Egypt leaves Mars an empty boat
On the painted ceiling of Senenmut's tomb at Thebes, four planets ride their sacred boats and a fifth boat sails empty. The empty one is probably Mars.
In an unfinished chamber cut into the rock at Deir el-Bahri, below Hatshepsut's terrace temple, painters covered a ceiling with the oldest star map surviving from Egypt. The tomb is TT 353, cut for Senenmut — the queen's chief architect and high steward — in the 1470s BCE. The southern panel carries the decan stars, Orion and Sirius, and a row of planets riding in boats the way gods should ride. Four are recognisable: Jupiter, Saturn, Mercury, Venus. The fifth boat, off in the west, has nobody in it.
That empty boat is the usual reading for Mars. The Egyptians knew the planet well enough to name it twice: Her Desher, "the red one," and Horus of the Horizon. They also knew it did something the fixed stars never do — Egyptian sources record the red Horus travelling backwards, retrograde motion noted without explanation. The suggestion is that a planet caught moving the wrong way had no settled place in the grouping, so the artist gave it a boat and left the seat empty.
This is an interpretation, and it is contested. The panel appears to show a particular gathering of planets near the longitude of Sirius, and the Egyptologists who worked out which sky that was dated it to 1534 BCE. Hatshepsut is conventionally dated to 1479–1458 BCE, which puts the conjunction decades before Senenmut could have watched it. Either the ceiling records a sky nobody in that tomb ever saw, or the Egyptian chronology is wrong by half a century, or the arrangement is decorative and the whole reading collapses. Nobody has settled it.
What Egypt did not produce is numbers. Egyptian astronomy was formidable at the jobs it was built for — decan clocks that divided the night into twelve hours, a 365-day civil calendar, pyramid faces set close to true north, at least forty-three constellations recognised by the thirteenth century BCE. But there are no tables of Mars's positions, no attempt to say where it would be next year. The planets stayed gods in boats. Turning Mars into arithmetic took a different civilisation, eight centuries later and nine hundred miles to the east.
The name outlasted the language. On modern Mars, a channel running through Noachis Terra is called Her Desher Vallis, approved by the International Astronomical Union and photographed in 2020 by the THEMIS camera on NASA's Mars Odyssey orbiter. Three and a half thousand years after a painter in Thebes left a boat empty, the word Egyptians used for the red one is an address on the surface.