Why Does Easter Change Dates Every Year?

(Last Updated On: April 4, 2021)

Why does Easter change dates every year? How is this date even determined? And why do we celebrate Easter in the first place?

Why Do People Celebrate Easter?

We all know about the light-hearted traditions that come with Easter that serve as familiar markers of the onset of spring. Most people in America, whether Christian or not, get swept up in the fun that is Easter. The traditions that have evolved over the years, including the Easter eggs, bunnies, and candy, can be especially popular with children who look forward every year to the annual Easter Egg Hunt.

What many people fail to realize is that Easter is actually the oldest holiday in the Christian religion and is totally foundational to the faith. It is celebrated on Sunday because this is the day that Jesus was resurrected from the dead. According to the Christian New Testament, he spent three days in a tomb after being crucified only to emerge from his grave on Easter Sunday.

According to the tradition set out by Pope Gregory I, the lead up to Easter is a 40-day period of fasting called Lent, which commemorates the time that Jesus was said to have spent in the wilderness enduring the temptation of Satan. The day the fasting begins is referred to as Ash Wednesday and the day the fast ends is called Good Friday. Good Friday always falls on the Friday just before Easter and marks the day that Jesus was crucified. According to the Christian tradition, these events were God’s prophecy and represent Jesus’s gift to humanity, the gift of eternal life.

So the question remains, why does Easter change dates every year?

Why Is Easter Celebrated on a Different Day Every Year?

Given that Easter is the single most important feast that is celebrated on the Christian calendar, it may seem a bit strange that Easter doesn’t have a set date. In fact, Easter may even occur in different months from year to year. While Easter is always held on a Sunday, the celebrations may take place any time between March 22nd to April 25th.

Even more complicated, some churches in the Eastern Orthodox Tradition that don’t follow the popular Gregorian calendar, but instead follow the Julian calendar, have a totally different date range for Easter, between April 4th and May 8th.

Either way, why exactly does Easter have a possible date range of over a month? The answer lies in the fact that Easter is a “movable feast.” This means that Easter doesn’t have a fixed date, but changes according to the timing of the full moon. While there are other movable feasts in the Christian tradition, Easter is used as the benchmark by which all the other moveable holidays are synced according to.

How Is Easter’s Date Determined?

The specific formula for determining where Easter will fall on a year-to-year basis is to first determine the date of the full moon that occurs either on or after the spring equinox, which is otherwise referred to as the “vernal equinox.” The spring equinox is commonly used as a reference to mark the beginning of spring. Easter’s date is the first Sunday after the first full moon on or after the equinox.

So what are equinoxes? Equinoxes are dates that occur only twice a year and are used to mark those points in time when the center of the visible Sun is directly above the Equator. In more general terms, we tend to think of an equinox as a day and night of almost equal length. In fact, “equinox” actually comes from a Latin word that means “equality of night and day.” Since the sun crosses the equator moving north on the vernal equinox, the result is that the Northern Hemisphere starts to experience longer and sunnier days after this point.

The spring equinox in Christianity is celebrated on March 21st, although scientifically speaking it can take place at any time between March 19th and the 21st depending on the year. Since the full moon occurs on or after the equinox, but Easter’s date has to fall after the full moon, the first possible date for Easter is on March 22nd, one day after the Christian Equinox. The date range is over a month because the full moon occurs on average just under every 30 days, and Easter can fall up to seven days after the full moon.

What Day Does Easter Fall on in 2021?

Interestingly enough, Easter falls on April 21st this year, which is in the latter portion of the possible date range. However, the full moon and the spring equinox technically fall on the same day this year, March 20th. So what gives? Shouldn’t Easter fall on the Sunday after this full moon?

Let’s not forget that in Christianity, the equinox is always celebrated on the 21st. This means that the full moon that happens on the scientific equinox doesn’t count since it falls before the 21st of March. The next full moon happens on April 19th, and since this is the full moon directly after the Christian equinox, it is the one used to calculate the date of Easter. And this is why Easter is occurring on a later date this year.

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