The Calendar Time Scales

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The Calendar Time Scales reference the units of time people are usually most familiar with seeing on the calendar.  The units of Millennium, Year, and Day are familiar, and are affixed to the orbit of the Earth around the Sun and the rotation that makes up one day.

The Earth Epic Calendar is unique in that in addition to being a solar calendar, it also tracks lunar cycles. But it doesn’t tie the lunar cycle together with the solar cycle.  Instead, the Earth Epic calendar divides the year into four Quarters of 91-92 days each and these are tied to the solar cycle. Months are in the in the Earth Epic Calendar, too, but unlike quarters they are NOT tied to the solar cycle–they exclusively serve to track the cycles of the moon, which was their original purpose in ancient calendars.

The oldest calendars were lunar calendars that measured the time between full moons.  The average length of time between full moons is 29 1/2 so the length of lunar months on these calendars would alternate between 29 and 30 days.  But twelve lunar months equals 354 or 355 days, while the length of the year is 365 or 366 days.

To understand the problem with  tying together the lunar and solar calendars, it’s helpful to look at the challenges brought by the most widely used lunar calendar today–the Islamic Calendar. Many, but not all Muslims believe that God prohibits intercalary days or months to adjust the calendar to the solar year.  The Islamic calendar has twelve lunar months per year, which means that the Islamic year is 354-355 days per year, unlike the solar Gregorian calendar which has 365-66 days per year.  But there is a Muslim calendar that allows intercalary days (but not months)–the Solar Hijri Calendar used primarily in Iran and Afghanistan. This calendar is actually the most accurate solar calendar in the world, even more so than the Gregorian calendar.  Both the Islamic and Solar Hijri calendars date their calendar from the Hegira (Hijra)  in 622 CE. But because the lunar year is shorter than the solar year, in the spring of 2020 CE it was the year 1441 AH in the Islamic calendar, but 1399 SH in the Solar (Shamsi) Hijri calendar.

Many ancient calendars have tried to reconcile the solar and lunar cycles, including the Hebrew, Babylonian, Hindu, Coligny (Gaulish Celtic), Attic (Athenian), Assamese, Chinese, Egyptian, Jain, Tibetan, and Vietnamese calendars, as well as others.  In order to keep the lunar month intact, these lunisolar calendars have tried to reconcile lunar and solar cycles by adding a thirteenth month to the calendar in select years.  That is, rather than adding extra days to certain months, they would add an extra month (and therefore 29 or 30 days) to certain years. The most well known and perhaps most accurate effort was a system known as the Metonic cycle, a cycle that is 235 lunar months long and just 1 hours, 27 minutes and 33 seconds longer than exactly nineteen years on the Gregorian Calendar.

But the lunisolar calendar system has a number of problems.  The first and most obvious problem is that adding 29 or 30 days to a year can certainly throw off the annual cycles that many people find it necessary to keep track of.  The second is that while the length of of Earth’s orbit around the Sun has stayed quite constant, that’s less true of the Moon’s orbit around the Earth.  The Moon is gradually moving away from the Earth, and as a result, the length of the orbit of the Moon around the Earth will increase.  Thus, the currently established Metonic cycle will eventually stop being an accurate way of reconciling the lunar orbit with the solar year.

To better address this problem, the Earth Epic Calendar keeps the solar and lunar cycles separate.  The Quarters are tied to the Earth’s orbit around the Sun, and the Months are tied to the Moon’s orbit around the Earth.  The Months are not at all tied to the first day of the New Year on the Earth Epic Calendar but operate independently.

As such, the six units of time measured within the Calendar Time Scales are as follows:

Millennium (1,000 years)

Year (4 quarters or 365-366 days)

Quarter (91-92 days)

Month (29-30 days)

Week (7 days)

Day (same length as Gregorian calendar)