Two of the most common questions if you are a scientist and, particularly, an astronomer are: “is there life on other planets?” and, “what do you think of UFOs?”

I will start by answering these two questions:

Of course, there is life “out there”. History has shown that every time we take a geocentric or a human centric view of the Universe and consider ourselves, or our planet, special in some way, we have been completely wrong. However, the distances between extra-terrestrial civilisations are such and our Sun and our Earth are so obscure that the chances that anyone has, or ever will visit us, are very remote.

If you spend a lot of hours watching the sky and are observant, you will see a lot of UFOs and a bit of imagination can make them very convincing. A UFO is just any object in the sky that you cannot immediately explain, but that does not make then spaceships visiting from other planets. I have seen some wonderful UFOs, a few of which looked convincing until I kept watching for long enough to figure out what they were. There is only one UFO that I genuinely cannot explain and that one I am absolutely sure had a simple explanation, but I could not work out what it was.

However, the UFO community has been so mixed up with fraud, with conmen who try to fool the credulous, that the very term “UFO” – Unidentified Flying Object – has become discredited. It is so identified with those people who want to make money from fooling people into seeing what they want to see, that the very word itself has become little more than a joke.

Similarly, the UFO phenomenon gets mixed with all sorts of other phenomena and mysticism such as crop circles, pyramidology and many other subjects that have left the serious investigation of UFOs in disrepute.

Over the years, I have read not a few books on UFOs and met a few well-known flying saucerers. Many of the techniques of selling their product are simple. For example, a series of books, by a widely publicised and widely read author in the 1960s (my local Public Library had them on the shelves) took some highly over-exposed photographs of Saturn and its satellites taken from a large, American observatory, that washed the planet out into a large saucer and labelled them as “a mothership and its subships rendezvousing”. Millions of people around the world were prepared to believe him. Others took believers out on flying saucer observing tours at night and, by art of magic, managed to turn a predicted pass of the Skylab space station into a highly believable UFO sighting. Of course, the guide knew that Skylab would be visible that night, but did not mention that fact, either before or after, to his spellbound audience, who left him, convinced that flying saucers were real.

Other well-known cases involved strange lights seen at night on a beach by a major international airport, with its famous “Magic mountain”, a landmark at the end of the beach, which was said to be a UFO base (what the air traffic controllers at the airport were doing to earn their living if there were, genuinely, hundreds of flying saucers flitting around unseen, presumably without having filed flight plans, is not explained). The proof of existence of this UFO base was the large number of sightings late at night of strange lights seen on the beach and towards the mountain. The fact that the beach was (and still is) a busy entry point for contraband (mainly tobacco), provided an alternative and more terrestrial explanation that was not as widely publicised as the flying saucer theory! Similarly, a giant flying saucer watch, organised in a large nearby national park, drew thousands of members of the public to pass the night watching the skies: the organisers saw dozens of UFOs but, strangely, the large group of amateur astronomers who had joined the gathering, only saw some artificial satellites and the occasional meteor!

Of course, not all members of the flying saucer community are simple frauds and conmen: many genuinely and passionately believe that what they have seen is real and that it is alien and are looking for the proof that confirms their beliefs: these people tend to get very angry if anyone casts doubt on what they saw and suggests that it may have been perfectly natural.

Over the years, scientists have become aware of more and more unusual natural phenomena that explain many strange sightings. Decades ago, the lenticular clouds that form in the lee of mountains were a regular source of flying saucer reports. Now, thanks to their regular publication in TV weather reports, it is rare that the public confuses them. However, a host of phenomena, natural and artificial have been added to the scientific bestiary. Ball lightning, sprites, foo-fighters, marsh lights, noctilucent clouds (currently being observed further south than ever before), STEVE, Cyrillid meteor streams and many other natural phenomena are being increasingly widely documented: it is an interesting test to see how many of these terms the average non-scientist has ever heard of. Fewer and fewer people are familiar with the sky as part of their daily life, making sightings of these, rarely observed phenomena easy to confuse with the supernatural. Even one United States President – still active in a UN role – sighted Venus on one occasion and reported it as a UFO. Other, very famous UFO sightings were found to be more prosaic. During the 1950s, hundreds of people reported strange lights flying in formation over the town of Lubbock in Texas. These became known as the Lubbock lights (the feature image to this article) and one of the most famous UFOs of its time. It was not until a local ornithologist heard the call of plover as “the alien craft flew over” that the explanation became obvious: the birds were reflecting the streetlights off their oily chests!

