Perigean spring tide Perigean spring tide A proxigean spring tide (also known as a perigean spring tide) is a tide that occurs three or four times per year when the Moon's perigee (its closest point to Earth during its 29.5-day elliptical orbit) coincides with a spring tide (when the Earth, Sun and Moon are nearly aligned every two weeks). This tide usually adds only a couple of inches to normal spring tides. The Moon's orbit around Earth is elliptical, which causes the Moon to be closer to Earth and farther away at different times. The Moon and the Sun are aligned every two
Ecclesiastical full moon of America, the dates of the paschal full moons for the 19 years of the Gregorian Easter cycle are indicated by the placement of the Golden Number to the left of the date in March or April on which the paschal full moon falls in that year of the cycle. The same practice is followed in some editions of the Book of Common Prayer of the Church of England. Notionally, the "paschal full moon" refers to the ecclesiastical full moon of the northern spring used in the determination of the date of Easter. The name "paschal" is derived from "Pascha",