Because Woodleigh never breaks the surface, its true size remains genuinely uncertain, and that uncertainty has fuelled decades of scientific argument. The team that announced it in 2000 argued it might stretch up to 120 kilometres across. If that larger estimate holds, Woodleigh would rank among the four largest confirmed impact structures on the planet, the kind of wound that implies a bolide several kilometres wide. A later study in 2003 was more conservative, suggesting something closer to 60 kilometres. Either way the scale is staggering: a buried central uplift roughly 20 kilometres in diameter sits at its heart, the rebound of crust that recoiled like struck water and froze mid-splash. That central peak is the signature of a truly enormous impact, the place where the deep rock bounced back after the strike. The argument over the crater's width is itself a measure of how violent the event must have been.

Drilling first punched into that central uplift in the late 1970s, but no one understood what they had hit. The rock looked odd; the meaning did not land. Not until a 1997 gravity survey, which revealed a strange circular anomaly buried in the Carnarvon Basin, did the suspicion of an impact take hold. A team of four scientists from the Geological Survey of Western Australia and the Australian National University, led by Arthur J. Mory, made it official, announcing the discovery in the 15 April 2000 issue of Earth and Planetary Science Letters. A crater that had waited out the entire age of the dinosaurs, undetected, was finally named.

The clinching evidence came nearly two decades later. In 2018, researchers found reidite in a Woodleigh drill core, the first time the mineral had ever been identified in Australia and only around the sixth time anywhere on Earth. Reidite forms from ordinary zircon only under the colossal shock pressure of a major impact; it is, in effect, a fingerprint of cosmic violence. Its presence strengthened the case that Woodleigh's crater was once well over 100 kilometres wide, possibly the largest in the country. To hold a fleck of reidite is to hold proof of a moment of almost incomprehensible force, preserved in stone.

For years the impact was thought to be relatively young, somewhere between the Late Permian and Late Triassic. Newer dating pushes it far deeper into the past, to roughly 364 million years ago in the Late Devonian. That timing is provocative, because it falls close to the Late Devonian extinction, one of the great die-offs in the history of life, when much of the world's marine ecosystems collapsed over a span of geological time. Woodleigh was not alone in that era. Other large impacts, such as the buried East Warburton Basin in central Australia, may date from around the same window. If asteroids helped drive that extinction, more than one may have struck a reeling planet, a salvo rather than a single blow. Of the two dozen-plus impact structures known in Australia, the three largest are Woodleigh, Acraman, and Tookoonooka, a buried trinity of ancient catastrophe written into the continent's bones.