(Investigator 97, 2004 July)

Min-min lights are mysterious lights in Australia’s Outback which appear suddenly, may chase you if you're in a car, approach rapidly to within a few metres, often switch position dramatically, and have no discernible origin.

"Min-min" is an Aboriginal term and was also the name of a remote Outback hotel – burned down long ago – in north-west Queensland.

Investigator readers were introduced to the "min-min light" mystery in Number 6 (1989 May). Some min-min occurrences may be the explanation for supposed flying-saucer sightings.

Jack Pettigrew of the University of Queensland has now removed some of the mystery.

In one night-time experiment he drove a truck 10km from where he and companions were camping, parked at the bottom of a water-course, pointed the truck toward the camp, and switched the lights on and off while maintaining radio contact. His companions in the camp saw the min-min come and go in synchrony with the truck lights going on and off.

The min-min is a mirage that occurs when a layer of warm air lies above a layer of colder air near ground level. The cold layer traps lights by refraction and may channel it over long distances. During day-time people easily estimate distance using their binocular vision and reference points like mountains, trees, etc. At night such estimation is difficult and therefore, if a light is seen, people rely more on brightness cues. A light that's getting brighter may then be interpreted as getting closer or even as chasing the observer.

In January 1988 the Knowles family made national headlines after being chased by a UFO on the Nullarbor Plain. What they saw may have been the "min-min". (Investigator 11)