December is coming to an end with a “black moon” on Monday night, Dec. 30, but those hoping to see the phenomenon will be out of luck.
That’s because a black moon is the term for the second new moon to fall in a single calendar month, and new moons appear invisible to the naked eye from Earth. While new moons happen throughout the year, two new moons only fall in a single calendar month about once every 29 months, according to the Old Farmer’s Almanac.
The moon will gradually become more visible in the coming days, reaching its first-quarter stage by Jan. 6 and becoming a full moon by Jan. 13, according to NASA.
Those hoping to catch another black moon won’t have to wait too long, as there are actually several types of black moons, according to the Old Farmer’s Almanac. Some people use the term to refer to the third new moon in a season that has four new moons. This type of black moon is rarer than the more common definition, occurring once every 33 months. The next black moon under this definition will be on Aug. 23.
The term black moon can also be used when there are no new moons in a month, which can only happen in February because of its short length. This only happens every 19 years or so, with the next one in 2033, according to the Old Farmer’s Almanac.
Some even use the term black moon to refer to every new moon, since at that phase, the illuminated face of the moon can’t be seen from Earth.
Most months have one full moon and one new moon because the lunar calendar largely lines up with a calendar year. But just as it’s possible for there to be two new moons in a single month, there can also be two full moons, with the second full moon in a single month considered a blue moon. Similar to how black moon can have more than one meaning, blue moon also refers to the third full moon in a season with four full moons.
There are no monthly or seasonal blue moons in 2025, according to TimeAndDate.com. The next monthly blue moon is on May 31, 2026 and the next seasonal blue moon will fall on May 20, 2027, with dates varying depending on time zone.
