Egyptian star chart and decanal clock, from the ceiling of Senenmut's tomb, c. 1473 BC

The figures represent constellations or protective deities, and the columns of text in the upper part list planets and stars known as the decans. The twelve circles in the lower part, each divided into twenty-four segments for the hours of the day and night, are labelled with the names of the months of the year.

The Celestial Diagram consisted of a northern and a southern panel which depicted circumpolar constellations in the form of discs; each divided into 24 sections suggesting a 24-hour time period, lunar cycles, and sacred deities of Egypt.

The map on the southern panel could well reflect a specific conjunction of planets in 1534 BCE around the longitude of Sirius. The four planets Jupiter, Saturn, Mercury and Venus are relatively easily recognizable. The planet Mars is not included in the actual grouping and at first sight seems to be missing in the map. However, one explanation is that Mars is represented in the Senenmut map as an empty boat in the west. This may refer to the fact that Mars was retrograde and was not with the other planets (indeed, being in the west in the 1534 BCE conjunction). The reason for the boat being empty is perhaps in this backward movement (a well known phenomenon to the Egyptians) the position of Mars was not considered to be ”concrete”.