18. An Ancient Observation

A typical Diary inscription names a celestial body, notes its position, and gives the (Babylonian) date of the observation and an indication of the time.

Diary No. -567 reads: Line 8: Month II, the 1st (of which the 30th of the preceding month), the moon became visible while the sun stood there, 4 cubits below fl Geminorum; it was thick;

The observation was made the first day of Month 2, when the crescent of the moon first became visible near the western horizon at sunset. The moon was close to the normal star beta Geminorum. The lunar crescent was thicker than a sliver, and it was visible while the sun stood there above the horizon.