The Sumerian star map known as the Planisphere may preserve a record of an unusual night sky, but it does not provide a simple, proven account of an asteroid strike. The tablet is fascinating precisely because the astronomy, the cuneiform text, and the later interpretation do not line up perfectly.
Known as “the Planisphere,” the ancient cuneiform tablet has puzzled historians and astronomers for over a century. It was unearthed in the 19th century during excavations at the ruins of Nineveh in modern-day Iraq, and today it’s housed in the British Museum under the catalog number K8538. For decades, no one could make full sense of it—until modern astronomy software gave researchers a way to reconstruct the night sky as it looked thousands of years ago.
The proposed connection to the Köfels landslide in Austria comes from a modern reading of the tablet, not from a surviving Sumerian sentence that names the crater. Compare this case with Curiosmos coverage of the oldest Sumerian flood tablet: in both stories, the value lies in separating what the object records from what later readers want it to mean.
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That’s when the clues started lining up.
A cosmic event recorded in clay
The surviving tablet was made by an Assyrian scribe around 700 BCE, according to the University of Bristol’s 2008 account. Alan Bond and Mark Hempsell proposed that it copied a much earlier observation, which they dated to 29 June 3123 BCE. The age of the surviving object and the date proposed in their interpretation are different things. The tablet contains celestial data, constellations, and markings of planetary positions. But it also describes something far more dramatic.
In one section, the observer refers to a strange object appearing in the sky—a glowing, fast-moving body he calls a “white stone bowl.” According to researchers, this could be a description of a massive asteroid entering Earth’s atmosphere.
By using astronomical modeling software, scientists were able to align the tablet’s observations with the night sky over Mesopotamia on a specific date: June 29, 3123 BCE.
What they found was staggering: the trajectory described by the Sumerian astronomer appears to match the path of an asteroid believed to have caused the destruction of Köfels in Austria—an event that left no visible crater, but signs of intense geological upheaval.
How a Sumerian star map led to Köfels
Roughly half of the Planisphere tablet is dedicated to charting the position of stars and planets. The other half, however, focuses on an extraordinary event—something so unusual that the observer carefully noted its movement across the sky, relative to known constellations.
In Bond and Hempsell’s reconstruction, the object was an Aten-type asteroid, at least one kilometer wide. These types of asteroids follow orbits that bring them very close to Earth.
What made the Köfels event unusual is the lack of a clear impact crater. But the data from the Sumerian star map may explain why.
According to the analysis, the asteroid entered Earth’s atmosphere at a very low angle—around six degrees. This shallow trajectory likely caused the asteroid to clip a mountaintop—possibly Gamskogel—before disintegrating in the air.
As it tore through the valley near Köfels, the asteroid became a massive fireball approximately five kilometers in diameter, generating extreme pressure that pulverized rock and leveled terrain. But because it was no longer a solid object by the time it hit the surface, no traditional impact crater was left behind.
What does the geological clock show?
A separate line of evidence comes from the landslide itself. A 2015 study by Kurt Nicolussi and colleagues combined tree-ring analysis with six radiocarbon samples and dated the Köfels landslide to 9527–9498 calibrated years before present, roughly 7,600 BCE. That is more than four millennia earlier than the 3123 BCE event proposed in the tablet interpretation. The two dates do not describe the same event unless that discrepancy can be resolved.
Ancient knowledge hidden in plain sight
The idea that a Sumerian star map could document such a precise astronomical event thousands of years ago might seem far-fetched—and Bond and Hempsell reported that their reading of its trajectory agreed to within one degree with their calculated trajectory.
That is the possibility their interpretation raises: could a later clay tablet preserve an account of a much older event? The proposed trajectory is part of their reconstruction, rather than independent confirmation that the impact occurred.
The tablet’s astronomical markings make it a compelling object in their own right. Establishing the proposed connection with Köfels requires evidence about both the text and the geological event; a modelled match alone cannot settle that connection.
