Editing Natural satellite (section)

== Tidal locking ==
{{main|Tidal locking}}

Most [[regular moon]]s (natural satellites following relatively close and prograde orbits with small orbital inclination and eccentricity) in the Solar System are tidally locked to their respective primaries, meaning that the same side of the natural satellite always faces its planet. This phenomenon comes about through a loss of energy due to tidal forces raised by the planet, slowing the rotation of the satellite until it is negligible.<ref name=Barnes_2010>{{cite book | title=Formation and Evolution of Exoplanets | editor1-first=Rory | editor1-last=Barnes | publisher=John Wiley & Sons | year=2010 | isbn=978-3527408962 | page=248 | url=https://books.google.com/books?id=-7KimFtJnIAC&pg=PA248 }}</ref> Exceptions are known; one such exception is [[Saturn]]'s natural satellite [[Hyperion (moon)|Hyperion]], which rotates chaotically because of the gravitational influence of [[Titan (moon)|Titan]]. Pluto's four, circumbinary small moons also rotate chaotically due to Charon's influence.<ref name="NASA2015"/>

In contrast, the outer natural satellites of the giant planets (irregular satellites) are too far away to have become locked. For example, Jupiter's [[Himalia (moon)|Himalia]], Saturn's [[Phoebe (moon)|Phoebe]], and Neptune's [[Nereid (moon)|Nereid]] have rotation periods in the range of ten hours, whereas their orbital periods are hundreds of days.