👉 Perigeum, also known as the first day of the month in the Julian calendar, is a lunar period during which a moon appears to be "perigee" (the furthest point away from Earth) and "epigeum" (the closest point). Perigeum occurs every 29.5 days or 30.4 days after the full moon. This means that in the Julian calendar, it is approximately one month long.

perigeum