Ancient Babylonians Tracked Jupiter Using Geometry

Posted on February 1, 2016

Ancient Babylonian tablet showing geometry use in tracking Jupiter

Researchers have discovered five Babylonian tablets that indicate the ancient Babylonians used geometry to track the planet Jupiter. The discovery pushes back the use of this type of geometry but at least 1,400 years. The cuneiform tablets are from 350 to 50 BCE.

One of the tablets showing the use of geometry is pictured above. The researchers say the ancient astronomers calculated Jupiter's position using the area under a time-velocity graph. The tablets depict two intervals from when Jupiter first appears along the horizon. Jupiter's position is calculated at 60 and 120 days.

The texts contain geometrical calculations based on a trapezoid's area and its long and short sides. The Babylonian astronomers also computed the time when Jupiter covers half of the 60-day distance by partitioning the trapezoid into two smaller ones of equal area. It was previously thought that Babylonian astronomers operated exclusively with arithmetical concepts.

Tracking Jupiter was important to the ancient culture because of a strong belief in sky and Earth connections. Professor Mathieu Ossendrijver, author of the paper from Humboldt University in Germany, told Scientific American, "It was thought that if you are able to predict the motion of Jupiter, you would also be able to predict the price of grain, the weather, the level of the river Euphrates."

The discovery of the tablets raises more questions about just how advanced the ancient culture was. The exact origins of geometry in Babylonia are still unknown. It is also unknown how prevalent the use of geometry was during the time period.

Ossendrijver also told BBC News, "It could be that there was an earlier tablet, written by a genius, by one individual, who came up with this new way of doing astronomy. It could also be that in fact this is a method that was more widely applied by different scholars. We don't know."

Ancient Babylonian tablet and trapezoid graph showing use of geometry in ancient Babylonia


A research paper on the findings was published here in the journal, Science.

Photos: Trustees of the British Museum/Mathieu Ossendrijver