Full Moon Sunday in April

Traditionally, the April full moon is known as the "Pink Moon,"supposedly because the grass pink or wild ground phlox is one of the earliest widespread flowers of the spring. Other monikers were the Full Sprouting Grass Moon, the Egg Moon, and – among coastal tribes – the Full Fish Moon, when the shad come upstream to spawn. ['Supermoon' Photos from Around the World]

Easter's full moon twist

The first full moon of spring, however, is usually designated as the Paschal Full Moon or the Paschal Term. Traditionally, Easter is observed on the Sunday after the Paschal Full Moon. So if the Paschal Moon occurs on a Sunday, Easter is the following Sunday.

Following these celestial rules, we find that Easter can fall as early as March 22 and as late as April 25.

Pope Gregory XIII decreed this in 1582 as part of the Gregorian calendar. So according to the current ecclesiastical rules Easter in 2011 is to be celebrated nearly as late as it can come, on April 24.