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Why is Easter so late this year?

April 20, 2019 GMT

Easter can fall anywhere from March 22 to April 25, and it can feel like Christmas or the Fourth of July.

Those little Easter-egg hunters could freeze while scurrying around the backyard one year and risk heat stroke the next. Their chocolate-egg treasures could either chip a tooth or melt in their little hands.

This year, Easter falls on April 21.

Why does Easter move around so much? Its date is determined through a combination of the lunar phase and the spring equinox, with a slight twist that can cause some confusion, particularly in years like this.

Generally speaking, Easter falls on the first Sunday following the first full moon after the vernal (spring) equinox, according to Catholic.com. If the first full moon happens on the equinox, Easter is the following Sunday.

Here’s the twist: The vernal equinox can fall on one of three days, March 19, 20 or 21. For the purposes of determining Easter, it’s assumed that the equinox arrives on March 21.

Among those thrown off by the twist this year was amateur astronomer Dave Huestis, a columnist and member of Skyscrapers Inc., a group of amateur astronomers who operate Seagrave Memorial Observatory in North Scituate.

Knowing that the spring equinox would arrive on March 20, Huestis expected Easter to fall on Sunday, March 24.

“When I looked up the date for Easter 2019 (April 21) I immediately realized something was not right,” Huestis wrote in his monthly column. “When one has followed the motion of the heavens for as long as I have, you can anticipate when and where events will happen. Being well aware of the ‘formula’ for determining the date for Easter, I initially expected it would fall on Sunday, March 24.

“Why? This year the vernal equinox was on Wednesday, March 20, at 5:58 p.m. EDT (Eastern Daylight Time). The full moon on or after that date occurred on the same day at 9:43 p.m. EDT. Therefore, I calculated that Easter would be observed on the following Sunday, March 24, almost as early as it can be celebrated.

“So why was my reasoning incorrect? Because of the fact that the vernal equinox date does vary, the Easter date depends on the ‘ecclesiastical approximation of March 21 for the vernal equinox’ according to https://www.timeanddate.com/calendar/determining-easter-date.html. This stipulation holds true even if the vernal equinox falls on the 19th or 20th of March.

“Considering this additional qualification using March 21 as the date for the vernal equinox, the next full moon after March 21 will be on April 19 this year. Therefore, Easter will be celebrated on Sunday, April 21.

“It is always a great day when you learn something new!”