Will the Real Equinox Please Stand Up

Source: Will the Real Equinox Please Stand Up (Nehemia Gordon)

Last week we found Aviv barley in the Land of Israel and the new moon on Wednesday night was the New Moon of the Aviv marking the beginning of the Biblical year. I discuss the biblical evidence for the role of the Aviv barley in the Biblical calendar at:

http://www.karaite-korner.org/abib.shtml

Some people object that the true indicator for the beginning of the Biblical year should not be the Aviv barley but the Vernal Equinox, the day which marks the beginning of Spring. They base this on an anachronism in their interpretation of the biblical Hebrew word Tekufah ("circuit"). An anachronism is erroneously placing something from a later time period into an earlier one. For example, speaking about telephones in ancient Rome is an anachronism. Interpreting the Biblical Hebrew word "Tekufah" as meaning "equinox", a meaning it never had in Tanakh times, is an anachronism. I won't go into too much detail here about the word Tekufah as I have done so in the past. For more information on this topic please see:

http://www.karaite-korner.org/abib_faq.shtml
http://www.karaite-korner.org/abib_and_tekufah.shtml
http://groups.yahoo.com/group/karaite_korner_news/message/220
http://groups.yahoo.com/group/karaite_korner_news/message/124

Today I want to point out another anachronism in the application of the vernal equinox by those who claim it has a role in the Biblical calendar. Specifically I want to ask the question: If we are really required to use the vernal equinox for the biblical calendar, then which equinox? The problem is that there was no reliable way to calculate the timing of the Vernal Equinox in antiquity. Today modern astronomers have worked out with a high degree of accuracy the exact timing of the Vernal Equinox. The prerequisite for determining the true equinox was discovering the exact length of the solar year. According to modern astronomers a solar year is 365 days 5 hours 48 minutes 46 seconds and this year the equinox falls out on March 21, 2010. Easy, right? Not so fast. The true value of the solar year was not known until modern times.

Fear not, say advocates of the equinox, Moses had secret astronomical knowledge learned at the court of Pharoah. This secret knowledge supposedly included the exact calculation to work out the true timing of the Vernal Equinox. If Moses had this secret knowledge it was unfortunately unknown to later Jews. The early Rabbis mention the Vernal Equinox but they did not have a way of reliably calculating it because they did not know the true length of the solar year. There were actually two contradictory opinions about the length of the solar year and both were wrong. According to Rabbi Samuel the solar year was 365 days 6 hours whereas Rabbi Ada reckoned the solar year to be 365 days 5 hours 55 minutes 25.4 seconds. The difference between these two values may sound trivial but they result in the Vernal Equinox falling out on different days, neither of which is the correct day! For example, this year the Equinox of Samuel falls out on April 8, 2010 whereas the Equinox of Ada is March 28, 2010. As already mentioned, the true Vernal Equinox is March 21, 2010 - 7 days before the Equinox of Ada and 18 days before the Equinox of Samuel. Which one of these three values did Moses supposedly use: the Equinox of Ada, the Equinox of Samuel, or the true astronomical value only worked out in modern times? If this knowledge was known to Moses then why was it unknown to every other ancient civilization including the Jews? Did God really intend for us to wait for the advent of modern astronomy to know the true timing of the biblical feasts? Or did he set out a simple system that ancient Israelite farmers could easily follow by looking at their crops as they grew in the fields? It seems to me this is what the Creator was talking about when he said: "Observe the Month of the Aviv" in Deuteronomy 16:1. No need for secret astronomical knowledge; just a simple way to track the solar cycle relevant to an ancient farming society.

As a side note, the Vernal Equinox is generally calculated today as a moment in time not as a day. This year the Vernal Equinox was March 20 at 7:32pm Israel time. In the Hebrew reckoning, the day begins at sunset and this was well after sunset presumably making March 21 the day of the Vernal Equinox. But not so fast with this either! The ancients defined the equinox as the day on which daytime and nighttime were of equal length as we can see from the following quotation from the Jerusalem Talmud (Berachot 2c 1:1): "On both the Vernal Equinox and Autumnal Equinox the day and the night are equal". So when would that be for observers in the Land of Israel, March 20 or 21 this year? Considering that they did not have accurate clocks in ancient times, this would be no small feat to figure out, which is why both Samuel and Ada got it wrong. If you look at TimeAndDate.com for the day on which the daytime and nighttime are equal in Jerusalem you get a surprising result: March 16 or 17! On March 16 there was 11h 59m 12s of daytime and on March 17 there was 12h 01m 09s. So is the "Biblical" equinox March 16 or 17 based on day lengths in Jerusalem? Or March 21 as if Moses lived at the equator? Or March 28 or April 8 based on the ancient values of the year?
Check the Jerusalem day lengths in March 2010 for yourself:
http://www.timeanddate.com/worldclock/astronomy.html?n=110&month=3&year=2010&obj=sun&afl=-11&day=1

Nehemia Gordon
Jerusalem, Israel