Using modern techniques Brad Schaefer, an astronomer at Louisiana State University, is reported in Nature as having dated ancient observations on a set of ancient clay tablets that display constellations thought to be precursors of the present-day zodiac to 1,370 BC.
The tablets, known collectively as MUL.APIN, contain nearly 200 astronomical observations, including measurements related to several constellations. They are written in cuneiform, a Middle-Eastern script that is one of the oldest known forms of writing, and were made in Babylon around 687 BC.
But most archaeologists believe that the tablets are transcriptions of much earlier observations made by Assyrian astronomers. Just how much older has been disputed, with estimates going back to 2,300 BC.
He also worked out that the ancient observers lived within roughly 100 kilometres of 35.1° N — an area that includes the ancient Assyrian cities of Ninova and Asur. The results were presented at the American Astronomical Society's summer meeting in Honolulu, Hawaii.