What to know about tonight’s “black moon”

December is coming to an end with a “black moon”, 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 that occurs in a single calendar month, and new moons appear to be invisible to the naked eye from Earth. While new moons occur throughout the year, two new moons only occur in a single calendar month approximately once every 29 months, according to Old farmer’s almanac.

The moon will gradually become more visible in the coming days, reaching its first quarter stage on Jan. 6 and becoming full on Jan. 13, according to NASA.

Those hoping to catch another black moon don’t have to wait too long, as there are actually several types of black moons, according to 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 for a month, which can only happen in February due to its short length. This only happens every 19 years or so, with the next in 2033, according to the Old Farmer’s Almanac.

Some even use the term black moon to refer to each new moon, since the illuminated face of the moon during that phase cannot be seen from Earth.

Most months have one full moon and one new moon because the lunar calendar roughly matches a calendar year. But just as it is 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 being 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 of four full moons.

There are no monthly or seasonal blue moons in 2025, according to TimeAndDate.com. The next monthly blue moon is May 31, 2026, and the next seasonal blue moon occurs on May 20, 2027, with dates varying by time zone.