According to a Babylonian astronomy observation text, there was a lunar eclipse in Nebuchadnezzar's 32nd year. This eclipse has been placed at 568 BC.

I'm assuming we can then affirm that Nebuchadnezzar was made King in 605 BC due to the information in this event. However, I'm aware that the Babylonians used a lunar 354.37 day year. It was only until about 500 BC that they began introducing the metonic cycle which would've made their calendar more fitting to the solar year.

If I'm correct, wouldn't have Nebuchadnezzar's 32nd 354.37 year been different to a 32nd 365.242 year?

And again, if this is right, wouldn't have Nebuchadnezzar been made King in a different year other than 605 BC?

  • 2
    Citations would improve this question.
    – MCW
    Sep 5, 2017 at 9:21

3 Answers 3


Nabu-kudurri-usur (Nebuchadnezzar II), was the oldest son of Nabu-apla-usur (Nabopolassar), founder of the 11th dynasty of Babylon. From the records, we know that he was born c634BC and died c562BC (aged 71/72). He succeeded his father to become king c605BC. (the "c" in all these dates stands for "circa" or "about")

You are right that we use a number of astronomical events to provide fixed points that we can use to tie the various near eastern chronologies together. A well known one is the "Assyrian eclipse" of 15 June 763BC (although even that date is not without controversy!). As I understand it, and as you say in your question, the "saros" texts record another solar eclipse in the 32nd year of Nebuchadnzzar's reign. Now, I think that has been suggested to be an eclipse in either 573/572BC, which would correspond to Nebuchadnezzar II becoming King of Babylon c 605BC.

Now, you're quite right that, as with many other ancient calendar systems, the Babylonians faced a challenge of making their calendar of twelve lunar months fit with the solar year of about 365.25 days. This has added a further complication to matching events recorded in Babylonian records to exact dates in our modern calendar. A bigger complication is that most events aren't actually recorded with a date, just a regnal year - e.g.

"In the 32nd year of the reign of King Nabu-kudurri-usur ..."

This is why dates are usually given as circa ...; When I see a text that says something like

"Nebuchadnezzar II became King c605BC",

I read it as

"Nebuchadnezzar II became King in 605BC, give-or-take a year or so".

So, yes, Nebuchadnezzar II could well have become King in a different year from 605BC, but 605BC is our best guess; and writing the date as c605BC makes it clear that we are not certain that the event actually happened in 605BC.

  • 1
    Thank you very much. It seems to make sense that Nebuchadnezzar II 37th year in 568 BC would fit his ascension year as 605 BC ONLY on the knowledge that the Babylonian calendar fitted in 7 extra months every 19 years to make their calendar more fitting to the solar year. It's just that my sources told me that they didn't do this properly until around 500 BC. Your link, however, has let me know that they did do this before 500 BC but more informally. Thank you very much.
    – user329957
    Jun 15, 2017 at 12:55

I think you mean Nebuchadnezzar's 37th year. Eugene Faulstich has addressed and concludes it should be 569 BCE. Correction Veadar 569,not 568 BCE

See also Faulstich essay Seleucid Astronomical Tablets


You are misinformed about the Babylonian calendar. From the very earliest times the Babylonians had a luni-solar calendar with 12 months in a common year and 13 in an intercalated year. In the early periods intercalation was based on ad-hoc astronomical observation. The Metonic cycle gave a mathematical formula for determining the intercalated years, but intercalation is much older.

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