Melbourne Weather Phenomenon (2 in a series)

As a child I was fascinated by the stories of UFOs in Erich von Daniken's Chariots of the Gods series of books. Well, there's my first sighting on the horizon of this photo, taken returning home from Thoughtworks' Quarterly Technology Briefing in Sydney.

Sadly, too many easy explanations I suppose. Gas balls escaping from a federal carbon trading policy perhaps...