December ends with a “black moon,” but those hoping to see the phenomenon will be out of luck.
This is because a black moon is the term for the second new moon that falls in a single calendar month, and new moons appear invisible to the naked eye from Earth. While new moons occur 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 over the next few days, reaching its first quarter phase on Jan. 6 and becoming a full moon on 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 August 23rd.
The term black moon can also be used when there are no new moons in a month, which can only happen in February due to its short duration. 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 each new moon, since in this phase, the illuminated side of the moon cannot be seen from Earth.
Most months have a full moon and a new moon because the lunar calendar largely aligns with a calendar year. But just as there can be two new moons in a single month, there can also be two full moons, and the second full moon in a single month is considered a blue moon. Just as the black moon can have more than one meaning, the blue moon also refers to the third full moon in a season with four full moons.
No monthly or seasonal blue moons in 2025, according to TimeAndDate.com. The next monthly blue moon will be May 31, 2026, and the next seasonal blue moon will fall on May 20, 2027, with dates that vary by time zone.