Venus Tablets of Ammizaduga

These tablets give the years, months, and day numbers on which Venus reached positions labelled EL, MF, ML, and EF over a period of twenty-one years. The sequence of phenomena repeated itself every ninety-nine Babylonian months less four days.

On the tablets, it is noted that periods of invisibility are always three months or seven days. Also, the dates are grouped in sets involving equal increments from set to set. Thus, the Babylonians were aware of the periodicity of the phenomena.

The exact dates of the tablets are not known. However, the reign of Ammizaduga has been set at 1582-1562 BCE.