Easter and the Paschal Full Moon

The Curious Link Between Easter, the Equinox, and the Moon

April 18, 2019
Spring Moon
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A “Pink Easter Moon” will rise the morning of Good Friday! Did you know that the date of Easter—April 21 this year—is tied to the full Pink Moon and the Vernal (Spring) Equinox? Understand the curious connection …

Easter and the Paschal Full Moon

Easter is what’s known as a “movable feast”—in other words, a religious holiday that falls on different calendar dates from year to year.

See our EASTER PAGE to learn how to calculate the date of Easter.

The date of Easter is tied not only to the full Moon, but to the Vernal Equinox and the relationship between them, too. Thanks to this, determining when Easter will be can get more than a bit confusing.

Here’s the basic rule for finding the date: 

Easter is observed on the Sunday following the Paschal Full Moon, which is the first full Moon that occurs on or after the Vernal Equinox.

For example, if the Vernal Equinox occurred on March 21 and the full Moon occurred on March 23, Easter would be observed on the first Sunday after March 23.

However, that is really putting it too simply…

Photo by jakkapan/Shutterstock

Differing Dates

The biggest cause of confusion regarding Easter is the tangled web of dates that are used to determine the holiday. If you take the rule given above at face value, things don’t always work out quite right.

This is exactly what happened in 2019. The Vernal Equinox occurred on March 20 at 5:58 P.M. EDT, with the full Moon reaching its peak four hours later, at 9:43 P.M. EDT. But wait—that means that the full Moon and the Vernal Equinox happened on the same date, which should have landed Easter on Sunday, March 24, right? Well, not quite.

The dates of the full Moon and the Vernal Equinox that are used to calculate Easter are not the astronomical dates of these events, but rather the ecclesiastical dates. 

  • The astronomical dates of the full Moon and the Vernal Equinox are the actual, scientifically determined dates of these events. For example, the Vernal Equinox occurs at the exact moment when the Sun crosses Earth’s equator, when day and night are approximately equal. Similarly, the full Moon occurs when the Moon reaches peak illumination by the Sun.
  • The ecclesiastical dates of the full Moon and the Vernal Equinox are those determined long ago by the Christian Church, and they may differ from the actual dates of these events.

In A.D. 325, a full Moon calendar was created that did not take into account all the factors of lunar motion that we know about today. The Christian Church still follows this calendar, which means that the date of the ecclesiastical full Moon may be one or two days off from the date of the astronomical full Moon. 

Additionally, the astronomical date of the Vernal Equinox changes over time (it may occur on March 19, 20, or 21), but the Church has fixed the event in their calendar to March 21. This means that the ecclesiastical date of the Vernal Equinox will always be March 21, even if the astronomical date is March 19 or 20. 

Due to these rules, in 2019, the ecclesiastical full Moon occurred before the ecclesiastical Vernal Equinox, which meant that Easter would not be observed until after the next full Moon (the Paschal Full Moon) in mid-April. Thus, Easter will be held on Sunday, April 21, this year. 

Fun Fact: “Paschal” stems from Pascha, the Greek and Latin word for Passover.

How Late Can Easter Be?

For the western Christian churches and others that use the Gregorian calendar for their calculations, Easter can occur as early as March 22 and as late as April 25.

For the Eastern Orthodox churches and others that use the Julian calendar for their calculations, the observance can occur between April 4 and May 8 in the Gregorian calendar. 

Interestingly, Easter Sunday will remain in April for the next four years. It won’t be in March again until 2024!

Learn more about how to calculate the date of Easter.

Which Full Moon is Nearest to Easter?

The full Moon nearest to Easter can change. Sometimes, it’s the full Moon which falls in March and sometimes it’s the full Moon which falls in April.

Both tonight (April 18) and tomorrow (April 19), you’ll see a round full-looking Moon.

See more information about April’s Full Pink Moon!

2019 Moon Wall Calendar

Want to enjoy the beautiful Moon year-round? Check out our 2019 Moon Wall Calendar!

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