In 1583, Queen Elizabeth’s court, not wanting to adopt the catholic Gregorian calendar, commissioned John Dee to create a calendar for the British Isles. He did it, and he did it brilliantly. And even though it was far more accurate than the Gregorian calendar, John Dee’s calendar was never adopted.
The design John Dee used to create his calendar was interesting. It proposed a meridian that started from Washington, DC. Even though the calendar was never adopted, the 77th parallel is the corner of the Capitol Building in Washington. And though never officially used, it became known as God’s Latitude, also running through Cuba, Jamaica and Peru.
John Dee’s proposal captured the fact that it was the place where light and dark occurred equally at exactly the vernal equinox for over 300 years, and it was in a location that medievalists, including John Dee, considered “the New Jerusalem”.
The location where the light is equal during the equinox shifts as we move through our solar system and today it continues to move eastward.
Thus God’s Longitude now exists at this band of longitudes around 74°30’ W. Consulting a map of the world we find that New York City (73°58’), Bogota (74°5’) and Guantanamo Bay (75°14’) are all within this band. – Peter Meyer
I talk about this more in my post Is Time Really Off.
Is Time Really Off?
The Gregorian calendar has been blamed for throwing us off.
Now, the reason that I bring this up is that if the moment of equal light and dark was such a big deal to the medievalists and obviously, also to the master builder Masons, then it seems that there would be some precision around just when that moment occurs.
Recently, thanks to this post by Schoepffer, I’ve been thinking a lot about Equinox vs Equilux. Equilux, as Schoepffer points out, is the actual day of equal light and dark – and he’s been tracking it with his naked eye, and he’s got a handy link to an app to help confirm.
I asked AI to summarize the difference between the two
Equilux is the date when day and night are of exactly equal length, each lasting approximately 12 hours. Unlike the equinox—where day and night are nearly equal
Hold up… what????
The equilux accounts for two key astronomical factors: the Sun’s large apparent size (a disk, not a point) and atmospheric refraction, which causes sunlight to bend and makes the Sun visible before it fully rises and after it has set.
As a result, daylight is slightly longer than night on the equinox, meaning the true balance of 12 hours of day and 12 hours of night occurs a few days before the spring equinox and a few days after the autumn equinox in the Northern Hemisphere (and vice versa in the Southern Hemisphere).
The exact date of the equilux varies by latitude:
In the UK, the spring equilux occurred on 17–18 March 2026.
At the equator, there is no equilux, as daylight exceeds 12 hours every day.
The equilux is not a fixed global event—it depends on location and is calculated based on sunrise and sunset times.
The term “equilux” comes from Latin: equi- (equal) and lux (light), meaning “equal light.”
This got me thinking… Did the ancients distinguish between equinox and equilux? I asked again….
Practically, many ancient observers likely identified the equinox by watching when sunrise and sunset were closest to due east and due west, and when day and night seemed equal in length. That observational practice comes closer to what is now called equilux, but they still conceptualized it under the single idea of the equinox.
Soooo…
The concept of equilux was created in the 1980’s. Essentially, equinox was redefined. What we, the average person, and the medieval and ancient astronomer consider as equinox, is now called equilux.
And it’s three (3) days earlier than the newly redefined “equinox”!
Side rant… It’s just one more way in which we are asked not to believe our eyes! It’s why I encourage everyone to go out under the sky and experience it for themselves.
The day when equal day and night occur matters because the constellation that we look at on that day defines the great age…. The precession of the equinox means that the stars move backwards as we move through the great age, and if we arrive at equal day and night three days earlier, it means we are that much closer to the age of Aquarius.
The day of equal night and day depends on your location, as mentioned above. Yet, regardless of the location, it’s earlier than March 20th. And just as the zodiacal constellations that we are so familiar with today were defined by those in the Middle East and North Africa, so were the ages. Using their location, we can likely distinguish what they saw at the equinox and what defined the beginning of an age for them within the current constellational system that we use. And… Likely, it was different for cultures at different latitudes and with different sky cultures.