Astronomical Causes of UFOs

In recent years, I have seen a number of videos taken with hand-held camcorders which appear to show saucer-shaped objects making erratic motions in the evening sky. These videos are clearly of Venus in twilight. The “movement”, noticeable only when the camera is zoomed in, is due simply to tremors in the hands of the excited camera operator, while the apparent shapes of the objects are optical effects in the camera itself. Parenthetically, video evidence has also made it clear that many daytime UFOs are now caused by small, shiny helium-filled balloons of the type given out at fairgrounds. In addition, a type of rotating reflective kite called the UFO SAM has made its own contribution to sightings. More recently, small decorative hot air balloons called Sky Lanterns or UFO Balloons have joined the list of culprits, generating reports of orange-coloured “saucer fleets”. (For more about fire balloon misidentifications and pranks, see here and here). Another addition to the list, brought to my attention by someone who was temporarily fooled by one at night, are kites and balloons designed to scare birds. Even black plastic bags, when heated by the Sun, can become UFO-like balloons.

Getting back to astronomy, it is understandable that people can misidentify planets and bright stars – but surely not the Moon? Yet it happens. Allan Hendry describes a case in which three witnesses observed a saucer “25 ft in diameter” accompanied by two pulsating lights which hovered over a car park for nearly an hour, dimming the car park lights as though draining power from them. A humming noise was heard which changed to a loud beeping before the saucer shot straight up into the sky. A parakeet owned by one of the witnesses screeched and her dogs barked. The woman felt as though she was in a trance and could hardly move.

This has all the hallmarks of a classic UFO case: electromagnetic effects, animal reactions, and physical effects on the witnesses. However, Hendry determined that the witnesses were looking at the crescent Moon (the “saucer”) with Mars and Jupiter next to it (the “pulsating lights”). The dimming of the car park lights was caused by intermittent mist which eventually obscured the Moon and planets. The rest of the report is a marvellous product of human imagination.

Meteors (bits of dust and rock from space burning up in the atmosphere to produce a briliant streak of light) are less easy to identify after the event because of their transient nature. Humans are as bad at estimating time as they are at estimating brightness and distance, and reports often exaggerate the duration for which a meteor was seen. Very bright meteors – say, brighter than the planet Venus – are termed fireballs. These are so bright they can be caught on normal video cameras, and a fascinating selection of sightings can be found on this page – particularly impressive is the Perth fireball of 2005, filmed by chance during a family party at a house in Western Australia, which generated widespread reports of an aircraft crash [2.5 MB AVI file].

Even experienced pilots can make major errors of identification and distance

Even people familiar with normal meteors can be fooled by unusually bright fireballs. Here is an example quoted by Philip Klass in his book UFOs Explained (Random House, 1974). Pilots aboard a commercial jet flying at 39,000 ft over the United States in 1969 were reportedly buzzed in daylight at a distance of 300 ft by a formation of four objects emitting a blue-green flame. A military jet flying some miles behind the airliner reported a squadron of UFOs approaching that suddenly started to climb as if to avoid a collision.

At the same time as this UFO “encounter”, a brilliant daylight fireball broke up into several flaming pieces over the United States, and there seems little doubt that this is what the pilots saw, despite the fact that it was actually over 100 miles away from, them. So even experienced pilots can make major errors of identification and distance. That doesn’t make them bad airmen, simply human. The encounter near Manchester reported at the start of this article seems to have been a more modest example of the same thing. For an example of how a brilliant fireball and bright stars featured in a multi-witness sighting involving the US Air Force, see my investigation of the celebrated Rendlesham Forest UFO case.

Even sightings involving military radar are no more likely to involve “genuine” UFOs. In 1989 a series of reports began to emanate from Belgium, culminating on the night of 1990 March 30–31 with widespread sightings by police and an aerial “chase” by Belgian Air Force F-16 fighters involving radar contact with an unidentified target. This now-famous event turned out to have been sparked off by misidentifications of bright stars and planets while the radar returns were due to atmospheric effects and equipment malfunction. (For a more extensive analysis, see here.) Faced with cases such as this and Rendlesham, both still declared unexplained by some UFOlogists, one wonders how far it is possible to credit any UFO report.

Over half a century after the launch of Sputnik 1, many people are still surprised to find that orbiting satellites can be seen from the ground with the naked eye. Satellites have tricks that can fool even experienced observers. Some satellites flash as they rotate; others travel in convoys, including triangular formations; and others fade and disappear as they enter the Earth’s shadow, giving an effect that is sometimes described as “vanishing rapidly upwards”.

If real alien spacecraft were whizzing around in orbit they would rapidly be noticed both by amateur satellite spotters and by defence radars.

A more recent breed of UFO culprits is a series of satellites launched to relay signals for the Iridium mobile phone system. There are over 70 of these, launched since May 1997, and they have highly reflective aluminium antennae which can catch the Sun, giving sudden spectacular glints far brighter than any star or planet, lasting for a few seconds. Such sudden brightening followed by fading may give the impression of something rapidly approaching and then receding.

I have mentioned the zig-zagging of satellites due to effects in the eye. In his collection of essays The View from Serendip (Gollancz, 1978), Arthur C. Clarke described an unexpected sighting of the balloon satellite Echo which appeared to stop and hover overhead before resuming its onward path. The reasons, as he realized afterwards, were that he and film producer Stanley Kubrick, who was also watching, were too excited to observe calmly; it is almost impossible to assess the motion of something overhead; and moonlight had swamped the background stars against which the motion could be judged.

Echo, a particularly brilliant satellite, re-entered long ago, but many other bright satellites have taken its place, notably the International Space Station. If real alien spacecraft were whizzing around in orbit they would rapidly be noticed both by amateur satellite spotters and by defence radars which are actually designed to look for spaceships – our own.

Finally, satellite re-entries occur on a daily basis. In appearance they are similar to fireballs but can be brighter, longer-lasting, and slower-moving. As a man-made object burns up it usually fragments into numerous pieces, giving the impression of a cigar-shaped UFO with portholes.

For instance, a widely reported sighting over the British Isles early on 1993 March 31 termed the Cosford Incident is now known to have been caused by the re-entry of the rocket that launched the Russian Cosmos 2238 satellite into orbit, combined with the misidentification of a police helicopter by a meteorologist at an RAF base an hour and a half later. Yet the MoD investigator at the time, Nick Pope, declared: “It seems that an unidentified object of unknown origin was operating in the UK Air Defence Region without being detected on radar.” Hence another solved case has come to be regarded by some as an officially recognized UFO.

Satellite predictions, including flashes from Iridium satellites, can be obtained for any location in the world from the web site hosted by the German Aerospace Centre (DLR) on http://www.heavens-above.com

Good UFO spotting!

Content last updated 2009 June