▁formula ▁and ▁its ▁parameters . ▁ ▁The ▁age ▁and ▁apparent ▁size ▁of ▁the ▁full ▁moon ▁vary ▁in ▁a ▁cycle ▁of ▁just ▁under ▁ 1 4 ▁syn od ic ▁months , ▁which ▁has ▁been ▁referred ▁to ▁as ▁a ▁full ▁moon ▁cycle . ▁ ▁L un ar ▁e cli ps es ▁ ▁When ▁the ▁Moon ▁moves ▁into ▁Earth ' s ▁shadow , ▁a ▁lun ar ▁eclipse ▁occurs , ▁during ▁which ▁all ▁or ▁part ▁of ▁the ▁Moon ' s ▁face ▁may ▁appear ▁re dd ish ▁due ▁to ▁the ▁Ray le igh ▁scatter ing ▁of ▁blue ▁w avel ength s ▁and ▁the ▁ref raction ▁of ▁sun light ▁through ▁Earth ' s ▁atmosphere . ▁L un ar ▁e cli ps es ▁happen ▁only ▁during ▁a ▁full ▁moon ▁and ▁around ▁points ▁on ▁its ▁orbit ▁where ▁the ▁satellite ▁may ▁pass ▁through ▁the ▁planet ' s ▁shadow . ▁A ▁lun ar ▁eclipse ▁does ▁not ▁occur ▁every ▁month ▁because ▁the ▁Moon ' s ▁orbit ▁is ▁incl ined ▁ 5 . 1 4 ° ▁with ▁respect ▁to ▁the ▁e cli ptic ▁plane ▁of ▁Earth ; ▁thus , ▁the ▁Moon ▁usually ▁passes ▁north ▁or ▁south ▁of ▁Earth ' s ▁shadow , ▁which ▁is ▁mostly ▁restricted ▁to ▁this ▁plane ▁of ▁reference . ▁L un ar ▁e cli ps es ▁happen ▁only ▁when ▁the ▁full ▁moon ▁occurs ▁around ▁either ▁node ▁of ▁its ▁orbit ▁( asc ending ▁or ▁desc ending ). ▁Therefore , ▁a ▁lun ar ▁eclipse ▁occurs ▁about ▁every ▁six ▁months , ▁and ▁often ▁two ▁weeks ▁before ▁or ▁after ▁a ▁solar ▁eclipse , ▁which ▁occurs ▁during