Across North America, on July 31, at 11:12 p.m. Eastern, a “black moon” will be visible. Like a “blood moon” and a “blue moon,” a “black moon” is not actually an astronomical term in the strictest sense, it’s not even a particularly widely known folklore thing.
According to The Old Farmers Almanac, a black moon occurs if…
- There is a new moon twice in the same month —this is the definition of black moon that’s used most often.
- There are no new Moons in a month. This could only happen in February, and thus is kind of rare, meaning once every 5 to 10 years.
- The phrase might also simply refer to every new moon, since we’re then seeing the moon’s dark or black side.
- The phrase is also sometimes applied to mean the third new moon when there are four in a season, which is actually one of the definitions of a blue moon, when the same thing happens to a full moon.
So, as you can see, there’s a number of different interpretations of a “black moon,” which is why you might not see that July 31 black moon listed on every astronomy calendar.
There is no astronomical significance to a black moon. Nothing happens, except the usual new moon absence of any moon in the sky, plus the stronger so-called “spring” tides we get for a few days around every full Moon and new Moon.
If you’re willing to use any of the definitions above, you’ll get a black moon at least once a year, and sometimes twice. However, if we go by the standard “two new moons in one month” definition, black moons become slightly more rare, occurring about every 32 months (two to three years).
However, in some aspects of paganism, particularly amongst Wiccans, the black moon is considered to be a special time when any rituals, spells, or other workings are considered to be more powerful and effective. Others believe rituals or workings should not be conducted at these times.