Lunar Phases Interactive (124.0K)
These phases can be matched to the appearance and rising a setting times for the Moon in this cycle, as we shall explore with this interactive and this question.
As the moon takes about 30 days to circle the sky, each day it moves about 12 degrees on average. Let's see how this relates to civil time keeping.
The phase, or synodic month, is 29.5 earth days long. Let's see how this relates to one of the rarer calendar cycles, since our modern months are only loosely based on the original phase cycles.
The cycle of lunar phases gave us our month, and a predictable set of alignments that still today set the Muslim, Chinese, and Jewish calendars, as well as the date of Easter Sunday for Christians. Of these, only the Muslim one makes no adjustments for the solar year, however.
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