Equinoxes are bitter–sweet–indifferent events the world over.  It’s the day that marks the arrival of autumn in one hemisphere (potentially bitter for some as they tumble towards winter!) and spring in the other (very sweet for those who are trying to clamber their way out of winter’s frigid talons).  For the millions who live in subtropical regions they will be quite indifferent to this solar event. 

The equinox will happen at 17h58 (5:58pm) EDT or 15h58 MST on March 20^th, 2019.  This is the occasion when the longitude of the sun is exactly 0° and 180°, the day when the sun will have risen precisely due east and will set precisely due west.  As Rob Berman comments so neatly in his blog post about this event, it’s the perfect day to recalibrate your sun dial! 

What about the moon?

The 2019 event will be a extra-special because we will enjoy a full moon – and the third and final super-moon of 2019 – which will rise on the eastern horizon just as the sun sets to our west!  So, if you’re a photograph fanatic and you’re enjoying cloudless skies today, head out to some unobstructed hilltop viewing sight to enjoy our greater and lesser lights in all their glory at sundown (estimated at 19h49 MST)!

The fact that I have seen a robin in our back yard this week – the first of the season – confirms the other interesting trivia that Catherine Boeckmann highlights in her blog, and that is the name of the spring full moon.  Referred to, in some circles, as the Full Worm Moon, it is an indicator of when the ground may begin to thaw and soften, triggering earthworms to reappear and the robins to being their spring smorgasbord! 

It’s rare that the ground in Calgary begins to thaw until sometime in April, but for now we certainly are enjoying some unseasonably warm temperatures following our weeks of being gripped in a relentless polar vortex.  So, we joined the robins and neighbours outdoors last evening for our first barbecue of the season in defiance of the inevitable snow dumps we’ll still encounter as spring displaces winter in the weeks to come and life begins to surge back into our gardens, neighbourhoods, parks, prairies and mountains.  It’s also why this is known as the Full Sap Moon, the time of year when the sap of sugar maples begins to flow.

The impact on Easter

Interestingly, this rare coincidental event has also affected the date when Easter will be celebrated in 2019.  In most years Easter falls during the month of March, the first Sunday after the full moon of the vernal (spring) equinox.  As summarized by Boeckmann, “Since the full Moon AND the vernal equinox both fall on March 20^th this year (in North America, at least), you might expect that Easter Sunday would be on the following Sunday, March 24^th. 

However, for simplicity’s sake, the Church set a fixed date for the equinox, March 21^st.  Additionally, the Church does not rely on the date of the astronomical full Moon, but rather the ecclesiastical full Moon, which occurs on the 14^th day of the ecclesiastical lunar month. The date of the ecclesiastical full Moon may fall one to two days before the astronomical full Moon. Therefore, because the first full Moon after March 21^st doesn’t occur until April 19^th this year, Easter Sunday 2019 falls on Sunday, April 21^st! 

(This is not the first time the church’s “set” equinox and astronomy’s “moving” equinox affected Easter’s date; it last happened in 1981 and will happen again in 2038.)”

Happy Equinox, World!