Basti93 / Pixabay

The Earth Epic Calendar has mostly based itself on factors of one hundred, but this gets tricky with a year that has 365 or 366 days per year. However, if we divide the year into equal quarters, we get 91 or 92 days each, which is close to 100.

As I said previously, Quarters are tied to the solar year, Months track the lunar cycle and are thus independent of the solar year.  A big advantage of of using Quarters is that since every Quarter has about thirteen weeks, it makes it easier to use the calendar to plan weeks ahead of time without having to turn the calendar page.

It’s worth noting that dividing the year into Quarters is similar to the World Seasons Calendar proposed by science fiction writer Isaac Asimov (Asimov, I. (1973). The Tragedy of the Moon. United Kingdom: Doubleday..) It should also be noted that due to the elliptical nature of the earth’s rotation, the lengths of the astronomical seasons vary from lengths of the Quarters described in this calendar—astronomical spring, summer, fall and winter currently vary in length between 88-93 days.

Unlike Asimov’s calendar, the first day of the year is not tied to a specific date on the Gregorian calendar but begins at the midnight close to the time of the astronomical winter solstice in the Northern Hemisphere. On the Gregorian calendar, this day is currently either December 21 or 22.

Aligning the new year with an astronomical event rather than a simple cycle is also done with the Solar Hijri calendar used in Iran and Afghanistan  The solar new year in that calendar is at the midnight closest to the astronomical spring equinox. The Solar Hijri calendar– not the Gregorian calendar, you Eurocentrists–is the most accurate calendar currently in use in the world. Both calendars and the Earth Epic Calendar have 365 days in regular years and with 366 days in leap years.

The Gregorian calendar sets its leap years at regular four year intervals, with exceptions made for years ending in 00 where the century is not divisible by four (i.e. 1700, 1800, 1900, 2100). However, by simply tying the first day of the year to the actual day of the winter solstice, the Solar Hijri and the Earth Epic calendars never vary more than about a half day from the actual completion of one Earth orbit around the sun.

With the Earth Epic and Solar Hijri calendars the interval between winter solstices determines the exact number of days in the year. Like the Gregorian Calendar, the interval is either 365 or 366 days, but this also means that the incidences of the leap year are slightly more irregular in the Solar Hijri and Earth Epic Calendars than in the Gregorian Calendar. Most of the time,  four years pass between leap years, but occasionally the interval is five years. In the Earth Epic calendar, the last leap year was 11.717 (starting on 12/21/2016) and the next one will be on 11.721 (starting on 12/21/2020). The last five year interval between leap years was between 11.708 and 11.713 and the next one will be between 11.741 and 11.746.

The Earth Epic Calendar sets the first day of the year at the Winter Solstice (rather than the Solar Hijri’s Spring Equinox) for several reasons. First, the adjustment from the Gregorian Calendar—the mostly widely used calendar in the world—is less difficult because the first day of the year in the Earth Epic calendar is just 10 or 11 days before the first day of the year in the Gregorian calendar, making adjustments easier. The Winter Solstice also coincides with holidays for many religions and cultures. This time is also often the midpoint between the autumn harvest and the spring planting season for much of the world, given that 90% of human beings live in the Northern Hemisphere.  This period around the Winter Solstice is often a time for reflection.

Local cultures should name the quarters in this calendar however they wish.  I spoke before as to how the worldwide adoption of the Gregorian calendar is a reflection of cultural imperialism.  Letting local cultures name the quarters would be a way to let them reclaim the calendar while still providing accuracy and uniformity of standards worldwide.

Even though local cultures should determine the name of the quarters as they deem appropriate, a worldwide standard is needed so that different cultures would have a common frame of reference.  For this worldwide standard, the names Southlight, Westlight, Northlight and Eastlight describe the Northern Hemisphere’s winter, spring, summer and fall (and the Southern Hemisphere’s summer, fall, winter and spring). The first day of Southlight (and the first day of the year) starts at the December Solstice when the concentration of sunlight is greatest and at its peak in the Southern Hemisphere, and Northlight starts around the June Solstice when the concentration of sunlight is the greatest and at its peak in the Northern Hemisphere.

Westlight and Eastlight both start close to the March and September equinoxes.  While Southlight and Northlight reference the Sun’s position relative to Earth, Eastlight and Westlight are more metaphorical when referencing the Sun’s position.  With the North at the top of the compass and the South at the bottom of the compass, West is the next step clockwise from South, so  Westlight comes after Southlight. Likewise, East is the next step clockwise from North, so Eastlight would come after  Northlight.

Since four quarters of 91 days equals 364, we need to figure out where to put the extra day so that the year totals 365 days, and where to put the leap day during leap years.  Asimov’s calendar puts the extra day at the end of the year and the leap day at the end of the second quarter.  But in the Earth Epic Calendar, each year has an extra day at the end of Northlight (the summer, or third quarter of the year), during September in the Gregorian Calendar.  During leap years, an extra day is added to the end of Eastlight (roughly the spring, or second quarter of the year), during June in the Gregorian calendar.

Why these times?  It’s because the Earth’s orbit around the sun is elliptical, rather than a perfectly round circle with the Sun in the center. Currently, summer in the Northern Hemisphere is the longest season, followed by spring in the Northern Hemisphere.  Consequently, the Earth Epic Calendar adds a day quarter covering the Northern Hemisphere summer–Northlight, and the leap year day is added to the end of Eastlight during leap years.  This keeps the length of the quarter close to the length of the astronomical season.

Axial precession and leap days
Impact of Earth’s axial precession and elliptical orbit on the lengths of seasons.
Image By Cmglee – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30359851

It is worth noting that the date where the extra day and leap day are assigned will change roughly four times per Calendar Epoch, or roughly every 6,500 years.  This is because the length of astronomical seasons change due to the axial precession.  As such, autumn will be the longest season, with summer being the second longest, around 7000 CE (16.700 EE), which will necessitate placing the extra day at the end of Westlight (in December) and the leap day at the end of Northlight (in September).  Winter will be the longest season around 12,000 CE (21.700 EE) which will necessitate putting the extra day at the end of Southlight (in March) and the leap day at the end of Weslight (in December).

—> forward to

<— back to Millennium and Year

(return to The Calendar Time Scales)