Nowadays, satellite fuel dumps, Space Station passes (the International Space Station is the fourth brightest object in the sky, after the Sun, the Moon and Venus) and Starlink trains all appear inexplicable to the average member of the public, who sees them without knowing what they are. It is not hard for a member of the public to turn, in his or her imagination, dozens of Starlink satellites, flying in formation, into Kenneth Arnold’s famous formation of flying saucers that he described, in 1947 as “like saucers skipped over water”.

As Hamlet comments to Horatio:

“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”

Of course, in 99.9% of occasions, there is a rational explanation, but the observer does not recognise the phenomenon, or the observer’s report is too incomplete, or too inaccurate to allow an explanation. This, of course, is parodied in science fiction films when the puzzled hero stammers, “there must be a rational explanation” just before the aliens kidnap him and carry him off (for some reason it is always a man who utters this phrase).

Another problem with UFO reports is deliberate misinformation. This can manifest itself in many ways. There is a goodly body of UFO reports from the southern United States, in which people reported strange lights moving at high speed up the Mississippi Valley. The US Air Force reacted by saying that none of their aircraft were in the area and that they had no explanation for the lights. In fact, the key word is in italics: they were none too keen to admit that Cuban MiGs were penetrating, unmolested, hundreds of kilometres into the interior of the United States. Similarly, many reports of strange craft around the world in recent decades, are attributable to test and, later operational flights of stealth technology: neither the Russians, nor the Americans, nor for that matter, anyone else who has the technology wants it too widely advertised so, encouraging people to think that they have seen a UFO diverts attention from what they saw really.

Among the hard core of difficult to explain reports are those from military pilots. Over the years, there have been a number of these, but the release by the Pentagon of three videos obtained by the targeting cameras of US Navy pilots in November 2004 and in January 2015 has started a whirlwind of speculation. Two of the objects are high altitude and are seen above the cloud tops; the third is apparently small and evidently at very low level as it skims above the waves. In each case, the pilot’s reaction was amazement and excitement.

There have been various projects to collate UFO reports over the years by the military and agencies such as NASA. The US Air Force’s “Project Blue Book” is probably the best known of these. It compiled 12618 sightings from 1947 to 1969, when it was finally terminated.  Of the sightings, 701, representing 5.6% of the total, are classed as unexplained. The full text of Project Blue Book is compiled on 94 rolls of microfilm in the National Archives in Washington and detailed in the Web of the National Archives, which carries a summary of information about Project Blue Book and even about the Roswell Incident, among other related information.

The conclusion of Project Blue Book was:

 (1) no UFO reported, investigated, and evaluated by the Air Force has ever given any indication of threat to our national security;

(2) there has been no evidence submitted to or discovered by the Air Force that sightings categorized as “unidentified” represent technological developments or principles beyond the range of present-day scientific knowledge; and

(3) there has been no evidence indicating that sightings categorized as “unidentified” are extra-terrestrial vehicles.

However, since November 2004, the Pentagon has started compiling reports again, because of renewed concerns about points (1) and (2) above. At the request of the United States Senate, an initial, unclassified report was released, after much anticipation, on June 25^th (yesterday). This report covers 144 sightings reported between November 2005 and March 2020, of which only one could be explained. However, most of the reports have been compiled in the last two years as formal reporting mechanisms have become established and as the report admits, the “stigmas [associated with reporting] have lessened”.

You can read the report here. It is disappointingly thin: the meat of the report is just under four pages long and, with introduction and appendices, it is just nine pages in total. However, there is some fascinating detail, both in what it says and in what it does not say.

One of the key details of the report is that nowhere is the classic and discredited name “UFO” mentioned: sightings are termed Unexplained Ariel Phenomena, or UAF. A second is that eighty of the sightings “were registered across multiple sensors, to include radar, infrared, electro-optical, weapon seekers, and visual observation”, in other words, they cannot be explained away as camera or radar glitches. This leads to a third, fundamental conclusion: “most of the UAP reported probably do represent physical objects”: i.e. yes, those pilots really did see and detect something and was not being fooled by mirages, or Venus, or…

Given the recognition that UAFs are genuine, physical objects, two further conclusions of the report are extremely interesting:

