The lunar cycle of a new moon is approximately 29.5 days, which means, on a rare occasion, it can happen twice in single month. Hence, the black moon is the extra new moon in a cycle.

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 ...

The black moon, which is also sometimes called an invisible moon, will rise on Dec. 30. The moon will gradually become more visible as it heads to the first-quarter stage by Jan. 6.

And when there’s no new moon in February — about once every 20 years — it results in black moons in January and March. But, generally, a black moon is the extra new moon in a cycle.

In metro Phoenix, the black moon on Monday, Dec. 30, can be observed by finding a clear spot with minimal light pollution, though the moon itself will be invisible due to its alignment.