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

The waning moon.

At 20:26:00 UT Tuesday 21 September 2021
the moon’s phase was

WANING GIBBOUS (99.23% full)

Some factors that go into this equation:

Universal Time is 20.45 in decimal hours.
The Julian date was 2459479.49231491.
The sun’s ecliptic longitude was 179.064579774046 degrees.
Its mean anomaly was 258.1706531364 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.)

 Send comments to

© 1997–2021 by 3IP.