ASTR 1210 (O'Connell) Study Guide 18

---

Poster from a 1957 movie featuring all the earmarks of the classic invasion
drama: flying saucers, death rays, and big-headed, bug-eyed aliens
with triangular faces and a penchant for scantily-clad women.

Because it fixes the ultimate scope of the human universe by exploring the largest scales of space and time, astronomy has always had a strong hold on the imagination. Inevitably, discoveries about stars and planets raise questions about life on other worlds.

Speculation about inhabitants of other planets goes almost as far back in history as there are written records, but it was given new impetus after 1550 by the enormous Copernican/Galilean universe, which was potentially infinite in extent and possibly filled with planets like the Earth. This idea was championed by early post-Copernican writers like Thomas Digges and Giordano Bruno.

Until the end of the 19th century, aliens were usually imagined to be enlightened and benevolent creatures. Since then, the popular concept of aliens has darkened considerably. As the movie poster above vividly testifies, they are now typically viewed as menacing (the Steven Spielberg cutie-pie creations in "ET" and "Close Encounters of the Third Kind" notwithstanding).

The change can be traced to a single novel, stimulated in turn by astronomers' studies of the planet Mars. This lecture discusses the novel and one of its main legacies: a remarkably widespread form of mild mass hysteria, the "UFO" phenomenon. "UFO's" lead us to return to the subject of the standards of scientific evidence and interpretation of observations.

Martians rule the British Navy in "War of the Worlds"

A. The War of the Worlds

Claims of some astronomers (1875+) to have detected Martian "canals" and Percival Lowell's widely circulated arguments that these were artificial and were built by civilizations on Mars provoked intense public interest in the possibility of extraterrestrial life.

Intrigued by the notion of life on Mars, the English writer H.G. Wells -- already a well-known author of "scientific romances" like The Time Machine and The Invisible Man -- conceived the novel The War of the Worlds (1898).

• This was the first hostile alien invasion story.
  
• Wells was one of the first novelists to understand clearly the wider implications of scientific discoveries.

• In WoW, he combines the vast Copernican cosmos (no longer centered on the Earth or mankind's welfare and potentially rife with advanced lifeforms) with Darwinian evolution, which implies competition for scarce resources and "survival of the fittest."

• The inevitable implication of these two ideas is interplanetary migration, a concept Wells first introduced in his novel. The evolutionary imperative means that migration can take the form of a hostile invasion.
  Recall that the Mars envisioned by Lowell was a desert planet, where the inhabitants were in a desperate struggle for survival. In Wells' novel, the Martians, with "intellects vast and cool and unsympathetic, regarded this Earth with envious eyes, and slowly and surely drew their plans against us."

• More generally, Wells recognizes that the extraterrestrial environment is not benign for humans:
  "We can never anticipate the unseen good or evil that may come upon us suddenly out of space."
  Modern astronomers would certainly agree with that statement, though they might doubt the likelihood of "unseen good." Public fascination with aliens notwithstanding, the modern assessment is that realistic threats from advanced alien lifeforms are a much more remote possibility than those from our natural cosmic environment: asteroid and comet impacts, energetic outbursts on the sun, supernovae and other stellar explosions, etc.

• Wells also incorporated ecological ideas in the form of the symbiotic relationship between advanced lifeforms and microorganisms and the fact that this will differ from planet to planet. The humans are powerless in the face of Martian military technology, but [spoiler alert] terrestrial bacteria prove fatal to the Martians and save mankind in the end.

• Wells was primarily a social commentator, and the novel constitutes an incisive critique of modern life: the evils of colonialism, now visited ruthlessly upon the British Empire --- the world's largest --- by the Martians; the fragility of civilization (e.g. the panicky evacuation of London; the inversion of the food chain in a matter of hours, with humans becoming Martian dinners); the shallowness of religion and conventional moral judgements (e.g. the curate).
  Wells' portrayal of the rapid collapse of civilization may have been exaggerated for dramatic effect, but it is not that far off the mark. Even today, a disruption in the electrical grid (see Study Guide 9) and food delivery would begin to have drastic effects after only a week. Almost literally, our technological civilization is only a few days thick.

