What is a "Black Moon"?

1 May 2014

THE SHORT ANSWER (TSA)

            The “black moon” refers most directly to the new moon. A new moon is dark with no part of lunar disk reflecting any of the sun’s light. The new moon is, in a way, the opposite of the full moon.   Just as the term “blue moon” refers to the number of full moon’s in a calendar month or calendar season, so, the term “black moon” refers to the number of new moon’s in a calendar month or calendar season.

First, a black moon is the second new moon in the same calendar month. (This can never happen in the month of February.)

Second, if there are four new moons in a particular season, spring, summer, winter, or fall, the third new moon of the four is called a “black moon.” (Only occasionally does a calendar season have four, instead of three, new moons.)

Third, a black moon is a new moon in the month of February when there is no full moon in that same month. (This can only happen in the month of February.)
Fourth, a black moon is a new moon that falls late-January when there is no new moon in the next month (February).

What’s so special about February?

The moon takes a little over 29 days to circle the earth. So, a lunar cycle, (new moon to the next new moon or full moon to the next full moon), always takes a little over 29 days. Every calendar month is longer than a full lunar cycle — except February.    And February is the only month that is always shorter than a full lunar cycle.   So, if a new moon (or full moon) falls on January 31st, the next new moon (or full moon) won’t happen until March.   February will be skipped completely.

Result: Every month must have, at least, one new and one full moon – except February. Also, every month can occasionally have two new moons or two full moons – except February.


I don’t know that the “black moon” is associated with anything other than the new moon. Several sources have suggested that the “black moon” has, sometimes, been given some special historical meaning or significance. But, I believe these comments are the result of confusing the “black moon” with “the dark of the moon.”  “The dark of the moon” is a period of 3 days before the new moon which, in folklore, was believed to be an especially unfavorable time to plant crops as well as begin or advance enterprises of any kind.

M Grossmann of Hazelwood, Missouri
(& Belleville, Illinois)
About the Author
1 May 2014