Norse group

The Norse group is a large group of retrograde irregular satellites of Saturn. Their semi-major axes range between 12 and 24 Gm, their inclinations between 136° and 175° and their eccentricities between 0.13 and 0.77. Unlike for 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 homogenous 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 mi) 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]

• Phoebe (Phoebe subgroup)
• S/2006 S 20 (Phoebe subgroup)[4]
• S/2006 S 9
• Skathi
• S/2007 S 5
• S/2007 S 7
• S/2007 S 2
• S/2004 S 37
• S/2004 S 47
• S/2004 S 40
• S/2019 S 2
• S/2019 S 3
• S/2020 S 7
• Skoll
• S/2020 S 2
• S/2019 S 4
• S/2004 S 41
• S/2004 S 42
• Hyrrokkin
• Greip
• S/2004 S 13
• S/2007 S 6
• Mundilfari
• S/2006 S 1
• S/2004 S 43
• S/2006 S 10
• S/2019 S 5
• Gridr
• Bergelmir
• Jarnsaxa
• Narvi
• Suttungr
• S/2007 S 3
• S/2004 S 44
• S/2004 S 45
• Hati
• S/2004 S 17
• S/2006 S 11
• S/2004 S 12
• Eggther
• S/2006 S 13
• S/2007 S 9
• S/2019 S 7
• S/2019 S 8
• Farbauti
• Thrymr
• Bestla
• S/2019 S 9
• S/2004 S 46
• Angrboda
• S/2019 S 11
• Aegir
• Beli
• S/2019 S 10
• S/2019 S 12
• Gerd
• S/2019 S 13
• S/2006 S 14
• Gunnlod
• S/2019 S 15
• S/2020 S 6
• S/2004 S 7
• S/2006 S 3
• S/2005 S 5
• Skrymir
• S/2006 S 16
• S/2006 S 15
• S/2004 S 28
• S/2020 S 8
• Alvaldi
• Kari
• S/2004 S 48
• Geirrod
• Fenrir
• S/2004 S 50
• S/2006 S 17
• S/2004 S 49
• S/2019 S 17
• Surtur
• S/2006 S 18
• Loge
• Ymir
• S/2019 S 19
• S/2004 S 21
• S/2019 S 18
• S/2004 S 39
• S/2019 S 16
• S/2004 S 53
• S/2004 S 36
• Thiazzi
• S/2019 S 20
• S/2006 S 19
• Saturn LXIV
• Fornjot
• S/2004 S 51
• S/2020 S 10
• S/2020 S 9
• Saturn LVIII
• S/2019 S 21
• S/2004 S 52