Gerd (moon)

Last updated
Gerd
Discovery [1]
Discovered by Sheppard et al.
Discovery date2019
Designations
Named after
Gerðr
Saturn LVII
S/2004 S 25
S8631e [2]
Orbital characteristics [2]
20544500 km
Eccentricity 0.457
−1095.0 days
Inclination 173.3°
Satellite of Saturn
Group Norse group
Physical characteristics
4+50%
−30%
 km
25.2

    Gerd (Saturn LVII), provisionally known as S/2004 S 25, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 22, 2007. [3] It was given its permanent designation in August 2021. [4] On 24 August 2022, it was officially named after Gerðr, a jötunn from Norse mythology. [5] She is married to Freyr and the personification of fertile soil. [6]

    Gerd is about 4 kilometres in diameter, and orbits Saturn at an average distance of 21.174 Gm in 1150.69 days, at an inclination of 173° to the ecliptic, in a retrograde direction and with an eccentricity of 0.442. [3]

    Related Research Articles

    The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery, identified through its various designations, and the discoverer(s) listed.

    <span class="mw-page-title-main">Moons of Saturn</span> Natural satellites of the planet Saturn

    The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the solar system. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System, with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.

    <span class="mw-page-title-main">Siarnaq</span> Moon of Saturn

    Siarnaq, also designated Saturn XXIX, is the second-largest irregular moon of Saturn. It was discovered on 23 September 2000 by a team of astronomers led by Brett J. Gladman. It was named after the Inuit goddess of the sea, Siarnaq, who is more commonly known as Sedna. Siarnaq is the largest member of Saturn's Inuit group of prograde irregular moons, which orbit far from Saturn in the same direction as the planet's rotation. The moons of the Inuit group are believed to have originated as fragments from the collisional breakup of a larger progenitor moon after it was gravitationally captured into orbit around Saturn several billion years ago. Several other small Inuit group moons share similar orbits to Siarnaq, indicating that the moon had experienced another collision after forming from its progenitor.

    Scott Sander Sheppard is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System.

    S/2004 S 7 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 4 May 2005 from observations taken between 12 December 2004 and 8 March 2005.

    S/2004 S 12 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 4 May 2005 from observations taken between 12 December 2004 and 9 March 2005.

    <span class="mw-page-title-main">Norse group</span> Category of satellites of Saturn

    The Norse group is a large group of retrograde irregular satellites of Saturn. Their semi-major axes range between 12 and 27 Gm, their inclinations between 136° and 178° and their eccentricities between 0.06 and 0.63. Unlike the Inuit and Gallic groups, the orbital parameters are widely dispersed and the group is likely to be composed from a number of subgroups with more homogeneous orbital and physical parameters. The International Astronomical Union (IAU) reserves names taken from Norse mythology for these moons. The exception is Phoebe, the largest, which was discovered long before the others.

    Gridr, originally known as S/2004 S 20, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 22, 2007. It was given its permanent designation in June 2021. On 24 August 2022, it was officially named after Gríðr, a jötunn in Norse mythology. She is the mother of Víðarr the silent and the consort of Odin. She warned Thor about the treachery of Geirröðr and equipped him with her belt of strength, her iron glove, and her staff Gríðarvöl (Gríðr's-staff).

    Angrboda, provisionally known as S/2004 S 22, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and February 1, 2006. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Angrboða, a jötunn in Norse mythology. She is the consort of Loki and the mother of the wolf Fenrir, the Midgard serpent Jörmungandr, and the ruler of the dead Hel.

    Skrymir, provisionally known as S/2004 S 23, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 22, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Útgarða-Loki. He is a jötunn from Norse mythology and master of illusions.

    S/2004 S 24 is a natural satellite of Saturn, and the outermost known prograde satellite. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 22, 2007.

    Saturn LVIII, provisionally known as S/2004 S 26, is the outermost numbered natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 21, 2007. It was given its permanent designation in August 2021.

    Eggther, provisionally known as S/2004 S 27, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 21, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Eggþér, a jötunn from Norse mythology. He is the herder of the female jötunn who lives in Járnviðr (Ironwood) and raises monstrous wolves. In the poem Völuspá, Eggþér is described as sitting on a mound and joyfully striking his harp while the red rooster Fjalarr begins to crow to herald the onset of Ragnarök.

    Saturn LX, provisionally known as S/2004 S 29, is a natural satellite of Saturn and a member of the Gallic group. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and January 17, 2007. It was given its permanent designation in August 2021.

    Beli, provisionally known as S/2004 S 30, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019, from observations taken between December 12, 2004, and March 21, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was named after Beli, a jötunn from Norse mythology. He is killed by Freyr with the antler of a hart (stag). According to John Lindow, the myth of Beli is partially lost. Some scholars suggest that he may be the brother of Freyr's wife Gerðr, although this is uncertain.

    Gunnlod, provisionally known as S/2004 S 32, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 8, 2019 from observations taken between December 12, 2004 and January 19, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Gunnlǫð, a jötunn from Norse mythology. She is the daughter of Suttungr and guarded the mead of poetry for him. But Odin in the form of a snake gained access to the chamber in Hnitbjorg where the mead was kept, seduced Gunnlǫð, and slept with her for three nights. In return Gunnlǫð allowed Odin three drinks of the mead, and he then immediately flew out of the cavern in the form of an eagle.

    Thiazzi, provisionally known as S/2004 S 33, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 8, 2019 from observations taken between December 12, 2004 and March 22, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Þjazi, a jötunn from Norse mythology. He is a son of Alvaldi and kidnapped the goddess Iðunn, who guarded the apples of the gods.

    Saturn LXIV, provisionally known as S/2004 S 34, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 8, 2019, from observations taken between December 12, 2004, and March 21, 2007. It was given its permanent designation in August 2021.

    Alvaldi, provisionally known as S/2004 S 35, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 8, 2019 from observations taken between December 12, 2004 and February 25, 2006. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Alvaldi, a jötunn from Norse mythology. He was very rich in gold, and when he died his sons divided his inheritance by taking a mouthful each.

    Geirrod, provisionally known as S/2004 S 38, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 8, 2019 from observations taken between December 12, 2004 and March 22, 2007. It was given its permanent designation in August 2021. On 24 August 2022, it was officially named after Geirröðr, a jötunn from Norse mythology. He is an enemy of Thor and is killed by him.

    References

    1. Discovery Circumstances from JPL
    2. 1 2 S.S. Sheppard (2019), Moons of Saturn, Carnegie Science, on line
    3. 1 2 "MPEC 2019-T132 : S/2004 S 25". minorplanetcenter.net. Retrieved 7 October 2019.
    4. "M.P.C. 133821" (PDF). Minor Planet Center. International Astronomical Union. 10 August 2021. Retrieved 21 August 2021.
    5. "Names Approved for 10 Small Satellites of Saturn". usgs.gov. USGS. 24 August 2022. Retrieved 30 August 2022.
    6. "Planet and Satellite Names and Discoverers". usgs.gov. IAU WGPSN. Retrieved 30 August 2022.