• “UAP pose a hazard to safety of flight and could pose a broader danger if some instances represent sophisticated collection against U.S. military activities by a foreign government or demonstrate a breakthrough aerospace technology by a potential adversary… The UAPTF has 11 reports of documented instances in which pilots reported near misses with a UAP.”
• “A handful of UAP Appear to Demonstrate Advanced Technology. In 18 incidents, described in 21 reports, observers reported unusual UAP movement patterns or flight characteristics. Some UAP appeared to remain stationary in winds aloft, move against the wind, maneuver abruptly, or move at considerable speed, without discernable means of propulsion. In a small number of cases, military aircraft systems processed radio frequency (RF) energy associated with UAP sightings. The UAPTF holds a small amount of data that appear to show UAP demonstrating acceleration or a degree of signature management.”

These two conclusions represent a big change in attitudes since Project Blue Book was closed. There is a recognition that there is something there and that, at least in some circumstances, it could even be dangerous. So, what are UAPs? The only conclusion included in the report is that “analysis of the data supports the construct that if and when individual UAP incidents are resolved they will fall into one of five potential explanatory categories”:

1. airborne clutter – this can be anything from plastic bags or other rubbish lifted into the atmosphere and swirling around in the wind, to drones, balloons and large birds, all of which can confuse a pilot who may not be able to estimate accurately the size, distance and speed of the object.
2. natural atmospheric phenomena – some types of natural phenomena can register on sensors (think of, for example, rain radar).
3. US Government or industry developmental programs – secret programmes belonging to government or industry.
4. foreign adversary systems – Russian, Chinese, or other (maybe someone has advanced technology that the USA does not have).
5. Other – a small number cases showing unusual motion that cannot easily be fitted into the previous categories and that may require more advanced science to explain, or may be due to something spoofing sensors, i.e. causing false readings, or to sensor errors. These reports need deeper analysis.

Of course, the “other” category, could even include extra-terrestrial origin, a point picked up by the Press although not explicitly mentioned in the report itself. Common sense, though, tells us that we should exhaust other possibilities first before embarking down that path. For one thing, any technology sufficiently advanced to allow other civilisations to visit us would be, even in the best of cases, centuries in advance of ours and there is no reason why they would allow themselves to be seen in the first place. Most definitely, if UAF are extra-terrestrials observing our planet, they are doing it in a very peculiar way. If an alien civilisation really did want to make its presence known, a landing at Kennedy Airport, or on the White House lawn would probably be the best way to do it! That said, the culture shock involved in such an encounter would be immense: it would involve a cultural and a technological gap far greater than between the Native Americans and the Conquistadores (and we know how well that went for the less developed culture).

Estimates of how many technological civilisations there may be out in our galaxy range widely from the pessimists, who argue that in all probability we are alone in the Galaxy, to the optimists, who suggest that the number may be in the thousands, or even the millions. Either way, the philosophical implications of that number are mind-blowing. What though do these numbers actually mean?

Let us suppose that there are a million technological civilisations “out there”, which would be at the high end of the most optimistic numbers, proposed by the people who think that our Galaxy is teeming with advanced civilisations. That means that about one in a hundred thousand star systems has a technological civilisation. The average separation of stars in the Milky Way is about five light years, which would imply that, even in this incredibly optimistic case, technological civilisations are an average of 800 light years apart in the Galaxy. That is an enormous distance. From 800 light years away, our Sun would be a tiny dot of magnitude 12. If, instead of a million civilisations, there were just one hundred in the galaxy, the distance between them would be more like 10000 light years.

Let us suppose that now we are able to travel at close to Warp 10, like Captain Jun-Luc Picard’s Enterprise, the NCC 1701D. How long would it take us to travel to the nearest alien civilisations? The answer is truly depressing. Even Planet Vulcan, home of Mr Spock, would be around two and a half days at MAXIMUM Warp. If the nearest civilisation were at 10000 light years distance, the Enterprise 1701D would take around 5 years at maximum Warp to reach it, even if Chief O’Brien let him run the engines that hard. Even if we were to develop a Warp drive, nearby extra-terrestrial civilisations are still going to be a long way away and will require journey times of years or decades to reach them. It is hard to imagine that even nearby extra-terrestrial civilisations are going to invest the time and effort to visit us, even if they know that we are here and have starships that are at the limits of our imagination… let alone if they are limited to what we can actually achieve with conceivable future technology. This is just one more reason why we should look for terrestrial explanations first for UAPs.