Hyrrokkin or Saturn XLIV 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'' ...

of Saturn. 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,

Jan Kleyna Jan T. Kleyna is a postdoctoral astronomy researcher at the University of Hawai'i A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities t ...

, and Brian G. Marsden on June 26, 2006, from observations taken between December 12, 2004, and April 30, 2006. Hyrrokkin is about 8 kilometres in diameter, and orbits Saturn at an average distance of 18,168 Mm in 914 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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 153° 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 agains ...

(154° 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-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.3582. During four observations in March 2013, the synodic rotational period was measured by the

Cassini spacecraft Cassini may refer to: People * Cassini (surname) * Oleg Cassini (1913-2006), American fashion designer :Cassini family: * Giovanni Domenico Cassini (1625–1712), Italian mathematician, astronomer, engineer, and astrologer * Jacques Cassini (1 ...

to approximately 12 hours and 45 minutes. The rotation period was later refined to hours. Its light curve shows three minima as seen in

Ymir In Norse mythology, Ymir (, ), also called Aurgelmir, Brimir, or Bláinn, is the ancestor of all jötnar. Ymir is attested in the ''Poetic Edda'', compiled in the 13th century from earlier traditional material, in the ''Prose Edda'', writ ...

and Siarnaq, but has one minimum much shallower than the others. The rotation period and orbit are similar to Greip's, with only the

being appreciably different, but it is not known whether the moons are closely related to each other. It was named in April 2007 after

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 re ...

, a giantess from Norse mythology, who launched

Hringhorni In Norse mythology, ''Hringhorni'' (Old Norse "ship with a circle on the stem"Simek (2007:159).) is the name of the ship of the god Baldr, described as the "greatest of all ships". Mythology According to ''Gylfaginning'', following the murder ...

, Baldr's funeral ship. It was originally listed as being spelled ''Hyrokkin'', but the spelling was later corrected.

References

External links

Scott Sheppard's Saturnian satellites page

June 30, 2006 (discovery)

June 26, 2006 (discovery and ephemeris)

April 5, 2007 (Naming the moon)

July 31, 2007 (correcting the name)
Denk, T., Mottola, S. (2013): Irregular Saturnian Moon Lightcurves from Cassini-ISS Observations: Update. Abstract 406.08DPS conference 2013
Denver (Colorado), October 10, 2013 (synodic rotation period)
{{Moons of Saturn, state=uncollapsed Moons of Saturn Norse group Irregular satellites Discoveries by Scott S. Sheppard Astronomical objects discovered in 2006 Moons with a retrograde orbit