Norse group

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 (mostly giants) for these moons. The exception is Phoebe (Greek mythology), the largest, which was discovered long before the others.

Diagram illustrating the orbits of the irregular satellites of Saturn, with major groups and moons labeled. The inclination and semi-major axis are represented on the Y and X-axis, respectively. The satellites with inclinations below 90° are prograde, those above 90° are retrograde. The X-axis is labeled in terms of Saturn's Hill radius.

The discovery of 17 new moons in this group was announced in October 2019. A team led by Scott S. Sheppard using the Subaru Telescope at Mauna Kea discovered 20 new moons, each about 5 kilometres (3.1 miles) in diameter. 17 of these are thought to fit into the Norse group. One of these is the most distant moon of Saturn. A public naming contest for these moons was announced, restricted to names from Norse mythology.^[1] Ten of these moons received official names in August 2022.^[2]

The members of the group are (in order of increasing distance from Saturn according to JPL mean orbital elements):^[3]

Name	Diameter (km)	Period (days)	Subgroup
Phoebe	213	–550.30	Phoebe
S/2006 S 20	5	–567.27	Phoebe?[4][5][lower-alpha 1]
S/2006 S 9	3	–647.89	Phoebe?[6][lower-alpha 1]
Skathi	9	–728.10
S/2007 S 5	4	–746.88
S/2007 S 7	4	–754.29
S/2007 S 2	5	–754.90
S/2004 S 37	4	–754.48
S/2004 S 47	4	–762.49
S/2004 S 40	4	–764.60
S/2019 S 2	3	–799.82
S/2019 S 3	4	–837.74
S/2020 S 7	3	–861.70
Skoll	6	–878.44
S/2020 S 2	3	–897.60
S/2019 S 4	3	–904.26
S/2004 S 41	4	–914.61
S/2004 S 42	4	–925.91
Hyrrokkin	9	–931.89
Greip	6	–936.98
S/2004 S 13	4	–942.57
S/2007 S 6	3	–949.50
Mundilfari	8	–952.95
S/2006 S 1	5	–964.14
S/2004 S 43	4	–980.08
S/2006 S 10	3	–983.14
S/2019 S 5	3	–990.38
Gridr	5	–1004.75
Bergelmir	6	–1005.58
Jarnsaxa	5	–1006.92
Narvi	8	–1003.84
Suttungr	8	–1016.71
S/2004 S 44	5	–1026.16
S/2007 S 3	5	–1026.35
S/2004 S 45	4	–1038.70
Hati	6	–1040.29
S/2004 S 17	4	–1040.86
S/2006 S 11	3	–1042.28
S/2004 S 12	4	–1048.57
Eggther	6	–1052.33
S/2006 S 13	4	–1060.63
S/2007 S 9	4	–1078.07
S/2019 S 7	4	–1080.29
S/2019 S 8	4	–1088.68
Farbauti	5	–1087.29
Thrymr	9	–1091.84
Bestla	8	–1087.46
S/2019 S 9	4	–1093.11
S/2004 S 46	3	–1107.58
Angrboda	4	–1114.05
S/2019 S 11	4	–1115.00
Aegir	5	–1119.33
S/2019 S 10	3	–1123.04
Beli	4	–1121.76
S/2019 S 12	4	–1138.85
Gerd	4	–1142.97
S/2019 S 13	3	–1144.92
S/2006 S 14	3	–1152.68
Gunnlod	5	–1157.98
S/2019 S 15	3	–1161.54
S/2020 S 6	3	–1168.86
S/2004 S 7	5	–1173.93
S/2006 S 3	5	–1174.76
S/2005 S 5	3	–1177.82
Skrymir	5	–1185.15
S/2006 S 16	3	–1207.52
S/2006 S 15	4	–1213.96
S/2004 S 28	5	–1220.68
S/2020 S 8	3	–1228.12
Alvaldi	5	–1232.19
Kari	8	–1231.01
S/2004 S 48	4	–1242.40
Geirrod	4	–1251.14
Fenrir	4	–1260.25
S/2004 S 50	3	–1260.44
S/2006 S 17	4	–1264.58
S/2004 S 49	4	–1264.25
S/2019 S 17	4	–1291.39
Surtur	5	–1296.49
S/2006 S 18	4	–1298.40
Loge	6	–1311.83
Ymir	22	–1315.16
S/2019 S 19	3	–1318.05
S/2019 S 18	3	–1327.06
S/2004 S 21	4	–1325.43
S/2004 S 39	4	–1336.17
S/2019 S 16	3	–1341.17
S/2004 S 53	4	–1342.44
S/2004 S 36	4	–1352.93
Thiazzi	4	–1366.68
S/2019 S 20	3	–1375.45
S/2006 S 19	4	–1389.33
S/2004 S 34	4	–1420.77
Fornjot	6	–1494.03
S/2004 S 51	4	–1519.43
S/2020 S 10	3	–1527.22
S/2020 S 9	4	–1534.97
S/2004 S 26	5	–1603.95
S/2019 S 21	4	–1636.32
S/2004 S 52	3	–1633.98

Notes

1. May be a fragment of Phoebe, since it orbits at close proximity to Phoebe and could potentially be a part of the Phoebe subgroup.

See also

• List of natural satellites

References

1. NASA (October 7, 2019). "Saturn surpasses Jupiter after the discovery of 20 new moons—and you can help name them". phys.org.
2. "Names Approved for 10 Small Satellites of Saturn". usgs.gov. USGS. 24 August 2022. Retrieved 30 August 2022.
3. "Planetary Satellite Mean Orbital Parameters". Jet Propulsion Laboratory. Retrieved 7 June 2023.
4. Sheppard, Scott S.; Gladman, Brett J.; Alexandersen, Mike A.; Trujillo, Chadwick A. (May 2023). "New Jupiter and Saturn Satellites Reveal New Moon Dynamical Families". Research Notes of the American Astronomical Society. 7 (5): 100. Bibcode:2023RNAAS...7..100S. doi:10.3847/2515-5172/acd766. 100.
5. "S/2006 S 20". Tilmann Denk. Retrieved 18 January 2024.
6. "S/2006 S 9". Tilmann Denk. Retrieved 6 January 2024.

External links

• S. Sheppard's classification of Saturn's irregular moons