• Wells recognized (and implicitly warned about) the rapid pace of (human) technological development and its implications for society
  • The military technology of Wells' Martians is utterly overwhelming yet is not even 100 years more advanced than their human opponents'. The US military today could easily handle the Martians in the story. (But compare this measly one century Martian advantage to the millions of years of development that are likely to separate us from any real space-faring aliens.)

  • Wells was adept at seeing where technology was leading. His fictional Martian fighting machines (tanks) and poison gas materialized as key weaponry in World War I, 15 years later. In later works, Wells predicted the military importance of aircraft (which the WoW Martians had in only prototype form) and described for the first time the devastation of an atomic war --- in 1914, a quarter century before practical atomic weapons were even conceived.

  • The larger implication is that technology is rapidly transforming human cultures, and the consequences are not easy to predict. We already discussed the ways in which new technology can "boomerang" in Study Guide 9.

  • Wells was not optimistic that mankind would take the lessons in his writings to heart. His self-epitaph: "I told you so. You damned fools!"

Legacy

• The War of the Worlds was a watershed creation. It echoed, at the end of the 19th century, the dark warning about technology in Mary Shelley's Frankenstein from its beginning. It struck a tremendous resonance in the popular imagination. It has been in continuous print for 120 years and became the archetype for a vast body of later science fiction and other speculative literature.

• Translations of the story to the panic-inducing 1938 Halloween eve radio broadcast (by Orson Welles, no relation) and the first special-effects-heavy invasion film (1953) heralded a huge wave of radio, television, and movie invasion stories (ca. 1940 to the present), a promo for one of which is shown below.

• Today, aliens are a staple of modern popular culture. The media are so saturated with them that we think it is normal and amusing, rather than surpassingly strange, if, as in Calvin & Hobbes, third graders spend hours happily imagining themselves to be pursued across deep space by hostile aliens.

Intrepid junior scientist David notices something's wrong in the backyard in this comic-book promo for the film "Invaders from Mars," a classic 1950's paranoid fantasy in which his parents and most other adults are taken over by the invaders, except for a dashing astronomer and a beautiful doctor, who help David save the world---or do they?

B. UFO'S and the Limits of Science

Another lasting legacy of Lowell, Wells, and a vast amount of speculation by others is the "UFO" controversy. What started as a legitimate (if mistaken) interpretation of astronomical observations and a brilliant piece of fiction has become a worldwide mini-industry, with a multitude of committed believers and its own media and interest groups, not to mention millions of web sites. It is based on the belief that the Earth is under continuous surveillance by alien spacecraft and that there is a government conspiracy to cover this up.

"UFO" is an abbreviation for "Unidentified Flying Object"

• The popular understanding of a "UFO" is something unfamiliar in the sky that looks artificial, not natural. If no further inferences were drawn, this would stand as a reasonable characterization of an observation. However, encouraged by widespread publicity, especially in the less discriminating tabloid media, many people are inclined to assume that UFO's are always alien spacecraft.

• The scientific view is that, just as the description itself implies, without further investigation the "object" is not identified, whether as a spacecraft or an entirely normal (natural or human) phenomenon, regardless of how strange it might appear.

UFO reports

Who reports UFO's?

• Reports are overwhelmingly from untrained observers. Only a minority come from professionals (pilots, military, police).

• Very few are from scientists, especially astronomers or others familiar with sky phenomena.

• Reports are predominantly visual sightings, without a permanent record or objective data (e.g. radar, photographs, videos) of any kind

UFO reports have many historical precedents.

• Apart from the familiar phenomena in the sky, many of which we have already discussed, there have always been reports of unusual, transient features.

• Records of "strange things" seen in the sky extend back as far as 400 BC. They include unusual lights or color displays, sounds, moving objects, and (in the 19th century) reports of "airships." Almost none were subjected to critical scientific analysis until after 1900.
  Most of these undoubtedly originated from real, if uncommon, phenomena that we now understand well, like light scattering in the atmosphere, rare cloud types, aurorae, comets, and meteoroids, which were misperceived as supernatural or anomalous events.

