To look up the phase of the moon for any (Common Era) date,
just fill out the form below, then hit “Find Phase.”

The waxing moon.

At 17:15:49 UT Monday 25 January 2021
the moon’s phase is

WAXING GIBBOUS (90.02% full)


Some factors that go into this equation:

Universal Time is 17.2802777777778 in decimal hours.
The Julian date is 2459240.40021097.
The sun’s ecliptic longitude is 305.971181009769 degrees.
Its mean anomaly is 22.4707587797 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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