= Synodic month
{title2=$P_{\mathrm{syn}}$}
= Lunation
{synonym}
A <synodic month> is the <synodic period> of the <Moon> relative to the <Sun>, about $29.53059$ days on average. A <lunation> is commonly measured from one new Moon to the next. Actual <lunations> vary, so the constant-speed relation derived in <lunar phase> is useful for understanding the mean cycle rather than predicting exact dates. https://eclipse.gsfc.nasa.gov/SEhelp/moonorbit.html[Fred Espenak, NASA: the synodic month and lunation]{ref}.
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