Keeping the 364-day Calendar Year On Track with the Solar Year - Part 2
In part 1, we discussed "intercalation" - its definition and its absolute necessity in any calendar system. Now in part 2, we examine a fundamental criterion for intercalating the 364-day calendar that is generally somewhat misunderstood - the vernal (Spring) equinox. It is not unusual for us to observe some degree of ambiguity as to what the equinox actually is and how it should be applied with the Zadokite Sabbath Calendar.
BEGINNING OF MONTHSCYCLES OF TIME
Part 2 - the Vernal (Spring) Equinox
A recap of where we ended in Part 1:
1 Enoch 72:32*
(32) On that day the night decreases and is nine parts, with a daytime of nine parts. Daytime is equal to the night, and the year is exactly 364 days.
*1 Enoch: The Hermeneia Translation by George W.E. Nickelsburg & James C. VanderKam, copyright 2012, Fortress Press, p.99
In this quote from the book of 1 Enoch, we see that the equinox (the context in this passage is pointing to the vernal equinox) marked a completion of a year that was an exact 364 days. This would have been before the flood of course, and it may have even existed up until the time of Joshua's long day (Joshua 10:12-14) and King Hezekiah's sundial (2 Kings 20:9-11). We can't say for sure that the year was originally 364 days, but these things all come together to give us a highly reasonable explanation for what we are dealing with now in the length of a year. Regardless of the questionable reliability of 1 Enoch, we can be sure that the vernal equinox is still our most stalwart and objective indicator for the end of a solar year, ...
Technically speaking however, 1 Enoch is describing an equinox in terms of equilux (equal light) which occurs near the time of equinox, but its observation can vary by several days from the equinox according to one's latitude on the planet and local times for sunrise and sunset. Equilux is an inconsistent and unreliable "yardstick" to measure the completion of a yearly cycle, and true equilux is impossible to calculate without the precision of modern timekeeping devices such as clocks. Ancient societies had no means of knowing the exact lengths of day and night down to the minute like we have today. An equinox, on the other hand, is a solar event that happens uniformly, consistently and reliably every year, and ancient knowledge of the sun's shadow was all that was needed for its observation. You can read more about these two similar events in our article Equinox or Equilux - Which Do We Use?
The vernal equinox is 1 of 4 solar events (2 equinoxes + 2 solstices) that occur every year as our great "blue marble" orbits the sun. As a result, we have 4 distinct seasons that are opposite of each other according to latitudes north of Earth's equator as compared to latitudes south of the equator. The plane of Earth's equator and its relative position to the plane of our celestial orbit around the sun is the defining characteristic of these 4 solar events. Here is a nice diagram from timeanddate.com to help illustrate:
Please understand that equinoxes and solstices are strictly solar events; they are defined by the positioning of the earth's equator in relation to the celestial plane of its orbit around the sun. While the stars and their constellations also have a relativity in their seasonal positions to the earth and the sun, they do not define the seasons. Stars and other celestial bodies (the moon, other planets) do not have any direct cause or affect on equinoxes and solstices. These other bodies are merely part of the background, part of a greater cosmic relativity that does not guide the seasonal transitions here on planet Earth. Equinoxes and solstices are solely determined by the tilt of the earth's axis and the juxtaposition of the sun's light and heat being radiated toward Earth as the planet makes its yearly orbit:
The solstices mark the maximal extremes that result from the earth's tilt in contrast to the sun. Our equator is at its maximum deviation away from the celestial plane of the sun at the time of a solstice. The earth's equator is either at its furthest point below the celestial plane (June) or at its furthest point above the celestial plane (December). This is when we experience the longest and the shortest periods of daytime and nighttime, and we see the sun at its highest or its lowest points in the sky for the year. Each solstice marks a beginning of either the warmest season (summer) or the coldest season (winter) of the year with the northern and southern hemispheres experiencing the extremes of winter or summer inversely (opposite of each other).
Equinoxes come at a midway point between the two solstice extremes when the equator is crossing over the celestial plane. When the vernal equinox occurs, the equator is lined up perfectly with the sun, neither above or below the celestial plane. The earth's equator is at a point of intersection with the celestial plane, crossing through it as earth is about halfway in its orbit between the solstices. The equinoxes mark two points of balance between the two extremes, when daytime and nighttime are basically equal in length, signaling the beginnings of spring and autumn. Due to the equator crossing through the intersection with the celestial plane, the equinoxes also split the year into halves where each six-month period between equinoxes has longer or shorter lengths of daytime vs nighttime. For example, in the northern hemisphere, we enjoy longer daylight hours and shorter nights from the March equinox up to the September equinox when the days become shorter and nights are longer for the next half of the year. Of course, the southern hemisphere encounters the opposite effects. Even though the tilt of the earth's axis causes us to have some significant fluctuation between the hemispheres and our seasons, there is an amazing equilibrium to the yearly cycle for the entire planet that comes through the equinoxes.
Click on the images below for more details and illustration from timeanddate.com regarding these events:
