The Min Min light is one of the few genuine anomalies that comes with a folk warning attached: don't chase it. For more than a century, drovers, stockmen and motorists in the Channel Country of western Queensland have reported a glowing ball, roughly a quarter the size of the full Moon with soft, restless edges, that hovers near the horizon, follows a moving car or rider, keeps its distance no matter how fast you go, and then simply winks out. The Aboriginal communities of the region knew it; the settlers named it after the long-gone Min Min Hotel. It is as well-attested an 'spirit light' as exists anywhere on Earth.

What makes Min Min a serious case rather than a campfire story is that the reports are consistent, multi-witness, and span generations and cultures. People who have never met describe the same behaviour: the light recedes as you approach, paces you, changes colour, and can appear to be 'right there' on the track ahead while remaining forever unreachable. That consistency is the kind of thing that usually signals a real physical cause rather than mass imagination, and that is exactly what makes the conventional 'ghost' framing so tempting and so wrong.

The man who took it apart was John Pettigrew, a neuroscientist and polymath at the University of Queensland, and crucially he didn't theorise from an armchair. He went to the outback and ran a field experiment. Pettigrew had a companion stationed at a remote campsite, then drove roughly 10 kilometres away, below the horizon from the camp's point of view, and switched his car headlights on. Over the radio, the people at the camp reported exactly the classic Min Min: a bobbing light just above the horizon, about half the size of the full Moon, shifting through red, orange, yellow and green. When Pettigrew flicked his headlights off, the 'Min Min' vanished; when he switched them back on, it returned. He had a light he could turn on and off from kilometres beyond the visible edge of the world.

The mechanism is an inverted mirage called a Fata Morgana. On clear outback nights the ground radiates heat away and a layer of cold, dense air settles near the surface with warmer air above it, the reverse of the daytime gradient that produces shimmering road mirages. This temperature inversion can act as an atmospheric optical duct, bending light from a source far over the geometric horizon and channelling it to a distant observer, where it arrives compressed, magnified, shimmering, and apparently floating near the horizon. A campfire, a truck, or a car beyond the curve of the Earth becomes a hovering orb. Pettigrew published the full optical account in the journal Clinical and Experimental Optometry in 2003, arguing that some historic Min Min sightings could trace to sources hundreds of kilometres away, well before headlights existed, when the 'source' might have been a distant campfire.

This is, by the standards of the unexplained, a model solution, and intellectual honesty means saying so. Pettigrew didn't wave his hands at 'atmospheric conditions'; he made a falsifiable prediction, went into the field, and produced the phenomenon on demand from a known source, then backed it with the physics in a peer-reviewed paper. The 'follows your car' behaviour falls out naturally, because the inversion duct moves with the observer's line of sight, the apparent light tracks the viewer rather than chasing them. The receding-on-approach behaviour falls out too, because as you move, the geometry that bends a faraway source toward your eye keeps shifting. The Fata Morgana account explains the whole catalogue of weird behaviours without invoking anything supernatural.

Where it gets less tidy, and where Inverted World won't pretend otherwise, is that 'we proved one specific Min Min was headlights' is not the same as 'every Min Min ever reported was a mirage.' The Fata Morgana requires the right inversion, the right viewing geometry, and a real light source somewhere over the horizon, and not every historical sighting comes with a candidate source we can point to. Some accounts describe lights that approach very close, or behave in ways a strict optical-duct model strains to cover, and the outback is also home to ball-lightning reports, bioluminescence, and plain misidentification. The mirage almost certainly accounts for the core of the phenomenon. It does not obviously account for every outlier.

So the Min Min ends in a rare and slightly uncomfortable place for a 'spirit light': mostly solved. Pettigrew handed us a repeatable experiment and a mechanism that survives peer review, which is more than 99 percent of the world's anomalous lights can say. The honest residue is the long tail, the handful of historic sightings with no traceable source and no convenient inversion, which the mirage explains in principle but can't confirm in fact. The ghost light of the outback turned out to be light. The open question is only how far away, and from what, the very oldest of those lights were really shining.