Did Nissan 1, 588 BC begin in May rather than April?

Perhaps you are reading this in order to verify the claims of the November 1, 2011 Watchtower. If not, you may wonder, why is this important? The astronomical diary VAT 4956 points to Nebuchadnezzar’s 37th regnal year. By knowing his 37th year, we can calculate back to his 18th year, the year he destroyed Jerusalem.

If Year 37 was 568 BC, Year 18 was 587 BC.

If Year 37 was 588 BC, Year 18 was 607 BC.

According to footnote 17 of the November 2011 article, in the year 588 BC, Nissan 1 (the beginning of the Babylonian year), began on May 2/3, (the day running from the evening of the 2nd until the evening of the 3rd) rather than the conventional date of April 3/4. Footnote 17 claims this is due to the intercalary month in Year 36 that is indicated on line 6 of VAT 4956. Is this true?

First, let us consult what historians have to say. A good resource for the Babylonian calendar is the work Babylonian Chronology 626 BC-AD 75 by Richard A. Parker and Waldo H. Dubberstein.

Here is what they record for 569 to 568 BC:


Note that 569 BC indeed has an intercalary month after the 12th month, just as VAT 4956 indicates in Line 6. They also show that Nissan 1, 568 BC began on April 23rd.

Here is what they record for 589 to 588 BC:


Note that 589 BC did NOT have an intercalary month. Also, they show that 588 BC began on April 4th, not May 3.

In fact, check any credible historical resource and you will find the same thing again and again. The fact is that the month of Nissan NEVER began as late as May in the entire history of the Babylonian calendar. Why? Because the purpose of the intercalary month was to make sure the year did not begin too early. The Babylonians would never have added it in such a way to make the year begin too late. This would have served no purpose.

Note also that VAT 4956 records the summer solstice on the 9th day of the third month:


If in 588 BC, Nissan did begin on May 2/3 and we counted forward to the 9th day of the third month (Sivan), we would arrive at July 8/9. Any astronomical program can tell us what the solstice was on any given year in recorded history. In 588 BC, the solstice was on June 29th—not July 8/9.

In 568 BC, the solstice was on June 29. If we count back from the 9th day of the third month, we find that Nissan 1 begins on April 22/23 as the conventional calender records. One again, VAT 4956 fits 568 BC hand to glove and points to 587 BC as Nebuchadnezzar’s 18th year.

Unfortunately, this means the claim that 588 BC began in May is absolutely false. And without adjusting the Babylonian calendar ahead a month, every claim that is built on it is similarly false.

For more information on VAT 4956 see:

Month 1:


Months 2 & 3:

Side 2:

Or learn to do the archaeoastronomy for yourself:

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