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.{{Cite journal | title = Formation of Iapetus' Extreme Albedo Dichotomy by Exogenically Triggered Thermal Ice Migration In 1977-1979, Soter co-wrote, along with Carl Sagan and
Ann Druyan, Carl Sagan's monumental 1980 astronomy documentary series
Cosmos. Since then, he has also acted as advisor on a number of science documentaries, such as the IMAX films
Blue Planet and
Cosmic Voyage. In 1997, Soter took a position at the
American Museum of Natural History's
Hayden Planetarium, and eventually progressed to the position of research associate. He also made significant contributions to research related to the ancient Greek city
Helike. In 2007, after the IAU voted on a
definition of planet, Soter published an article in
Scientific American in which he outlined a mathematical formulation, the "planetary discriminant," to describe how the IAU's requirement that a planet must have "
cleared its neighborhood" of other objects might be applied in practice. He had already written a more technical article on the same subject in 2006, submitted to
The Astronomical Journal before the IAU resolution. In 2014, he partnered with Druyan again to co-write a new television miniseries,
Cosmos: A Spacetime Odyssey, hosted by his AMNH colleague
Neil deGrasse Tyson. ==References==