Greip or Saturn LI is a

natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are often colloquially referred to as ''moons'' ...

Saturn 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; h ...

. Its discovery was announced by

Scott S. Sheppard Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System. He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Scie ...

David C. Jewitt David Clifford Jewitt (born 1958) is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Pl ...

Jan Kleyna Jan T. Kleyna is a postdoctoral astronomy researcher at the University of Hawai'i Institute for Astronomy. His area of interest is galaxy dynamics, and he has worked to develop codes for the real-time detection of moving objects such as Jovian ...

, and

Brian G. Marsden Brian Geoffrey Marsden (5 August 1937 – 18 November 2010) was a British astronomer and the longtime director of the Minor Planet Center (MPC) at the Center for Astrophysics Harvard & Smithsonian (director emeritus from 2006 to 2010). ...

on 26 June 2006, from observations taken between 5 January and 1 May 2006. Greip is about 6 kilometres in diameter, and orbits Saturn at an average distance of 18,066 Mm in 906.556 days, at an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 172.7° to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...

(159.2° to Saturn's equator), in a retrograde direction and with an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.3735, and is presumably at high risk of eventually colliding with Phoebe. It is unknown whether Greip is more similar to

Suttungr In Norse mythology, Suttungr ( ; Old Norse: ) was a ''jötunn'' and the son of Gilling. Mythology Suttungr searched for his parents and threatened the dwarven brothers Fjalar and Galar who had killed them, tying them and some other dwarves wh ...

Hyrrokkin Hyrrokkin (Old Norse: ) is a female jötunn in Norse mythology. According to 13th-century poet Snorri Sturluson, she launched the largest of all ships at Baldr's funeral after the Æsir gods were unable to budge the vessel. Hyrrokkin was a relat ...

in color. Its rotation period is most likely hours with two minima in the light curve, but a longer period of 19 hours cannot be ruled out due to the short observation time by ''

Cassini–Huygens ''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space research, 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, i ...

''. It is named after Greip, a giantess in

Norse mythology Norse, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period ...

References

Institute for Astronomy Saturn Satellite Data

June 30, 2006 (discovery)

June 26, 2006 (discovery and ephemeris)

September 20, 2007 (naming) {{DEFAULTSORT:Greip (Moon) Norse group Moons of Saturn Irregular satellites Discoveries by Scott S. Sheppard Astronomical objects discovered in 2006 Moons with a retrograde orbit