IS this a sign of extra-terrestrial life in our midst – or just a smudge on a camera?
Well, it’s an Unidentified Flying Object (UFO) if reports of sightings buzzing around on Twitter are to be believed.
But it is unclear whether the silvery-grey disc-like shape pictured hovering over houses in the above image is in fact a UFO – or a hoax.
It’s baffled several people, including Johnny Blackwell, 23, of Trevor Road, Southsea. He said: ‘I don’t believe in UFOs, but when I saw this I didn’t know what it was.
‘It didn’t look like a cloud, and it was moving very fast.
‘It was a grey, disc-like shape, which I know sounds like a stereotypical UFO, but that’s what it looked like.
‘I don’t know much about military craft, but this was very fast-moving and very odd to see.’
Johnny, a student, said he saw the object at about 7pm on Tuesday.
And Lewis Rogers, 26, of The Seagulls, Lee-on-the-Solent, saw the object when he was visiting a friend in North End.
The animation director said: ‘My initial thought was it was an aeroplane, but it was just moving too quickly.
‘I was the only one that saw it but was quick enough to take the picture.
‘I definitely believe in UFOs and am very interested in science fiction, and often look up at the sky in the evening wondering if there is anything or anyone else out there.’
Some people on Twitter said the UFO is a cloud, but weather experts have dismissed this.
Laura Young, from the Met Office, said: ‘After looking at the images, I can say the object is nothing to do with the weather. It is not meteorological and is not a cloud.’
But before you think little green men will descend upon the city, a space expert does not believe the object is an alien spacecraft.
Karen Masters, senior lecturer in the institute of cosmology and gravitation at The University of Portsmouth, said: ‘Given the pictures show a dark object against a daytime sky, it’s clearly not an astronomical object.
‘Many UFO sightings are the planet Venus, but this one can’t be that.
‘The distances in space are so vast that it’s just not possible for aliens to be visiting Earth, so any interpretation suggesting this is an alien spacecraft is clearly wrong.’
The Ministry of Defence and the Civil Aviation Authority were unable to comment.