Air traffic controllers have been unable to explain a peculiar aircraft contrail photographed by a member of the public.
The shape of the trail - which turns one way, then quickly back again - suggests the plane it came from made a sudden detour as it flew over Hampshire.
Teacher Florence Lehmann spotted it as she left her home in Southsea at about 7.20am.
Miss Lehmann said: "It's really weird. It looks like the pilot sneezed or fell asleep. Somebody said a UFO had been spotted recently in the area and the pilot had tried to avoid it, which I quite like the sound of.
"There was no wind this morning and the plane actually moved trajectory."
A spokeswoman for Nats, the air traffic control company, said she could not explain why the plane changed direction.
She said: "Unfortunately Nats has no knowledge of the purpose of any given flight and we do not identify individual aircraft to members of the public."
Last week a grey spherical object was photographed in the skies above Portsmouth.
The Met Office reportedly said it was not related to the weather and some believe it was a UFO.