Pallene (moon)

Pallene (pronEng|pəˈliːni respell|pə|LEE|nee, or as Greek "Παλλήνη)" is a very small natural satellite of Saturn lying between the orbits of Mimas and Enceladus.

It was first seen during the Cassini-Huygens mission by the [http://ciclops.org/team/iss_team.php Cassini Imaging Team] [* [http://cfa-www.harvard.edu/iauc/08300/08389.html C.C. Porco, et al., IAUC 8389: "S/2004 S 1 and S/2004 S 2"] 2004 August 16 (discovery)] Porco, C. C.; "et al."; (2005); [http://www.sciencemag.org/cgi/content/short/307/5713/1226 "Cassini Imaging Science: Initial Results on Saturn's Rings and Small Satellites"] , Science, Vol. 307, No. 5713, pp. 1226-1236] in 2004, and given the temporary designation nowrap|S/2004 S 2. It was actually first seen on August 23, 1981 by "nowrap|Voyager 2" in a single photograph and named nowrap|S/1981 S 14 and its distance to Saturn was then estimated at 200,000 km. [ [http://cfa-www.harvard.edu/iauc/06100/06162.html IAUC 6162: "Possible Satellites of Saturn"] 1995 April 14] Since it was not visible in other images, its orbit could not be calculated at the time, but recent comparisons have identified it as matching Pallene's orbit. Pallene is also designated as nowrap|Saturn XXXIII.

Pallene is visibly affected by a perturbing mean longitude resonance with the much larger Enceladus, although this effect is not as large as the Mimas perturbations on Methone. The perturbations cause Pallene's osculating orbital elements to vary with an amplitude of about 4 km in semi-major axis, and 0.02° in longitude (corresponding to about 75 km). Eccentricity also changes on various timescales between 0.002 and 0.006, and inclination between about 0.178° and 0.184°.

The names Methone and Pallene were provisionally approved by the IAU Division III Working Group for Planetary System Nomenclature in 2005 [ [http://cfa-www.harvard.edu/iauc/08400/08471.html IAUC 8471: "Satellites of Saturn"] 2005 January 21 (naming the moon)] and were ratified at the IAU General Assembly in 2006. Pallene was one of the Alkyonides, the seven beautiful daughters of the Giant Alkyoneus.

The Pallene Ring, a faint dust ring, also discovered by the [http://ciclops.org Cassini Imaging Team] , [ [http://cfa-www.harvard.edu/iauc/08700/08759.html C.C. Porco, et al., IAUC 8759: "Rings of Saturn (R/2006 S 1, R/2006 S 2, R/2006 S 3, R/2006 S 4)"] (subscription-only) 2006 October 11] shares Pallene's orbit, as revealed by images taken in forward-scattered light by the Cassini spacecraft in 2006. [ [http://ciclops.org/view.php?id=2276 "Moonmade Rings"] ] The ring has a radial extent of about 2,500 km. Its source is particles blasted off Pallene's surface by meteoroid impacts, which then form a diffuse ring around its orbital path.Cassini-Huygens press release [http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=698 "NASA Finds Saturn's Moons May Be Creating New Rings"] , 11 October, 2006] [Early press releases of the discovery mentioned the first person to see the moon in Cassini images. This bit of trivia was blown out of proportion in the following months, with this individual being credited as the "discoverer" by some sources. Because the discovery was a large team effort, involving tens of people and hundreds of hours of distributed work, a conscious decision was made by the IAU to officially and correctly assign any credit to "the Cassini Imaging team" and to avoid unfairly singling out any one individual as the discoverer.]

References

External links

* [http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sat_Pallene Pallene Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]