The Otago Daily Times could be forgiven for imagining the latter, because when it went delving for answers to the mystery of the cloud-like formation, pictures of which were published in yesterday's ODT, it was told by Airways New Zealand, the national air traffic control organisation, that it would have to file an Official Information Act request and wait up to 20 days for answers.
Thankfully, ODT readers were more forthcoming, with phone calls coming in from between Waikouaiti and Milton.
Suggestions on the trail's origins ranged from jet flights to or from South America, to Antarctic military flights.
However, an Airways spokeswoman said as it was not a flight controlled by Dunedin air tower, the information could not be released without an Official Information Act request (OIA).
Late yesterday, MetService meteorologist Ross Marsden was able to solve the puzzle.
It was, he reliably informed the ODT, the vapour trail - or contrail - of a United States Air Force C17 flight from Christchurch to McMurdo Station in the Antarctic.
So now we know - and the sky has not fallen.
