Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine-and-a-half times that of Earth. It has only one-eighth the average density of Earth, but is over 95 times more massive. Even though Saturn is nearly the size of Jupiter, Saturn has less than one-third of Jupiter's mass. Saturn orbits the Sun at a distance of 9.59 AU (1,434 million km) with an orbital period of 29.45 years.
Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System, with a surface area that is comparable to the area of Australia. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. Rhea has a nearly circular orbit around Saturn, but it is also tidally locked, like Saturn's other major moons; that is, it rotates with the same period it revolves (orbits), so one hemisphere always faces towards the planet.
Cassini–Huygens, commonly called Cassini, was a space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit, where it stayed from 2004 to 2017. The two craft took their names from the astronomers Giovanni Cassini and Christiaan Huygens.
Phoebe is the most massive irregular satellite of Saturn with a mean diameter of 213 km (132 mi). It was discovered by William Henry Pickering on 18 March 1899 from photographic plates that had been taken by DeLisle Stewart starting on 16 August 1898 at the Boyden Station of the Carmen Alto Observatory near Arequipa, Peru. It was the first natural satellite to be discovered photographically.
Steven Jeffrey Ostro was an American scientist specializing in radar astronomy. He worked at NASA's Jet Propulsion Laboratory. Ostro led radar observations of numerous asteroids, as well as the moons of Jupiter and Saturn, Saturn's rings, and Mars and its satellites. As of May 2008, Ostro and his collaborators had detected 222 near-Earth asteroids, including 130 potentially hazardous objects and 24 binaries, and 118 main belt objects with radar.
The rings of Saturn are the most extensive and complex ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirely of water ice, with a trace component of rocky material. There is still no consensus as to their mechanism of formation. Although theoretical models indicated that the rings were likely to have formed early in the Solar System's history, newer data from Cassini suggested they formed relatively late.
Carolyn C. Porco is an American planetary scientist who explores the outer Solar System, beginning with her imaging work on the Voyager missions to Jupiter, Saturn, Uranus and Neptune in the 1980s. She led the imaging science team on the Cassini mission in orbit around Saturn. She is an expert on planetary rings and the Saturnian moon, Enceladus.
Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust.
Peter H. Schultz is Professor of Geological Sciences at Brown University specializing in the study of planetary geology, impact cratering on the Earth and other objects in the Solar System, and volcanic modifications of planetary surfaces. He was co-investigator to the NASA Science Mission Directorate spacecraft Deep Impact and the Lunar Crater Observation and Sensing Satellite (LCROSS). He was awarded the Barringer Medal of the Meteoritical Society in 2004 for his theoretical and experimental studies of impact craters.
S/2009 S 1 is a moonlet embedded in the outer part of Saturn's B Ring, orbiting 117,000 km (73,000 mi) away from the planet. The moonlet was discovered by the Cassini Imaging Team during the Saturnian equinox event on 26 July 2009, when the Cassini spacecraft imaged the moonlet casting a 36 km (22 mi)-long shadow onto the B Ring. With a diameter of 300 m (1,000 ft), it is most likely a long-lived solid body, which would count it as the smallest and innermost known moon of Saturn.
Reta F. Beebe is an American astronomer, author, and popularizer of astronomy. She is an expert on the planets Jupiter and Saturn, and the author of Jupiter: The Giant Planet. She is a professor emeritus in the Astronomy Department at New Mexico State University and 2010 winner of the NASA Exceptional Public Service medal.
Mark Robert Showalter is a senior research scientist at the SETI Institute. He is the discoverer of six moons and three planetary rings. He is the Principal Investigator of NASA's Planetary Data System Rings Node, a co-investigator on the Cassini–Huygens mission to Saturn, and works closely with the New Horizons mission to Pluto.
A subsatellite, also known as a submoon or a moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet.
The Day the Earth Smiled is a composite photograph taken by the NASA spacecraft Cassini on July 19, 2013. During an eclipse of the Sun, the spacecraft turned to image Saturn and most of its visible ring system, as well as Earth and the Moon as distant pale dots. The spacecraft had twice taken similar photographs in its previous nine years in orbit around the planet. The name also refers to the activities associated with the event, as well as to the photographic mosaic created from it.
The Cassini space probe was deliberately disposed of via a controlled fall into Saturn's atmosphere on September 15, 2017, ending its nearly two-decade-long mission. This method was chosen to prevent biological contamination of any of the moons of Saturn now thought to offer potentially habitable environments. Factors that influenced the mission end method included the amount of rocket fuel left, the health of the spacecraft, and funding for operations on Earth.
Amanda R. Hendrix is an American planetary scientist known for her pioneering studies of solar system bodies at ultraviolet wavelengths. She is a senior scientist at the Planetary Science Institute. Her research interests include moon and asteroid surface composition, space weathering effects and radiation products. She is a co-investigator on the Cassini UVIS instrument, was a co-investigator on the Galileo UVS instrument, is a Participating Scientist on the Lunar Reconnaissance Orbiter LAMP instrument and is a Principal Investigator on Hubble Space Telescope observing programs. As of 2019, she is also the co-lead of the NASA Roadmaps to Oceans World Group.
Henry B. Throop, is an American astronomer and planetary scientist who specializes in the dynamics of rings and dust in the outer solar system. Throop is a member of the science team for NASA's New Horizons mission to Pluto and the Kuiper Belt, and has been involved with NASA missions throughout the solar system. Throop lives in Washington, DC where he runs NASA's science programs in the outer solar system. He has done extensive education and outreach around the world, having spent nearly a decade as an astronomer living in South Africa, India, and Mexico. The asteroid 193736 Henrythroop is named after him.
Sarah Hörst is an associate professor of planetary sciences at Johns Hopkins University, who focuses on understanding planetary atmospheric hazes, in particular the atmosphere of Saturn's moon Titan.
Carrie Anderson is an American planetary scientist at NASA's Goddard Space Flight Center.
Candice Joy Hansen-Koharcheck is a planetary scientist. She is responsible for the development and operation of the JunoCam, for which she received the NASA's Outstanding Public Leadership Medal in 2018.
