Gridr (moon)

{{Short description|Moon of Saturn}}

{{Infobox planet

| name = Gridr

| alt_names = Saturn LIV
S/2004 S 20
S2423b

| named_after = Gríðr

| discovery_ref = Discovery Circumstances [http://ssd.jpl.nasa.gov/?sat_discovery from JPL]

| discoverer = Sheppard et al.

| discovered = 2019

| orbit_ref = [https://sites.google.com/carnegiescience.edu/sheppard/moons/saturnmoons S.S. Sheppard (2019), Moons of Saturn, Carnegie Science, on line]

| semimajor = {{val|19211000|u=km}}

| inclination = 163.1°

| eccentricity = 0.204

| period = −990.23 days

| satellite_of = Saturn

| group = Norse group

| magnitude = 25.0

| mean_diameter = 4 km

}}

Gridr (Saturn LIV), 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.{{cite web |title=MPEC 2019-T126 : S/2004 S 20 |url=https://minorplanetcenter.net/mpec/K19/K19TC6.html |website=minorplanetcenter.net |accessdate=7 October 2019}} It was given its permanent designation in June 2021.{{cite web|title=M.P.C. 132212|url=https://minorplanetcenter.net/iau/ECS/MPCArchive/2021/MPC_20210601.pdf#page=1628|website=Minor Planet Center|publisher=International Astronomical Union|date=1 June 2021|access-date=16 June 2021}} On 24 August 2022, it was officially named after Gríðr, a jötunn in Norse mythology.{{cite web |url=https://astrogeology.usgs.gov/news/nomenclature/names-approved-for-10-small-satellites-of-saturn |title=Names Approved for 10 Small Satellites of Saturn |author= |date=24 August 2022 |website=usgs.gov |publisher=USGS |access-date=30 August 2022}} 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).{{Cite book|last=Lindow|first=John|url=https://books.google.com/books?id=KlT7tv3eMSwC|title=Norse Mythology: A Guide to Gods, Heroes, Rituals, and Beliefs|date=2002|publisher=Oxford University Press|isbn=978-0-19-983969-8|author-link=John Lindow|page=149}}

Gridr is about 4 kilometres in diameter, and orbits Saturn at an average distance of 19.418 Gm in 1010.55 days, at an inclination of 163° to the ecliptic, in a retrograde direction and with an eccentricity of 0.197.