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because there is a new moon in new moon
1st quarter moon . . . 7.38 days after New Moon
Full moon . . . 14.77 days after New Moon
3rd quarter moon . . . 22.15 days after New Moon
New Moon . . . 29.53 days after the previous New Moon.
There new moon!
The New Moon always occurs very close to the moon's "new moon" phase.
There is no "old moon". The opposite of a new moon is a full moon.