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The Full Worm Moon


With Spring almost upon us, it is evident everywhere we look that Mother Nature is starting to awaken after her long Winter slumber. With the warmer temperatures, the earthworm is starting to be active again, breaking up the soil as it tunnels its way to the surface. This is a much welcome breath of fresh air for roots, as not only does the tunnelling allow oxygen to permeate the soil, but it allows the roots to penetrate deeper to reach much needed nutrients. Worms eat anything they can digest, such as leaves and grass, which in turn creates worm casts on the surface, attracting the Thrush and Robin to search for such tasty morsels. There’s something quite magical about digging the garden and having to stop whilst a Robin flies in, quite close to your fork, to make a grab for a worm.

Such a valued contributor to the soil ecosystem is therefore understandably worthy of note by the Native Americans as a descriptive of the last full moon of Winter and a mark of Spring to come. This full moon is also known as the “Sap Moon”, marking the time when Maple Trees are “tapped” for their sap to transform into maple syrup and sugar. In Springtime, when the nights are still cold, water from the soil is absorbed into the maple tree. During the day, the warmer temperature creates pressure that pushes the water back down to the bottom of the tree, making it easy to collect the precious maple sap. This process was passed on from the Native Americans to the early settlers, and is still popular today.

In the UK (London), the Worm Moon reaches its fullness at 01:42 on 21 March 2019, almost four hours after the Spring Equinox (21:58 hrs Wednesday, 20 March 2019). We’ve traditionally celebrated the beginning of Spring as March 21st and personally, I’ve always thought this to be the case as long as I can remember, so it’s interesting to identify that it isn’t always that way and to discover why.

As the Earth revolves around the Sun, there are two moments each year when the Sun is exactly above the Equator, called Equinoxes, when the days and nights are of equal length. In the Northern Hemisphere, the “Vernal Equinox” can occur at any time between March 20th or 21st and is called the “Vernal Equinox”, as it marks the first day of Spring. The September Equinox is called the Autumnal Equinox as it heralds the first day of Autumn.

Why Do the Dates Change?

The March Equinox would occur on the same day every year if the Earth took exactly 365 days to make a complete revolution around the Sun, but this is not the case. It takes the Earth about 365.25 days on average to go around the Sun once. The Gregorian calendar accounts for this by adding an extra day – the leap day – almost every 4 years. This means that each March Equinox occurs about 6 hours later than the previous year's March Equinox. This is why the date of the Equinox can change from year to year.

The Vernal Equinox is also used by Christians to identify the timing of Easter Sunday (the day of Christ’s resurrection). According to the Bible, Jesus Christ's death and resurrection occurred around the time of the Jewish Passover, which was celebrated on the first Full Moon following the Vernal Equinox. (Referred to as a “Paschal Full Moon”, Paschal being derived from "Pascha" a transliteration of the Aramaic word meaning Passover).

However, there was some uncertainty as to which calendar was used to determine this date. The current day Gregorian solar calendar, as noted above, is based on the revolution of the earth around the Sun, but Lent, being the six week period leading up to Easter, is a Lunar calendar, based on the cycle of the Moon.

An article by Matthew Cooper in a recent copy of the Manchester Evening news explains how it works:

Why does Easter change every year and who decides the date?

While many festivals are on fixed days, Easter is a movable feast and is usually celebrated on the first Sunday after the full moon on or after March 21, because it is based on the lunar calendar.

The First Council of Nicaea was a council of Christian bishops convened in Nicaea in Bithynia by the Roman Emperor Constantine I in AD 325. They made decisions in an effort to attain a consensus on several Christian topics. Based on the Paschal full moon, it was decided by the bishops that Easter Day would fall on the next full moon after the spring Equinox. The Paschal full moon was chosen because the date of Passover in the Jewish calendar, and the Last Supper (Holy Thursday) occurred on the Passover. Therefore, Easter is the Sunday after Passover. Since the Paschal full moon can be on different days in different time zones, it was decided that the full moon is always determined to be the 14th day of the lunar month. Even though the spring Equinox can occur on March 20 the Church also fixes the Spring Equinox as March 21.

With the first “Paschal full moon” after March 21st falling on Sunday 14 April, the first Sunday after that date is Sunday 21st April, which is why Easter Sunday is so late this year.

I didn’t write this blog with the intention of researching the Vernal Equinox; associated moons; ecclesiastical tables and history, but once into it, found it fascinating. It’s a wonderful feeling to completely lose yourself in something and for time to completely disappear – similar to meditation, which is the subject I had intended to follow up on, but will now have to save for another day!

I do hope you have found this article interesting and would love to hear any thoughts you might have in response.

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