An ecclesiastical new moon is the first day of a schematic lunar month in a computus. Such months have a variable number of whole days, 29 or 30, whereas true synodic months can vary from about 29.27 to 29.83 days in length. Medieval authors equated the ecclesiastical new moon with a new crescent moon, but it is not a phase of the true moon. If its computus is accurate, it can be any day from the day of the astronomical new moon or dark moon to two days later. It itself is only a minor part of a computus—the critical day is thirteen days later, specifically, the fourteenth day of the schematic lunar month which occurs on or next after March 21. This fourteenth day was loosely called the Paschal full moon by medieval computists. Easter is the following Sunday. Computus (Latin for computation) is the calculation of the date of Easter in the Christian calendar. ... In Egyptian mythology, Month is an alternate spelling for Menthu. ... Traditionally, the lunar phase new moon begins with the first visible crescent of the Moon, after conjunction with the Sun. ... The dark moon is the time when the Moon is so close to the Sun in the sky that it cannot be seen even near sunset or sunrise. ... Easter is the most important religious holiday of the Christian liturgical year, observed in March, April, or May to celebrate the resurrection of Jesus from the dead after his death by crucifixion (see Good Friday), which Christians believe happened at about this time of year around AD 30-33. ...