What is this mystery plume of smoke in the sky?
The cloud, which was photographed by Alexia Russell of Newstalk ZB when it appeared yesterday evening over Hobsonville in Auckland, has sparked curiosity on social media.
In a post on Facebook, Ms Russell described the plume as a "strange light".
Others mused the trail could be a "Kim Jong Un missile test" or "aliens".
MetService meteorologist Derek Holland said the plume had most likely been caused by a plane.
"To me it looks like a contrail from an outgoing plane. You can see in the distance two lines of cloud and then after a while it diffuses out and mixes up a bit so you just see this one streak," he said.
"It is just after sunset and the plane is already quite high so it is catching the suns rays."
He said the angle of the cloud had been caused by the wind dragging the cloud.