A
lunar conjunction is the moment of the new moon, when the sun, moon and earth are approximately in a straight line in that order. The period of time between two lunar conjunctions is the synodic month, which is a basic unit in most lunar and lunisolar
calendars such as the
Hebrew calendar. The opposite moment, when the sun, earth and moon are in approximately in a straight line in that order, is a full moon or lunar opposition.
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