn's "Phoebe ring" in 2009 further strengthened the probability that this process first described by Soter plays a significant role in shaping Iapetus's appearance.