The oldest known meteorite strike on Earth happened 3.5 billion years ago in a place that today is the red, rocky Pilbara region of Western Australia. Scientists say they have found the “smoking gun” evidence: tiny droplets of rock that were vaporized on impact and then solidified into spherical grains called spherules.
A 3.5 billion year old crater, preserved in ancient rock
The discovery was made in the Pilbara, a remote area in northwestern Australia that holds some of the planet’s oldest exposed rocks. Researchers from Curtin University and the Geological Survey of Western Australia examined a layer of sedimentary rock known as the Antarctic Creek Member. Within it, they found spherules less than a millimeter wide. These tiny glassy beads form only when a meteorite slams into Earth with enough force to melt and spray rock into the sky. The chemical makeup of the spherules matched extraterrestrial material, confirming the impact.
Why this matters to the people who live there
The Pilbara is not just a scientific treasure. It is also home to Indigenous communities and a major mining hub for iron ore. For local geologists and traditional owners, the region’s ancient landscapes have long hinted at a violent past. This finding gives them a precise date for one of the earliest known cosmic collisions. The impact would have been catastrophic, vaporizing rock and throwing debris across hundreds of kilometers. But it also may have helped shape the early Earth’s crust and atmosphere, conditions that eventually allowed life to emerge.
The discovery pushes back the known record of meteorite impacts by more than a billion years. The previous oldest confirmed strike was in South Africa, dated to about 2.2 billion years ago. The Pilbara impact occurred during the Archean eon, when Earth was still young, its surface hot and largely ocean covered. The meteorite itself was likely a large asteroid, though its exact size remains unknown.
This finding does not rewrite history so much as extend it. It shows that Earth was being bombarded by space rocks far earlier than scientists had solid proof for. And it confirms that the Pilbara, already famous for its ancient fossils and rock art, holds a record of planetary violence that predates almost everything else on the planet.
