It’s easy to track the phases of the Moon. They’re on just about every printed calendar, plus countless apps and web sites — including ours. That allows you to find the phase on any date far into the future.

People have been devising ways to track the Moon for thousands of years. One of the earliest could be a bone found in Africa. Columns of notches could represent the phases of the Moon.

The Ishango bone was found in present-day Congo, in the remains of a village that was buried by a volcanic eruption. The village was inhabited about 20,000 years ago.

The bone is about four inches long. It’s the leg bone of a baboon, topped by a crystal of quartz. The bone contains three columns of notches. The columns are divided into groups, with each group containing a different number of notches.

The notches could be mathematical. They could represent a counting system, or even serve as a calculator, helping the owner do simple addition or multiplication.

On the other hand, the notches could represent the phases of the Moon. The notches in each group are a different length, so they could represent the waxing and waning of the Moon, covering about six months of phases — an early “calendar” for tracking the Moon.

Tonight, the Moon is about three-quarters full, so it’s nice and bright. And it has a bright companion: Regulus, the heart of the lion. They climb into view in late evening, and soar high overhead later on.

Script by Damond Benningfield

Support McDonald Observatory