Greip (moon)

Greip
Greip imaged by the Cassini spacecraft in September 2015
Discovery
Discovered byScott S. Sheppard
David C. Jewitt
Jan T. Kleyna
Brian G. Marsden
Discovery date2006
Designations
Designation
Saturn LI
Named after
Greipa
S/2006 S 4
Orbital characteristics[1]
18206000 km
Eccentricity0.326
−921.2 days
Inclination179.8°
Satellite ofSaturn
GroupNorse group
Physical characteristics[2][3]
5+50%
−30%
 km
12.75±0.35? h
Albedo0.06 (assumed)
24.4
15.4

Greip /ˈɡrp/ or Saturn LI is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 26 June 2006, from observations taken between 5 January and 1 May 2006. Greip is about 5 kilometres in diameter, and orbits Saturn at an average distance of 18,066 Mm in 906.556 days, at an inclination of 172.7° to the ecliptic (159.2° to Saturn's equator), in a retrograde direction and with an eccentricity of 0.3735, and is presumably at high risk of eventually colliding with Phoebe.[3] It is unknown whether Greip is more similar to Suttungr or Hyrrokkin in color.[3] Its rotation period is most likely 12.75±0.35 hours with two minima in the light curve,[2] but a longer period of 19 hours cannot be ruled out due to the short observation time by Cassini–Huygens.[3]

It is named after Greip, a giantess in Norse mythology.

  1. ^ S.S. Sheppard (2019), Moons of Saturn, Carnegie Science, on line
  2. ^ a b Denk, T.; Mottola, S. (2019). Cassini Observations of Saturn's Irregular Moons (PDF). 50th Lunar and Planetary Science Conference. Lunar and Planetary Institute.
  3. ^ a b c d Denk, Tilmann; Mottola, Stefano; Tosi, Frederico; Bottke, William F.; Hamilton, Douglas P. (2018). "The Irregular Satellites of Saturn" (PDF). In Schenk, P.M.; Clark, R.N.; Howett, C.J.A.; Verbiscer, A.J.; Waite, J.H. (eds.). Enceladus and the Icy Moons of Saturn. Space Science Series. Vol. 322. Tucson, AZ: The University of Arizona Press. pp. 409–434. Bibcode:2018eims.book..409D. doi:10.2458/azu_uapress_9780816537075-ch020. ISBN 9780816537075.