Did you see these headlines this week? "Secret report says UFOs DO exist", screamed one. "UFOs don't exist, says MoD", said another. Confused, intrigued and potentially a little disappointed, I tried to find out what was behind the flurry of flying-saucer excitement.

It turns out to have all stemmed from a 'secret report' by the UK's Ministry of Defence (MoD), which was unearthed by sleuthing academic David Clarke, a lecturer in investigative journalism at Sheffield Hallam University, UK. Clarke spent 18 months using the Freedom of Information Act to extract the report, authored in 2000, partly as a test-case exercise in exploiting the Act, he says.

The main upshot of the report is that 'unidentified flying objects' technically do exist, but are mostly sightings of aircraft or odd weather phenomena. Fair enough. But the media flurry over the report has struck me as at least a little odd. Many of them unquestioningly stated that MoD "scientists" have explained how balls of glowing plasma in the upper atmosphere could be mistaken for flying saucers, and that these plasma balls could in turn interfere with the brain, somehow conjuring up vivid abduction memories. This stems from a bit of the report's summary, which says: "Local fields of this type ... have been medically proven to cause responses in the temporal lobes of the human brain".

So is this a solid, scientific explanation for UFO sightings? Sadly, no.

Top secret

The MoD document compiles UFO sightings reported to the ministry over previous decades. But the top-secret nature of the project meant that none of the UFO witnesses were questioned further about their experience. "That's the weakness of the report," says Ian Ridpath, an astronomy writer and UFO-debunker from Brentford, UK, who was a guest speaker at Clarke's press conference on 8 May. No scientists were directly consulted, and the author relied instead on literature searches, says Clarke. It even appears to rely on some pretty "dodgy" theories put about in UFO folklore, he adds.

Clarke suggests that whereas the MoD had claimed for years that UFOs posed no threat, internal memos reveal that in the late 1990s they realized that the department wouldn't actually be able to back up that assertion if pressed on the issue, and needed a report to fall back on. The identity of the author is still unknown, although Clarke believes it was a retired RAF pilot.

A helpful MoD spokesman tells me that he cannot confirm or deny who wrote the report, or how it was prepared, because he doesn't know. "There's not even an official I can call up to find this out," he sighs. "We don't have any UFO experts, frankly." He points out that unidentified flying objects (although they prefer the term 'unidentified aerial phenomena') do of course exist, since people see plenty of things in the sky that they can't identify. "But they become an FO pretty quickly," he says.

So does the document actually provide any new, solid evidence?

"All it does is re-emphasize what sceptics have already known," says Ridpath. He points out that the ideas about electrical plasmas being mistaken for alien craft are far from being a new idea.

Mind-altering electrics

Aliens? Nope. Just 'sprites' in the atmosphere above Kansas.Credit: Walter Lyons, FMA Research, Fort Collins, Colorado

Such 'sprites' are triggered when lightning rips electrons away from nitrogen molecules in the upper atmosphere. Although they only exist for tens of milliseconds, chains of consecutive sprites can appear to move through the sky, explains Martin Füllekrug of the University of Bath, UK, who researches these electrical events.

What about the mind-mangling electric fields? At 20 kilometres altitude, Füllekrug thinks it highly doubtful that these transient plasmas could have much effect. On the ground, the similar phenomenon of 'ball lightning' has been described, but is little understood. Whatever these are made of, such earthly plasmas are likely to have such a weak electromagnetic field that they are pretty unlikely to register on scientific equipment, let alone the human brain, says Füllekrug.

"The science it's been based on is very questionable," agrees Clarke. "When meteorologists and physicists read it there'll be a lot of chuckling," he predicts.

Totally open-minded

To be fair, the report is quite clear that it is not meant to be a rigorous study of the science behind UFO experiences; just an assessment of military risk. (Although given that it says plasma balls can affect our brains, I wonder how exactly they can stick with the assessment that there isn't a risk).

As a ministry official points out in a Freedom of Information Act correspondence file , "The MoD does not have any expertise or role in respect of 'UFO/flying saucer' matters, or to the question of ... extraterrestrial life forms, about which it remains totally open-minded." Reassuringly agnostic, I think.

You can see the full report and judge for yourself when it is put up on the MoD website on 15 May. It wasn't made public in 2000, says the ministry spokesman, simply because they didn't think it added much to the debate.

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