A group of boys reported seeing an unidentified object over North Salem, Oregon.

Photographer Miguel Tohme took this photo of a flying object when he saw a white dot on the sky which moved around and was changing color form white to red, green and yellow, in Bahia Blanca, Argentina, 15 July 1965. He made several pictures of the object, but the negatives showed two lumious spots.

A UFO seen over London in 1978.

This photo provided by NASA shows an unidentified possible small debris recorded with a digital still camera by astronaut Daniel Burbank onboard the space shuttle Atlantis in September 2006.  Engineers do not believe this to be the same object seen in video taken by shuttle TV cameras earlier in the day.

This image made from video shows unidentified flying objects in the skies over southern Campeche state filmed by Mexican Air Force pilots on 5 March 2004, according to a Defence Department spokesman. A series of brightly lit, rapidly moving objects filmed in the skies over Mexico could have been caused by a scientific phenomenon involving gases in the atmosphere, a scientist said.

An unidentified flying object over the town Cluj in Romania in September 1968.

This photograph, reproduced from the quarterly UFO periodical Flying Saucers International in Los Angeles, shows silvery white flying objects as seen by photographer Erich Kaiser while descending from Reichenstein mountain in Austria on 3 August 1954.

The Ministry of Defence has released documents for the first time that details the hundreds of sightings of Unidentified Flying Objects (UFOs) in the UK between 1978 and 2002.

Sketches were made based on the detailed descriptions people gave of flying saucers they claim to have spotted in both urban areas as well as rural - including central London.

Explanations were found for may of the sightings, including one near Gatwick which turned out to be nothing more harmless than the lights from the airport. 

Sketch of a 'flying saucer' described by police officers from Edgware police station, in London sent to the MoD by their Superintendent.

The authorities did take sightings seriously and those reported were documented. But there were also theories that some could be spy equipment being used by alien nations rather than aliens from another planet.