War of the Worlds Illustration

“So, where are they then?” That question, allegedly posed in 1950 by physicist Enrico Fermi, neatly captures the contradiction between the apparently high probability of extraterrestrial life and the complete lack of evidence for it. It’s a mystery that’s never far from the surface in Alien Revolution, the Royal Observatory’s new exhibition exploring our changing perception of alien life from the 16th century to the present day.

The story told by this small, family-focused exhibition – accompanied by a varied programme of film screenings, workshops and talks – begins with Copernicus. When the Polish astronomer realigned our perception of the universe, it argues, he also initiated an “unintended alien revolution”. The heretical proposition that humankind might not be the centre of the universe opened up the possibility that there could be other beings on other worlds. By 1600, the Dominican friar and avowed Copernican Giordano Bruno was arguing for “the existence of a plurality of worlds”, a heresy for which he was burned at the stake.

The first systematic account of extraterrestrial life came from Dutch astronomer Christiaan Huygens, best known for explaining the nature of Saturn’s ring system and discovering its moon Titan. In his Cosmotheoros (or The Celestial Worlds Discover’d: or, Conjectures Concerning the Inhabitants, Plants and Productions of the Worlds in the Planets), published shortly after his death, in 1698, Huygens goes into extraordinary detail about a hypothetical alien race. Contemporaries accused the work of being unscientific – some claim today that it was ironic – but whatever Huygens’s intentions, his aliens’ “great round saucer Eyes” are strikingly reminiscent of the late 20th century’s archetypal extraterrestrial.

The high likelihood of life on other celestial bodies was accepted by many of the greatest figures in astronomy. “For if all places to which we have access are filled with living creatures, why should all these immense spaces of the heavens above the clouds be incapable of inhabitants?” asked Isaac Newton in 1701. William Herschel, who discovered Uranus in 1781, went even further, arguing for life on planets, moons, comets and asteroids; he even speculated that the sun was inhabited “by beings whose organs are adapted to the peculiar circumstances of that vast globe”.

But more than 400 years after Copernicus first challenged the geocentric model, we had still not seen any signs of extraterrestrial life. In 1960 – as if frustrated by this lack of progress – astrophysicist Frank Drake began the first search for radio transmissions from distant solar systems, at the National Radio Astronomy Observatory in Green Bank, West Virginia. The next year, Drake chaired a historic meeting of astronomers that established the search for extraterrestrial intelligence (SETI) as a scientific discipline in its own right.

In preparing for the meeting, Drake developed a new approach to estimating the number of alien civilisations in our galaxy. Using this “Drake equation”, the participants (including a young Carl Sagan) decided the Milky Way could harbour anything between 1,000 and 100,000,000 civilisations. But decades later, the experiments and initiatives that sprang from this meeting – including, in 1984, the founding of an institute devoted to SETI research - have yet to discover any meaningful transmissions. The “great silence” continued.

Alien Revolution is not just a story of astronomers and astrophysicists, however. It also explores the place of aliens in science fiction, where they have long been deployed to articulate very human concerns: about race, gender, disease, imperialism and, more recently, environmental catastrophe.

As the nature of these preoccupations changed, so did the forms that fictional aliens took. Early depictions still owed much to Christian iconography; the hairy bat people from the New York Sun’s 1836 satire on alien-obsessed astronomers (pictured, above) would look at home in a renaissance Last Judgement. But by the late 1940s and the golden age of science fiction, aliens could be slimy, feathered, bug-eyed or scaled. They could look like lobsters, turtles or grasshoppers, with any number of limbs and a range of other sinister appendages.

Alien Revolution doesn’t mention Charles Darwin (a disappointing omission) but it seems likely that his theory of evolution by natural selection drastically expanded the imaginative possibilities of science fiction. Aliens were no longer simply humans on other worlds, but separate species with their own evolutionary path. It was an idea embraced not only by writers of fiction but by biologists such as Harold Blum, who argued in the 1950s that if alien life existed it would probably be radically different from our own.

Another thread of Alien Revolution, caught somewhere between science fiction and science fact, is the phenomenon of UFO sightings and abductions: from Kenneth Arnold’s sighting of the first “flying saucer” over Mount Rainier in 1947 – he actually claimed to have witnessed a cigar-shaped craft move like a saucer – through the first reported alien abduction of Betty and Barney Hill (pictured, bottom right) in 1951 to the crop circles that began appearing in the English countryside in the 1970s.

And as long as there have been reports of strange lights in the sky, there have been those who have collected and analysed them – officially and unofficially – in the hope of uncovering the truth. The 1980s are often viewed as the golden age of “ufology” in Britain, with active UFO study groups springing up across the country. Energised by a handful of important sightings, the groups’ findings were disseminated through a vibrant newsletter and magazine scene, bringing together a mix of arch-sceptics, true believers and every position in between.

The growth of ufology continued into the 1990s, but the new millennium heralded a sharp decline in interest. In 2002 the X-Files TV series – once a PR dream for ufologists – ended with half the viewers it had enjoyed at its peak. Two years later the British UFO Magazine, a respected chronicler of the ufology scene, folded after a quarter of a century. Then, in 2009, the Ministry of Defence announced that its dedicated UFO hotline would be closed down, explaining that “responding to reported UFO sightings diverts MOD resources from tasks that are relevant to Defence”.

