To look up the phase of the moon for any (Common Era) date,
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The full moon.

At 21:00:00 UT Tuesday 12 November 2019
the moon was


Some factors that go into this equation:

Universal Time is 21.0166666666667 in decimal hours.
The Julian date was 2458800.49915101.
The sun’s ecliptic longitude was 230.218152305411 degrees.
Its mean anomaly was 308.9393703792 degrees.
The moon’s mean longitude on 00 January 1990 was 318.351648 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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