Don't be surprised if the Easter Bunny plays a few pranks in 2018—the Christian holiday , this year. Ash Wednesday is pulling double-duty too, sharing a calendar date with this February. It's the first time this odd occurrence has appeared on the calendar since 1945.
The coincidence has left many people wondering why falls on a different date each year, anyway. Most Christians know Ash Wednesday's date depends on Easter's, but wouldn't it be much simpler (and easier to remember) if Jesus Christ's resurrection were celebrated on a set day, the way holidays like Christmas and Valentine's Day are observed? Here's a look at why that's not the case.
For Catholics, Ash Wednesday signals the period of 40 days before Easter, called Lent, when observants typically "give up" some earthly pleasure (wine, chocolate) as a form of penance. The holiday stems from the Old Testament book of ," according to priest and Duke Divinity School professor Lauren F. Winner.
Its main ritual involves a priest invoking ("for you are dust, and to dust you shall return") while anointing congregants' foreheads with a mix of ash from Palm Sunday—itself derived from the story of Christ's route to Jerusalem being padded by palm fronds—and sometimes oil. Lent is an acknowledgment of the 40 days Christ spent in the wilderness. Since Ash Wednesday kicks off Lent, its date is always exactly 46 days before Easter (fasting is ) and thus is affected directly by what date Easter falls on that year.
Which brings us to our central question: Why is Easter on a different date each year? The holiday, which celebrates Christ's return from the grave following his crucifixion, usually occurs between March 22 and April 25. It's set to coincide with the , a day when the sun shines directly on the equator and the majority of earth experiences nearly equal hours of sunlight and nighttime, which signals the in the norther hemisphere. Because Christ's death and resurrection happened after the Jewish Passover, which is celebrated on the first full moon after the equinox, early Christians wanted Easter to always take place following Passover, according to To make a long answer short, Easter falls on a different date each year because it, like Passover, is tied to solar and lunar cycles.