Not everyone accepted that explanation. Elements within the ufology community had become increasingly preoccupied with the “disclosure agenda” – the belief that extraterrestrial contact had taken place and was being covered up by government agencies. They saw the supposed end to official UFO investigations as a stunt designed to deflect attention from the real goings-on at the MOD. But even those who didn’t quite buy the idea that ministers had been holding secret summits with aliens questioned the government’s decision. What the MOD insisted was a prosaic bureaucratic process – noting sightings, assessing any potential defence impact, then filing away – many in the ufology community liked to characterise as a British X-Files.

This view was apparently substantiated by former civil servant Nick Pope, who, for three years in the 1990s, was responsible for investigating UFO reports at the MOD. Pope left the MOD in 2006, but, when the news broke that the hotline would be closed down, he quickly found a media career as the British Fox Mulder, at times claiming to have been abducted by aliens himself. The more rationalist ufologists point out that dozens of people had investigated UFO sightings for the MOD, and only Pope claimed it was anything more than a monotonous desk job. Nevertheless, the community became more and more obsessed with conspiracies.

All of which contributed to ufology’s decline, but another development in the 2000s would be its death knell: the rapid growth of smartphones, affordable digital cameras and the internet. In the past, people would witness a strange event, share their experience with others, and the story would grow through hearsay and hyperbole. But by 2006 half the world’s phones had a built-in camera and many also had the capacity to make videos – the nature of “sightings” had changed irrevocably.

“Instead of these eyewitness accounts, if people see something now they whip out their camera phone and they start recording it rather than viewing it,” explains Dave Wood, chair of the Association for the Scientific Study of Anomalous Phenomena (ASSAP). “And when people look at these things on YouTube they are fairly obviously not unexplained flying objects. They have some kind of prosaic explanation.”With technology gradually stripping the subject of its mystery, and the number of fresh sightings dwindling, the ufology community became increasingly fixated upon a handful of canonical cases such as Rendlesham Forest, where in 1980 dozens of US Air Force personnel – who were using nearby RAF Woodbridge – reported strange lights in the sky.

“It’s now quite a backward-looking subject, focusing more energy on reanalysing what happened in the 1980s and 1950s, those seminal UFO cases, rather than there being a present that’s being studied,” says Wood, who last year organised an ASSAP summit on what it called the “crisis” in ufology. Without a supply of new sightings to investigate, UFO study groups became increasingly redundant. At ufology’s peak in the mid-1980s there were 130 local study groups in the UK; today there are just 30.

Ufology’s rationalist wing felt increasingly outnumbered and embattled. “There’s nothing to be gained from being a sceptic,” says David Clarke, senior lecturer in journalism at Sheffield Hallam University and author of The UFO Files, which traces a century of UFO sightings through formerly secret government records. “No one wants to read your stuff, you become an Aunt Sally. They blame the fact that the truth hasn’t come out on the dirty sceptic debunkers who have been working with the government to suppress the truth. Who’s going to put up with that?”

Most of those who pursued a rationalist approach to ufology have come to accept the “cultural tracking” theory: that UFO encounters reflect the political concerns and popular culture of the time in which they occurred, rather than objective reality. Cultural tracking is often straightforward – such as the spate of sightings following the release of the film The Day the Earth Stood Still – but the effect can work more subtly. Consider Roswell, the most famous UFO case of all time. The events happened in 1947, yet it is barely mentioned in ufologist literature until the late 1970s.

Why? Some suggest that post-war America simply couldn’t countenance the idea that a government would conspire to keep secrets from its citizens – not until the Watergate scandal in 1974, that is. After Nixon’s resignation, Americans began to seriously question whether their governments had their best interests at heart – and Roswell suddenly had cultural resonance.

UFO encounters also tend to increase when aliens feature prominently in film and TV, but recent science fiction seems to have become less preoccupied with what is out there than with what the future holds for us here on earth. The post-apocalyptic genre in particular – whether the cause of Armageddon is zombies, genetically engineered diseases or nuclear war – has enjoyed a revival in recent years. There’s been a resurgence of interest in vampires, werewolves and witches, too, thanks to Harry Potter and Twilight and their numerous imitators.

But could a ufology renaissance be just around the corner? “I think it goes in waves and troughs,” says Clarke. “If you go back to its earliest origins it’s gone through numerous crises. I was flicking through back copies of Flying Saucer Review and I came across one from 1963 or ’64 and there was a piece in there asking: ‘Is this the death of the subject?’”

Alien Revolution does give us some cause for hope, emphasising Astronomer Royal Martin Rees’s recent suggestion that we could find evidence for extraterrestrial life within 40 years. It also highlights the discovery by NASA’s Kepler telescope of KOI-172.02, the most Earth-like planet yet. And in March, just after the exhibition opened, the Mars rover Curiosity discovered clay minerals that may have been formed in neutral water – an indication that the planet could once have supported life. So perhaps an answer to Fermi’s question is closer than we thought.

Alien revolution is at the Royal Observatory, Greenwich, London until 3 September