First, I must say, that the concept of a Black Moon is very new to me. So much so, that I have only heard of its existence during the last few years. However, when researching about a Black Moon, I have found that the concept within the astronomers association is also relatively new, so don′t feel bad if you have never heard of a Black Moon either.

Since the phrase Black Moon is not an official Astronomical term, but is a colloquial expression for a supposed celestial event, I will entertain those definitions that I have been seeing within the internet channels. So far, I have found three definitions that have popped up in the internet buzz.

A Black Moon is the second New Moon in a Calendar Month, which is the most common.

This definition for a Black Moon occurs approximately once every 29 months.

(Source: https://www.space.com/what-is-black-moon-when-is-next-one)

The Third New Moon when four New Moons occur in one three month season.

This definition for a Black Moon occurs approximately once every 33 months.

(Source: https://www.space.com/what-is-black-moon-when-is-next-one)

A Black Moon is when there is no New Moon in February.

Due to the fact that the month of February is shorter than the lunar cycle (about 29.5 days),

thus, the month of February can span an entire calendar month without a new moon.

February, always shorter than the lunar cycle, even in a leap year,

can, at times, have no new moon, but also at times not have a full moon.

One source, says, when the absence or either a new or full moon in February happens,

it can be referred to as a Black Moon for that month.

(Source: https://en.wikipedia.org/wiki/Black_moon)

A Black Moon most universally defines the second New Moon in a single calendar month. Because lunar cycles are slightly shorter than our Gregorian calendar months, two New Moons can occasionally fall into the same month. It serves as the New Moon equivalent to a Blue Moon.

A Black Moon correlates to a new moon just as a Blue Moon correlates to a full moon

For a deeper explanation of the science of the the Lunar Cycle, also referred to a Lunation, please go to Lunation: Lunar Cycle