It is not a term used in astronomy and there is no single accepted definition of it.
[2] One use of the term is for the occurrence of a second new moon in a calendar month.
[2][4] There is no dependency on time zones in this definition as the seasons are tied to the winter solstice.
Calculated in UTC, instances of a month without full moon between 1990 and 2040 are:[10][11] Another use of the term is for the absence of the new moon in a calendar month.
Calculated in UTC, instances of a month without new moon between 1990 and 2040 are:[10][11] In some aspects of paganism, particularly amongst Wiccans, the black moon is considered to be a special time when any rituals, spells, or other workings are considered to be more powerful and effective.