Easter moonrise

The moon rises over Ahu Akivi on Easter Island.

Easter 2008 falls on March 23. According to western Christianity's rules for calculating the date of Easter, this movable feast will not arrive as early in the calendar for another 152 years (2160). Easter will not fall on the earliest possible date of March 22 until 2285. Some bristlecone pines alive today, God willing, will see that date. That is a better bet, environmental degradation and climate change notwithstanding, than the prospects facing any human alive today.

Under the western definition of the Paschal full moon, Easter always takes place under a moon that is no dimmer than the third quarter. This year's calendar places a nearly full moon on top of Easter. In the southern hemisphere, that full moon coincides with the autumnal rather than the vernal equinox. Whether it is observed from Ahu Akivi on Easter Island (a configuration of seven moai — monolithic ceremonial sculptures made of volcanic ash — aligned according to sunset at the equinox), or or from any other point south of the equator, the Easter moon is the astronomical equivalent of what we northerners call the harvest moon.

Happy Easter.