if the moon is full and round
then the sun is underground

if the moon is hardly there
then the sun is somewhere near

if the moon looks like a D
a donut it is soon to be
 if its round the other way
then its Ceen to fade away

okay - this  verse is worse than bad and will be rewritten
but if the moon looks like a D it is waxing and if it looks like a C , it is waning

the diagram below shows why

sources and info

Moon Photos

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