Amid swirling UFO rumours (to be settled soon), it appears that science may be able to explain at least one sighting. On the evening of 1 May 2006, at least three green fireballs were spotted over Queensland, Australia. At the same time, several observers reported ball lightening—floating luminous balls that are something of a mystery to scientists. No surprise that both have been tied by some to little green men.

Stephen Hughes, a physicist at the Queensland University of Technology in Brisbane, has a different take, though he does think the green fireball and the ball lightening are related. Writing in the Proceedings of the Royal Society A, he claims that the green fireballs were from a meteor or meteors entering the earth’s atmosphere at speeds high enough to ionize oxygen. That ionization, he postulates, created a momentary electrical connection between the ground and the ionosphere which allowed the ball lightning to form. Hughes adds that more far-fetched ideas like mini black holes or antimatter meteors might also be behind it.

Those are marginally better explanations than UFOs, but can they really hold up? My favourite assessment came from University of Canterbury physicist John Abrahamson who told the BBC that Hughes’s ionization theory was “relatively feasible”.

Credit: Proc. Roy. Soc. A