Why Is Easter 2019 So Late This Year? Blame It On The Moon

    05.07.19 |

    When is Easter in 2019?

    In 2019, Easter falls on Sunday, April 21st. You probably already knew that Easter falls on a different date each year… but why?

    Why Does It Fall On A Different Date Each Year?

    Easter and the many church holidays related to it—such as Ash Wednesday, Palm Sunday, Good Friday—are called “moveable feasts,” because they do not fall on a fixed date on the Gregorian calendar, which follows the cycle of the Sun and the seasons. Instead, these days follow a lunisolar calendar, similar to Jewish holidays.

    How Is The Date of Easter Determined?

    According to a Fourth Century ruling, the date of Easter is set for the first Sunday following the Paschal Full Moon, which is the first full Moon of Spring, occurring on or shortly after the Vernal Equinox. March 22 is the earliest Easter can occur on any given year, and April 25 is the latest.

    Why Is Easter So Late in 2019? Blame It on the Moon.

    Wednesday, March 20, 2019, marked an interesting day on the celestial calendar. First, at 5:58 p.m. Eastern Time, spring officially began in the Northern Hemisphere with the arrival of the Vernal Equinox.  Then, 3 hours and 45 minutes later, at 9:43 p.m. Eastern Time, March’s Worm Moon turned officially full. What does this have to do with Easter? Read on!

    Because the Moon officially turned full after the occurrence of the vernal equinox on March 20th, it was the first full Moon of the spring season. But had the Moon turned full a mere one minute before the equinox, it would have been categorized as a winter full Moon. But having occurred shortly after the moment of the equinox allows it to have the title of the first full Moon of spring. And this has some interesting consequences.

    when is easter

    The Rules?

    When the Christian holiday of Easter Sunday falls on the calendar is determined by the Moon. The rule states that Easter is observed on the Sunday after the first full Moon of spring, the so-called “Paschal Moon.” If that first spring full Moon occurs on a Sunday, then Easter will be observed on the following Sunday.

    So, according to the rule above, if the first full Moon of spring occurred on Wednesday, March 20th, it would stand to reason that Easter 2019 should have taken place the following Sunday, March 24th, right?

    But it doesn’t, because of two ecclesiastical rules – rules that pertain to the Christian Church and its clergy.

    Rule #1 – The Golden Number

    First, there is the dating of the full Moon. Astronomers can tell us precisely to the exact minute when the Moon will arrive opposite the Sun that will brand it as a “full” Moon. However, the Church follows its own methodologies in determining when the Moon turns full. One important factor is something called the “Golden Number.”

    It is a rather arcane series of computations that in the end provides a date for Easter. Of course, on occasion, the date for the full Moon does not exactly line up with the date that is provided by astronomy.

    Rule #2 – Ecclesiastical Spring

    Second—and this is the primary stumbling block for this year—is that from the ecclesiastical perspective, the first day of spring falls on March 21st. (It is said that March 21st was selected as the ecclesiastical vernal equinox because the Church of Alexandria, whose staff were reputed to have astronomical expertise, said that March 21st was the date of the equinox in 325 AD). But the date of spring differs in astronomy. In our lifetimes, for the longitudes of North America and for Europe, spring won’t arrive on March 21st until the year 2102.

    So this year, since our March full Moon falls on the 20th and not the 21st, it is not recognized as the Paschal Moon by the Church. So, we must wait until the next full Moon, on April 19th. That day is also Good Friday and that evening is the first night of the Jewish feast of Passover. Finally, on Sunday, April 21st, we will celebrate Easter Sunday. That’s within four days of the latest possible date for this moveable holiday.

    – Contributed by Astronomer Joe Rao

    Here’s a look at some of the upcoming dates for Easter:

    2019   April 21
    2020   April 12
    2021   April 4
    2022  April 17
    2023  April 9
    2024  March 31