Solar System: Difference between revisions

Revision as of 22:32, 9 April 2007

Revision as of 22:37, 9 April 2007

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[[Image:Pluto_system_2006.jpg|right|thumb|180px|Pluto, and its three known moons]]

; Pluto and Charon

: [[Pluto]] (39 AU average), a dwarf planet, is the one of the largest known objectobjects in the Kuiper belt. When discovered in 1930 it was considered to be the ninth planet; this changed in 2006 with the adoption of a formal [[definition of planet]]. Pluto has a relatively eccentric orbit inclined 17 degrees to the ecliptic plane and ranging from 29.7 AU from the Sun at perihelion (within the orbit of Neptune) to 49.5 AU at aphelion.

: It is unclear whether [[Charon (moon)|Charon]], Pluto's largest moon, will continue to be classified as such or as a dwarf planet itself. Both Pluto and Charon orbit a [[barycenter]] of gravity above their surfaces, making Pluto-Charon a [[binary system]]. Two much smaller moons, [[Nix (moon)|Nix]] and [[Hydra (moon)|Hydra]], orbit Pluto and Charon.

: Pluto lies in the resonant belt, having a 3:2 resonance with Neptune (it orbits twice round the Sun for every three Neptunian orbits). Kuiper belt objects which share this orbit are called [[Plutino]]s.<ref name="Fajans_et_al_2001">{{cite science | last = Fajans | first = J. | coauthors = L. Frièdland | month = October | year = 2001 | title = Autoresonant (nonstationary) excitation of pendulums, Plutinos, plasmas, and other nonlinear oscillators | journal = American Journal of Physics | volume = 69 | issue = 10 | pages = 1096-1102 | doi = 10.1119/1.1389278 | url = http://scitation.aip.org/journals/doc/AJPIAS-ft/vol_69/iss_10/1096_1.html | accessdate = 2006-12-26| abstract = http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000069000010001096000001&idtype=cvips&gifs=yes}} </ref>