about the moon's phases

Traditionally, there are eight phases of the moon. They are: The New Moon, Waxing Crescent (also called a "Evening Crescent"), First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter (or "Last Quarter"), Waning Crescent (also called an "Morning Crescent") and back to the New Moon where the lunar cycle begins again. The First Quarter and Last Quarter moons are sometimes descriptively called "Half Moons", but the correct term is "Quarter Moon" because they represent the points at 25% and 75% of the full lunar cycle.

 

During a Full Moon and a New Moon the Earth's tides are highest (often called a "Spring Tide", although the effect happens at any time of year). During each of the moon's Quarter phases, or "Neap Tides" the Earth's tides are at their lowest.

 

To calculate the phase of the moon for any date with extreme precision, one must account for differences between world time-zones. For simplicity's sake the above Moon Phase Search makes moon phase calculations based upon 12pm Universal Time.