What does "wax" mean here? Does it mean the moon looks shinier as if it was polished by wax?
Good guess! A "waxing moon" is a moon that is growing brighter, to eventually become a full moon. Some people like to remember this by thinking of "waxing" as "maxing" (i.e. growing bigger). Thus, a "waning moon" is the opposite and refers to the period after a full moon, when a moon grows dimmer and is closer to the shape of a crescent. Ex: The moon is waxing, so it looks like we'll be able to see a full moon soon. Ex: A waning moon means that the illuminated area is decreasing in size.
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