27 March 2003

A UQ neuroscientist has revealed the probable basis of a bizarre Australian Outback phenomenon that has baffled observers and scientists for centuries.

The western Queensland town of Boulia has built its tourist reputation on Min Min lights, mysterious lights that seem to follow travellers for long distances.

Professor Jack Pettigrew said despite intense interest in the Min Min, they had never been explained in a satisfactory way.

“The Min Min light seems to have magical qualities, sometimes following observers, even as they speed away in vehicles, while at other times seeming to retreat shyly,” he said.

Professor Pettigrew, who is the Director of UQ’s Vision, Touch and Hearing Research Centre, provides an optical explanation and data about Min Min lights in the current edition of Clinical and Experimental Optometry, the journal of the Optometrists Association of Australia.

He used his skills in the vision sciences combined with extensive first-hand experience of the Diamantina region of Western Queensland at night. Professor Pettigrew was studying an elusive nocturnal bird, the letter-winged kite in the region, where he encountered the phenomenon.

“The Min Min light occurs when light, from a natural or man-made source, is refracted to an observer who is tens, or even hundreds, of kilometres away, by an inverted mirage, or Fata Morgana,” he said.

“Named after the Morgan fairy, who was reputed to be able to conjure cities on the surface of the sea ice, the Fata Morgana has a real physical phenomenon, being caused by a temperature inversion.

“A cold, dense layer of air next to the ground (or sea, or sea ice) carries light far over the horizon to a distant observer without the usual dissipation and radiation, to produce a vivid mirage that baffles and enchants because of its unfamiliar optical properties.

“In a celebrated and authenticated example, the Irish sea cliffs were seen floating in vivid greens and browns above the calm Atlantic by observers on a ship more than a thousand kilometres away.

“Wonderful during the day, such Fata Morgana can be terrifying at night when a single light source gives no hint that it is actually part of a mirage emanating from a great distance. Even hardened Outback observers can break down when they are unable to interpret the unusual optical properties of the light in terms of their own, very different, past experiences.

“The unusual terrain of the Channel Country makes the favourable atmospheric conditions more likely, while its isolation increase the impact of a single light source since the observer knows that it cannot be produced locally but sees it apparently there in front.”

Professor Pettigrew said some people would prefer not to have the Min Min’s mystique probed by city slickers.

“I apologise to them. However, knowing more about the unusual weather conditions responsible, could improve one’s chances of seeing it,” he said.

“Increased knowledge has certainly not lessened my own wonderment at the phenomenon on those infrequent occasions I’ve witnessed it.”

Media: Further information (after 10am):
Professor Jack Pettigrew, telephone (work) 07 3365 3842 email: j.pettigrew@vthrc.uq.edu.au

A link to the article can be reached from Professor Pettigrew’s web site http://www.uq.edu.au/nuq/jack/jack.html