Department of Astronomy Center for Radiophysics & Space Research

Phillip D. Nicholson

Professor of Astronomy
Phillip D. Nicholson
Specialty Areas

Planetary Sciences

Research Projects

Cassini Visual Infrared Mapping Spectrometer Team Member, The Irregular Satellite Systems of the Giant Planets., Dynamical Studies of Planetary Rings and Satellites


Philip Nicholson's research centers on two main areas: the orbital dynamics of planetary ring systems and natural satellites, and infrared observational studies of planets, their satellites, and their rings. His work has included studies of the ring systems of Saturn, Uranus, and Neptune via Voyager observations and ground-based stellar occultations; Earth-based observations with the 5-meter Hale Telescope at Palomar of several small moons of Jupiter and Saturn discovered by the Voyager spacecraft; dynamical investigations of the planetary system around the pulsar PSR 1257 + 12, and of the rotational evolution of natural satellites; and studies of the zodiacal dust bands discovered by the Infrared Astronomical Satellite in 1983. Together with colleagues in Canada and at Harvard, he has been involved in the discovery of numerous outer satellites of Uranus, Saturn and Neptune. Nicholson is a member of the Visual Infrared Mapping Spectrometer science team on the NASA/ESA Cassini mission to Saturn, and was the leader of a team of Cornell and Caltech astronomers studying the impact of Comet Shoemaker-Levy 9 into Jupiter in July 1994 using the Hale Telescope. He has served on the Committees on Planetary and Lunar Exploration and on Astronomy and Astrophysics of the National Research Council, time assignment committees for the Kuiper Airborne Observatory and Hubble Space Telescope, and scientific advisory committees for Arecibo and IPAC. He has coauthored review articles on planetary ring dynamics and on the Uranian and Neptunian ring systems.
Infrared images of Comet Shoemaker-Levy 9 bombarding Jupiter
View of prominent impacts
View directly over the South Pole of Jupiter
HST image of Saturn RPX
HST image 2 of Saturn RPX

Selected Publications
  • R.G. French and P.D. Nicholson (2000): "Saturn's Rings II: Particle Sizes Inferred from Stellar Occultation Data."  Icarus 145, 502-523.
  • B. Gladman, J. Kavelaars, M. Holman, P.D. Nicholson, J.A. Burns, C. Hergenrother, J-M. Petit, B.G. Marsden, R. Jacobson, W. Gray, T. Grav (2001): “Discovery of 12 Satellites of Saturn Exhibiting Orbital Clustering.” Nature 412, 163-166.
  • P.D. Nicholson, Richard G. French, Donald B. Campbell, Jean-Luc Margot, Michael C. Nolan, Gregory J. Black, and Heikki J. Salo (2005): “Radar Imaging of Saturn’s Rings.” Icarus 177, 32-62.
  • P.D. Nicholson, M.M. Hedman, R.N. Clark, M.R. Showalter, D.P. Cruikshank, J.N. Cuzzi, G. Filacchione, F. Capaccioni, P. Cerroni, G.B. Hansen et al. (2008): “A close look at Saturn’s rings with Cassini VIMS.” Icarus 193, 182-212.
  • M.M. Hedman, P.D. Nicholson, M.R. Showalter, R.H. Brown, B.J. Buratti, R.N. Clark (2009): “Spectral observations of the Enceladus plume with Cassini-VIMS.” Astrophysical Journal 693, 1749.
  • M.M. Hedman, P.D. Nicholson, K. Baines, B. Buratti, C. Sotin, R.N. Clark, R.H. Brown, R. French, E. Marouf (2010) : “The Architecture of the Cassini Division.” Astronomical Journal 139, 228-251.
  • P.D. Nicholson and M.M. Hedman (2010): “Self-gravity wake parameters in Saturn’s A and B rings.” Icarus 206, 410-423.