WHERE (ON EARTH) have all the unidentified flying objects gone? Just a few years ago, the sky seemed to be littered with flying saucers and every other sort of astral crockery: strange lights, cigar-shaped spaceships, paranormal things that went bump in the night. Scully and Mulder were rushed off their feet.

Now the UFOs have almost vanished. Sure, you still get a few alien abductions, especially on New Year’s Eve, and diehard ufologists are still recording close encounters of the umpteenth kind. Since 1955 the National UFO Reporting Centre in Seattle has clocked 125,000 reports of sightings. But in recent years the numbers have dropped dramatically. The British Flying Saucer Bureau closed down three years ago after half a century of saucer-spotting. The simple truth is that the little green men don’t come calling like they used to, and they have stopped leaving circles in our crops.

One explanation for this is that the aliens have realised that this poor little planet is dying, and not worth visiting any more. But leaving aside the possibility that we are simply an interplanetary holiday destination that has fallen out of fashion, the withering of the UFO craze represents a fascinating shift in human credulity, the end of a cultural phenomenon that reached its apogee in the late 20th century.

But it is also a result of human invention, and humanity’s evolving relationship with new technology. UFO sightings have declined as the internet has expanded. The web is the natural home of every crackpot and conspiracy theorist, but it also, eventually, produces a rarefied atmosphere of rationalism in which aliens and other elusive creatures cannot long survive. In the short term, the internet was a blessing to UFOs; but over time, it has all but killed them off.

Humans have been spotting odd things in the sky from the dawn of time. Egyptian scrolls from the 15th century BC tell of “burning circles” in the heavens, the Book of Ezekiel describes celestial wheels of fire and in AD98 a shield-shaped thing hurtled across the Roman firmament. Before the First World War there were regular sightings of phantom Zeppelins.

UFOs tend to appear at moment of turmoil and technical innovation, and the full-scale alien invasion started after the Second World War. On June 24, 1947, an American pilot named Kenneth Arnold spotted nine silvery objects hurtling through the air near Mount Rainier in Washington state. The term “flying saucer” was born, a good example of bad journalism since Arnold had specifically stated that the objects were shaped like boomerangs.

Within a month, flying saucers had been reported in 28 states. On a ranch near Roswell, New Mexico, the US Air Force recovered bits of debris from a crash site, and rumours of bodies of bug-eyed aliens quickly spread. Britain became a favoured UFO landing strip, with hundreds and then thousands of reported sightings. “What does all this stuff about flying saucers amount to?”, wondered Winston Churchill in a memo written in 1951. “What can it mean?”

In part, the alien spaceship invasion was a reaction to the stresses of the Cold War and the nuclear age; in a time of technological frenzy, space exploration and paranoia, the notion of alien visitors was increasingly acceptable, even comforting. In the same way that our medieval forebears saw angels and comets at times of plague and catastrophe, we saw lights and visitations in the night sky as the world seemed ever more dangerous, and other planets drew ever closer.

The high point for UFO spotters came in the mid-1990s. The fields were festooned with crop circles; The X-Files was required watching, the men in black were everywhere. In 1994 some black-and-white film footage turned up, purporting to show military scientists performing a post-mortem examination on two of the Roswell aliens: small, humanoid creatures with six fingers on each hand and six toes on each foot, without belly buttons or hair. The film, since exposed as a crude forgery, was taken seriously enough for journalists (including this one) to be dispatched to Roswell to report on the discovery.

The early internet helped to power the UFO phenomenon: instant myths, sightings, secrets and lies scorched around the world wide web. But the web also helped to undermine faith in the paranormal. In the age of instant text messaging and universal webcams, spotting UFOs, photographing them, posting the evidence worldwide and calling in witnesses should have been far easier than ever before. As Douglas Kern writes in a trenchant article for TCS Daily: “Just as our technology for finding and understanding UFOs improved dramatically, the manifestations of UFOs dwindled away.”

Instead, the UFOs have scarpered. The internet works by taking in vast swaths of hokum and ignorance but it gradually sifts out the chaff. Errors inevitably creep, for example, into Wikipedia, the online encyclopaedia, but because this is a self-creating and self-regulating mechanism, the mistakes and the nonsense are weeded out, or wither away. For every soothsayer and rumour-peddler on the web, there is a rationalist, an expert, a sceptic, calling for common sense. The truth will out, eventually.

The UFOs are still whizzing about up there, for sure; they just tend to crash faster these days. This month, residents of Orange County, California, spotted mysterious discs hovering over the town of Aliso Viejo. The sightings were swiftly recorded by a UFO research website, ghostly blue lights that “danced around one another in the night sky”. The news hurtled around the web, UFO chat rooms buzzed with excitement.

Ten years ago the Aliso Viejo sightings would have swiftly entered UFO folklore, passed from one believer to another. But no sooner had the Orange County saucers been launched, than a cardiovascular surgeon named Gaylon Murphy admitted the UFOs were radio-controlled foam disks fitted with flashing lights, which he had built in his garage. “We fly them in formation,” he said. “It’s pretty funny.”

The Aliso Viejo UFOs are still on the internet, but now entirely overshadowed by more mundane normality: “It came from the Planet Garage.”

The unidentified flying object has been identified, and cannot fly any more. ET has gone home.

Read more Ben Macintyre columns: www.timesonline.co.uk/benmacintyre

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