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(Engels)
The moon phase is caused by sun rays reflecting off the
moon'ssurface while it moves around the earth. The sun illuminates half of
the moon at any time while the moon orbits
around the earth. The variation in the
angle made by the earth- moon line with respect to the
earth-sun line causes changing phase of the moon. The
moon completes one revolution around the earth in 27.322 days with
respect to the background stars.This is called the SIDERIALperiod of the
moon. During this same time the earth moves about 27 degrees
along its orbit around the sun. As a result, the moon takes about
two extra days to complete the cycle with respect to the sunearth line.
This longer cycle of the moon that takes about 29.57days is called
SYNDONIC period of the moon. The longer cycle isconsidered as Lunar month.
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