Philip D. Nicholson (born 1951) is an Australian-born professor of astronomy at Cornell University in the Astronomy department specialising in Planetary Sciences. He has been editor-in-chief of the journal Icarus since 1998. [1]
Nicholson received his Ph.D. from Caltech in 1979. Nicholson's research centers on two main areas: orbital dynamics in planetary ring systems 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 Observatory 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, [2] 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. [3] [4] [5]
Nicholson was a member of the Visual Infrared Mapping Spectrometer science team on the NASA/ESA Cassini–Huygens 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.
The inner main-belt asteroid 7220 Philnicholson, discovered by Edward Bowell at Anderson Mesa in 1981, was named in his honor. [1] The official naming citation was published on 5 October 1998 ( M.P.C. 32790 ). [6]
Nicholson won the Harold Masursky Award in 2019, "for meritorious service to planetary science" in his role as editor-in-chief of Icarus. [7]
He was elected a Legacy Fellow of the American Astronomical Society in 2020. [8]
Uranus is the seventh planet from the Sun and is a gaseous cyan ice giant. Most of Uranus is made out of water, ammonia, and methane in a supercritical phase of matter, which in astronomy is called 'ice' or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of 49 K out of all Solar System's planets. Uranus has a marked axial tilt of 97.8° with a retrograde rotation rate of 17 hours. This means that in an 84 Earth years orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness.
Cordelia is the innermost known moon of Uranus. It was discovered from the images taken by Voyager 2 on January 20, 1986, and was given the temporary designation S/1986 U 7. It was not detected again until the Hubble Space Telescope observed it in 1997. Cordelia takes its name from the youngest daughter of Lear in William Shakespeare's King Lear. It is also designated Uranus VI.
Juliet is an inner satellite of Uranus. It was discovered from the images taken by Voyager 2 on 3 January 1986, and was given the temporary designation S/1986 U 2. It is named after the heroine of William Shakespeare's play Romeo and Juliet. It is also designated Uranus XI.
Caliban is the second-largest retrograde irregular satellite of Uranus. It was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope together with Sycorax and given the temporary designation S/1997 U 1.
Themisto, also known as Jupiter XVIII, is a small prograde irregular satellite of Jupiter. It was discovered in 1975, subsequently lost, and rediscovered in 2000.
Setebos is one of the outermost retrograde irregular satellites of Uranus. It was discovered on 18 July 1999 by John J. Kavelaars et al. and provisionally designated S/1999 U 1.
Sycorax is the largest irregular satellite of Uranus. Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale telescope, together with Caliban, and given the temporary designation S/1997 U 2.
Kiviuq is a prograde irregular satellite of Saturn. It was discovered by J. J. Kavelaars in 2000, and given the temporary designation S/2000 S 5. It was named after Kiviuq, a hero of Inuit mythology.
Ijiraq, or Saturn XXII (22), is a small prograde irregular satellite of Saturn. It was discovered by the team of Brett Gladman, John J. Kavelaars, et al. in 2000, and given the temporary designation S/2000 S 6. It was named in 2003 after the ijiraq, a creature in Inuit mythology.
Paaliaq is a prograde irregular satellite of Saturn. It was discovered by J. J. Kavelaars, Brett J. Gladman, Jean-Marc Petit, Hans Scholl, Matthew J. Holman, Brian G. Marsden, Philip D. Nicholson and Joseph A. Burns in early October 2000, and given the temporary designation S/2000 S 2. It was named in August 2003 after a fictional shaman in the book The Curse of the Shaman, written by Michael Kusugak, who supplied Kavelaars with the names of giants from Inuit mythology that were used for other Saturnian moons.
Skathi, also named Saturn XXVII and originally spelled Skadi, is a natural satellite of the planet Saturn. Skathi is one of Saturn's irregular moons, in its Norse group of satellites. It was discovered on September 23, 2000, by a team of astronomers led by Brett Gladman. The team announced their discovery on December 7, 2000, along with seven other satellites of Saturn, namely; Tarvos, Ijiraq, Thrymr, Siarnaq, Mundilfari, Erriapus, and Suttungr. The moon was named after Skaði, a figure in Norse mythology, as part of an effort to diversify the largely Greek and Roman names of astronomical objects.
Erriapus, or Saturn XXVIII (28), is a prograde irregular satellite of Saturn. It was discovered by Brett Gladman, John J. Kavelaars and colleagues in 2000, and given the temporary designation S/2000 S 10. It was named Erriapo in August 2003 after Erriapus, a giant in Gaulish mythology; the name was changed from dative Erriapo to nominative Erriapus per IAU conventions in late 2007.
Siarnaq, also designated Saturn XXIX, is a prograde irregular satellite of Saturn. It was discovered at the Mauna Kea Observatory by astronomers Brett Gladman and John Kavelaars in 2000, and given the temporary designation S/2000 S 3. It was named after Siarnaq, more widely known as Sedna, the Inuit goddess of the sea, and is the largest member of Saturn's Inuit group of irregular satellites.
Tarvos, or Saturn XXI, is a prograde irregular satellite of Saturn. It was discovered by John J. Kavelaars et al. on September 23, 2000, and given the temporary designation S/2000 S 4. The name, given in August 2003, is after Tarvos, a deity depicted as a bull god carrying three cranes alongside its back from Gaulish mythology.
Stephano is a retrograde irregular satellite of Uranus. It was discovered by Brett J. Gladman, et al. in 1999, and given the provisional designation S/1999 U 2.
Uranus, the seventh planet of the Solar System, has 27 known moons, most of which are named after characters that appear in, or are mentioned in, the works of William Shakespeare and Alexander Pope. Uranus's moons are divided into three groups: thirteen inner moons, five major moons, and nine irregular moons. The inner and major moons all have prograde orbits, while orbits of the irregulars are mostly retrograde.
The planet Neptune has 14 known moons, which are named for minor water deities in Greek mythology. By far the largest of them is Triton, discovered by William Lassell on October 10, 1846, 17 days after the discovery of Neptune itself. Over a century passed before the discovery of the second natural satellite, Nereid. Neptune's outermost moon Neso, which has an orbital period of about 27 Julian years, orbits farther from its planet than any other moon in the Solar System.
The Gallic group is a dynamical grouping of the prograde irregular satellites of Saturn following similar orbits. Their semi-major axes range between 16 and 19 Gm, their inclinations between 35° and 40°, and their eccentricities around 0.53.
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape as Triton is a round moon, but is considered irregular due to its orbit.
Joseph Burns is a professor at Cornell University with a dual appointment in the Sibley School of Mechanical and Aerospace Engineering (MAE) and the Astronomy department. His primary area of research is dynamics in planetary sciences.