Editing Natural satellite (section)

=== Definition of a moon ===
[[File:Moon, Earth size comparison.jpg|thumb|Size comparison of [[Earth]] and the [[Moon]]]]

There is no established lower limit on what is considered a "moon". Every natural celestial body with an identified orbit around a planet of the [[Solar System]], some as small as a kilometer across, has been considered a moon, though objects a tenth that size within Saturn's rings, which have not been directly observed, have been called ''[[moonlet]]s''. Small [[Minor-planet moon|asteroid moons]] (natural satellites of asteroids), such as [[Dactyl (moon)|Dactyl]], have also been called moonlets.<ref name="Marchis05">{{cite journal|author=F. Marchis|title=Discovery of the triple asteroidal system 87 Sylvia|journal=Nature|volume=436|pages=822–824|date=2005|bibcode=2005Natur.436..822M|doi=10.1038/nature04018|pmid=16094362|issue=7052|name-list-style=vanc|display-authors=1|last2=Descamps|first2=Pascal|last3=Hestroffer|first3=Daniel|last4=Berthier|first4=Jérome|s2cid=4412813|url=https://escholarship.org/uc/item/7nb376hk}}</ref>

The upper limit is also vague. Two orbiting bodies are sometimes described as a [[double planet]] rather than a primary and satellite. [[Asteroid]]s such as [[90 Antiope]] are considered double asteroids, but they have not forced a clear definition of what constitutes a moon. Some authors consider the Pluto–Charon system to be a double (dwarf) planet. The most common{{citation needed|date=January 2012}} dividing line on what is considered a moon rests upon whether the [[barycentre]] is below the surface of the larger body, though this is somewhat arbitrary because it depends on distance as well as relative mass.