Editing Fortnight (section)

==Astronomy and tides==
{{further|Eclipse cycle}}
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In [[astronomy]], a ''lunar fortnight'' is half a [[Lunar month#Synodic month|lunar synodic month]], which is equivalent to the [[arithmetic mean|mean]] period between a full moon and a new moon (and vice versa). This is equal to 14.77 days.<ref name="totality">{{cite book |last=Littmann |first=Mark |author2=Fred Espenak |author3=Ken Willcox |title=Totality: Eclipses of the Sun |publisher=[[Oxford University Press]] |year=2008 |isbn=978-0-19-953209-4}}</ref><ref>{{cite web |url=http://scienceworld.wolfram.com/astronomy/SynodicMonth.html |title=Synodic Month definition |first=Eric W. |last=Weisstein}}</ref>
It gives rise to a lunar fortnightly [[tidal constituent]] (see: [[Long-period tides]]).