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The waning moon.

At 20:41:22 UT Sunday 19 February 2017
the waning moon’s phase is

40.22% full

Time Zone:   

Some factors that go into this equation:

Universal Time is 20.7061111111111 in decimal hours.
The Julian date is 2457803.90217588.
The sun’s ecliptic longitude is 331.39598392671 degrees.
Its mean anomaly is 47.22184932389 degrees.
The moon’s true longitude is 252.678579745649 degrees.

These calculations incorporate the switch to the English New Style (N.S.)—i.e., Gregorian— calendar after Wednesday, 02 September 1752; the next day became Thursday, 14 September, skipping eleven days. (Please also note that, while fairly accurate, these calculations remain a bit buggy.)

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