Editing Binary system (section)

== Binary companion (minor planets) ==
[[File:Pluto-Charon_system-new.gif|thumb|right|The dwarf planet [[Pluto]] and its moon [[Charon (moon)|Charon]] are often described as a binary system in the [[Solar System]], which orbit the [[Sun]].]]
{{main|Binary asteroid}}

When binary minor planets are similar in size, they may be called "[[Binary asteroid|binary companions]]" instead of referring to the smaller body as a satellite.<ref name="IAU-list">{{cite web |date=2009-09-17 |title=Satellites and Companions of Minor Planets |publisher=IAU / [[Minor Planet Center]] |url=http://www.cbat.eps.harvard.edu/minorsats.html |access-date=2011-01-08 |url-status=dead |archive-url=https://web.archive.org/web/20110121153650/http://www.cbat.eps.harvard.edu/minorsats.html |archive-date=2011-01-21 }}</ref> Good examples of true binary companions are the [[90 Antiope]] and the [[79360 Sila–Nunam]] systems. [[Pluto]] and its largest moon [[Charon (moon)|Charon]] are sometimes described as a binary system because the [[barycenter]] (center of mass) of the two objects is not inside either of them, but Charon is small enough compared to Pluto that it is usually classified as a moon.<ref>{{cite web |url=http://news.discovery.com/space/can-we-call-pluto-and-charon-a-binary-planet-yet-140808.htm |title=Can We Call Pluto and Charon a 'Binary Planet' Yet? |author=Ian O'Neill |website=Discovery News |date=8 August 2014 |access-date=15 July 2015}}</ref> [[90482 Orcus|Orcus]] and its moon [[Vanth_(moon)|Vanth]] also orbit around a barycenter not inside either of them.
The Sun and Jupiter orbit a point outside of either, but are not considered a binary because they are different kinds of objects.