A "Black Moon" refers to the occurrence of a second new moon within a single calendar month. This phenomenon is relatively rare, happening approximately once every 29 months. Unlike a full moon, a new moon is when the moon is positioned between the Earth and the sun, making it invisible from our perspective. The term "Black Moon" can also refer to the absence of a full moon in February, which occurs in some years. Both definitions highlight the moon's phases and their impact on our calendar, showcasing the moon's influence on timekeeping and cultural events related to lunar cycles.