Today, the National Archives released their tenth, and final, bundle of files from the Ministry of Defence’s (MoD) UFO desk, which closed back in 2009.
Rather than uncovering an extra-terrestrial conspiracy, the last batch of files reveal that at the time of the closure the MoD had “no opinion” on the existence of extra-terrestrial beings, and seemed a little fed up by the hundreds of reported UFO sightings that they were recieving each year.
So, the next time you see something in the sky, consider the following possibilities before donning your tinfoil hat.
Top secret spyplanes like the Blackbird (Lockheed SR-71) were often taken to be UFOs during the Cold War.
In recent years, the triangular-shaped stealth fighter (F-117A Nighthawk) and bomber probably have been, too.
Who knows how many new sightings are down to top-secret craft we don’t even know about – perhaps even saucer-shaped ones?
A yellow-ish object appears out of nowhere, flying fast and silent across the sky and leaving a glowing trail behind it.
The object suddenly breaks into smaller pieces before vanishing into thin air – all in under a minute.
Over-anxious witnesses might run screaming to the media, but astronomers will be content to have seen a spectacular meteor fireball.
If you’ve been observing for a long time you’ll be all too aware that light sometimes bounces off the lens elements in your camera, binoculars or telescope, causing a lens flare.
Some flares can look like solid objects and, if they’re accidentally framed in the right place, a newbie might well mistake them for an unworldly spacecraft.
Sometimes all rational thought seems to go out of the window.
In 2007, a woman phoned South Wales Police to report a ‘bright stationary object’ that had been floating in the air for 30 minutes.
Later that evening, the police control room radioed to check what an officer had found.
The officer replied: “It’s the Moon. Over.”
The International Space Station
The International Space Station is larger than Wembley’s football pitch and significantly brighter than most night sky objects.
It moves fast, taking just a few minutes to cross the sky from one horizon to the other.
It’s also silent, perhaps startling and confusing onlookers who are used to the din of aeroplane engines.
Oddly shaped clouds
The closest you’ll get to seeing a classic flying saucer shape is the so-called lenticular cloud (Altocumulus lenticularis).
They form at high altitudes, near or atop mountains that have moist air blowing over them.
Although the wind speeds are high, the clouds remain stationary.
It’s not hard to imagine you’re seeing a hovering UFO, or a saucer concealed inside the cloud.
Paper lanterns are increasingly popular.
Once lit, they can float very high – up to a mile, according to some reports.
The fact that they make no sound and have an orange glow adds to the sense of mystery, especially if you see them flying in ‘formation’ (due to them being tied together with string).
In the 1970s the US Navy launched a series of surveillance satellites to track Russian vessels.
Dubbed NOSS (Naval Ocean Surveillance System) by civilians, each consists of a trio of satellites that orbit in a triangle formation and are sometimes visible to the naked eye.
Search YouTube for ‘NOSS satellite’ to see if you’d mistake them for a black, triangle-shaped spacecraft.
Seen either before sunrise or after sunset, Venus is so bright it’s often mistaken for the landing lights of an aeroplane.
Unlike a plane, though, Venus is pretty much stationary, which gives imaginative observers the impression of something ‘hovering’.
The bright, orangey red Jupiter is another planet frequently taken to be a UFO.
There are 66 working Iridium communication satellites in orbit, each of which is equipped with a highly reflective antenna that points to Earth.
At some point in its orbit, this antenna will reflect sunlight straight down.
For a few seconds, this creates a flare in the sky, which is so bright it often outshines all other night-time phenomena.
This article first appeared in the November 2009 issue of BBC Sky at Night Magazine.