Massing of the planets

The massing of the planets recorded on 25 March 185 BCE is one of the clearest examples of how advanced Babylonian astronomical observation had become by the Hellenistic period. This event is preserved in two independent cuneiform sources: Astronomical Diary BM 32562 and Astronomical Diary BM 46051.

By the 2nd century BCE, Babylonian astronomers had already developped predictive schemes for planetary motion and made a clear separation between observation and interpretation and observations where not mythological or symbolic anymore.

It serves a bridge between naked-eye astronomy and later mathematical models.