Ancient Babylonians used geometry to track planets

Ancient Babylonian astronomers were the first to use geometry to calculate the movement of planets through space, a new study suggests.

It was previously thought that this type of analysis had only originated hundreds of years later, in 14^th century Europe.

The report, written by Professor Mathieu Ossendrijver at Humboldt University in Berlin and published this week in Science, analysed mathematical data on four ancient Babylonian tablets, dating back to between 350 and 50 BCE.  

The tablets describe Jupiter’s velocity by recording its position in relation to time.

One tablet shows daily records of Jupiter’s position taken over a 60-day period. The data then use a time-velocity graph and mathematical algorithms to demonstrate Jupiter’s movement, recording the area of the trapezoid that would be created by the time-velocity graph. 

'The Babylonian supreme god was Marduk, his planet was Jupiter'

The trapezoidal figure itself is not shown on the tablets, but Ossendrijver’s research suggests geometry is being used.

“I would like to think that the Babylonian scholars did make drawings of the trapezoid figures and that by coincidence we have not found these tablets with the drawings,” he told Cosmos.

The focus on Jupiter, and this particular 60-day interval, remains a mystery, but Ossendrijver has his theories. “The Babylonian supreme god was Marduk, his planet was Jupiter,” he explains.

“The tablets most likely originate from Babylon and were written by astronomers employed by its main temple. This may not be a coincidence.”

Until now, the first use of geometry to track planetary movement was attributed to 14^th century European astronomers – around 1,400 years after these tablets were created. This research suggests ancient Babylonians significantly influenced the use of geometry in western astronomy.

Written in cuneiform script, the artefacts form part of a series of around 450 tablets relating to astronomy found in Babylon and Uruk, from the period 400 to 50 BCE.  

Most of the tablets in this series depict tables of lunar and planetary data, while others use further detail to verify the tables.

Ancient Greek astronomers also used geometrical methods, says Ossendrijver, but they were describing configurations in physical space, rather than in abstract mathematical space, defined by time and velocity.