Editing Orbital resonance (section)

=== Plutino resonances ===
The dwarf planet [[Pluto]] is following an orbit trapped in a web of resonances with [[Neptune]]. The resonances include:
*A mean-motion resonance of 2:3
*The resonance of the [[perihelion]] ([[libration]] around 90°), keeping the perihelion above the [[ecliptic]]
*The resonance of the longitude of the perihelion in relation to that of Neptune
One consequence of these resonances is that a separation of at least 30 AU is maintained when Pluto crosses Neptune's orbit. The minimum separation between the two bodies overall is 17 AU, while the minimum separation between Pluto and [[Uranus]] is just 11 AU<ref>{{cite web |last=Malhotra |first=R. |author-link=Renu Malhotra |date=1997 |title=Pluto's Orbit |url=http://www.nineplanets.org/plutodyn.html |access-date=26 March 2007}}</ref> (see [[Pluto#Orbit|Pluto's orbit]] for detailed explanation and graphs).

The next largest body in a similar 2:3 resonance with Neptune, called a ''[[plutino]]'', is the probable dwarf planet [[90482 Orcus|Orcus]]. Orcus has an orbit similar in inclination and eccentricity to Pluto's. However, the two are constrained by their mutual resonance with Neptune to always be in opposite phases of their orbits; Orcus is thus sometimes described as the "anti-Pluto".<ref name=MBP>{{cite web |last=Brown |first=M. E. |author-link=Michael E. Brown |date=23 March 2009 |title=S/2005 (90482) 1 needs your help |work=[[Mike Brown's Planets]] |url=http://www.mikebrownsplanets.com/2009/03/s1-90482-2005-needs-your-help.html |access-date=25 March 2009}}</ref>

[[File:Naiad-Thalassa 73-69 orbital resonance.jpg|thumb|300px|Depiction of the resonance between Neptune's moons [[Naiad (moon)|Naiad]] (whose orbital motion is shown in red) and [[Thalassa (moon)|Thalassa]], in a view that co-rotates with the latter]]