This UFO-shaped cloud caused a stir in China when it was spotted hovering in the sky above Jilin Province. The 'lenticular cloud' was pictured moving fast near the Changbai Mountain at the boundary of China and North Korea. After two minutes it was absorbed into a huge cloud cluster and disappeared.
This picture shows what looks like the incredible moment a 'UFO' hovered over Seattle. It was in fact the unusual cloud formations around the iconic Space Needle appearing to reveal an alien ship in the sky above the city. But thanks to the building's saucer-like shape it made for a convincing UFO snap.
A rare occurence in 2008 saw Venus, Jupiter and a crescent moon appear together in the night sky from Portsmouth. While planets have been mistaken for UFOs, experts say the sighting was a 'conjunction'. Robert Massey of the Royal Astronomical Society told the Daily Telegraph that "they just appear close in the sky". He added: "I wouldn't be surprised at all if the... police and the [Ministry of Defense] and the [Royal Air Force] get calls about UFO sightings. Because it's a spectacular sight and quite unusual and I think for that reason people really will be struck by it."
Light bouncing off our camera lenses can cause a flare that shows an otherworldly object in our photos and if well placed they can look like alien spacecrafts, like this lens flare that could be a spaceship following a car.
One of the most mysterious natural phenomena is ball lightning, which is seen as a flash during a storm and is difficult to capture on camera. Scientists have said ball lightning explains many UFO sightings, like when a green object was seen to roll over the mountains over Brisbane, Australia. Astrophysicist Stephen Hughes told the BBC: "If you put together inexplicable atmospheric phenomena, maybe of an electrical nature, with human psychology and the desire to see something - that could explain a lot of these UFO sightings."