The modern era of UFO's began in June 1947 with widespread media coverage of a report that civilian pilot Kenneth Arnold (at right) had seen a formation of "saucer-like" aircraft flying at speeds over 1000 mph near Mt. Rainier.

• Publicity over Arnold's sighting led to an intense "flap" of "flying saucer" reports over the next several years.
  A telling irony is that almost all of these reports involved flying disks or saucers even though Arnold's original description was that the strange objects looked like swept-wing aircraft (see the picture at the right and this Arnold sketch) and were like saucers not in their shape but only in that they "flew erratic, like a saucer if you skip it across the water." Newspaper accounts of the Arnold incident compressed the description into "saucer-like objects," so the public assumed the craft were round and disk-like. The erroneous media description clearly strongly shaped the subsequent reports.
  Interest in the Arnold report was amplified by building cold-war tensions with the USSR. In fact, the primary concern of the government at the time was that the "saucers" might have been experimental Soviet aircraft (having somehow managed to get halfway across the state of Washington without being detected).
  The spate of post-Arnold reports included the now-infamous Roswell, NM case. This was a low-profile incident at the time but has more recently been promoted as a classic event because pieces of a supposedly-crashed alien spacecraft were reported to have been recovered.

• 1947-today: There have been tens of thousands of reports of strange flying objects, often in similarly concentrated flaps, triggering a number of US Air Force and other government investigations. Since the 1970's, there have also been reports of (temporary) human abductions by alien spacecraft. In the last five years, several videos of strange phenomena recorded on US military sensor systems have received wide media coverage.

Anomalistic phenomena

UFO's are an example of an anomalistic phenomenon: something apparently inconsistent with the prevailing scientific consensus but only marginally documented.

Where do anomalistic phenomena fit into the scientific context? And under what circumstances should we accept them as expanding the boundaries or limits of conventional or mainstream science?

Consider mainstream science first:

Our scientific understanding of many aspects of the natural world is truly profound, as it should be after hundreds of years of concentrated effort. It encompasses almost everything we encounter in everyday life.
If our fundamental assumptions about the physical or biological world were seriously flawed, then, as discussed in Study Guide 9, much of the technology we depend on in everyday life, including medicine, would simply not work. For instance, our deep understanding of electromagnetism is tested millions of times each second in every electronic device on Earth.
Our understanding of these phenomena is based on a vast repository of evidence, which is continually sifted for quality and checked against new pieces of evidence. There are currently over 2 million professional scientific papers published each year across all fields. Not all of these are right, and only a fraction are truly important. But the edifice of high quality scientific information is expanding rapidly.

Nonetheless, at any time, there are many well-documented phenomena that scientists do not adequately understand.
• Examples from the past: stars; motions of the planets; the origin of the elements; the Bubonic Plague; the basis of genetics. All of these "problems" have been solved.

• Examples from the present: "dark" matter and energy in the cosmos; "junk" DNA; Alzheimer's disease; the nature of human consciousness.

These unsolved problems represent the current boundaries of scientific understanding. They are what drive scientific curiosity and what active scientists work to explain.
Young scientists, especially, like to work on such problems. There are strong incentives to discover new phenomena or interpretations that countervail the accepted wisdom. That is how young people can make careers in science. However, they always have the obligation to demonstrate, usually by very hard work, the validity of new views to a (properly) skeptical audience.

The first steps in scientific understanding are to identify a phenomenon and to carefully establish its properties. Interpretation cannot begin until it can be placed in the rich context of what we already know.

Varieties of pseudo-science

Pseudo-Science

In contrast to the subjects of mainstream science, "anomalistic" phenomena are not even established as real. There is insufficient objective, controlled evidence to show that the claimed phenomena even exist, let alone imply something beyond the capacity of normal science to explain.

Most of the subjects of "pseudo-science" fall in this anomalistic category: astrology, ESP (extra-sensory perception), telekinesis (moving objects with mind power), ghosts, psychic forecasts, cryptozoology, the Bermuda Triangle, Atlantis and other suppposed ancient super-civilizations. Also much "alternative" medicine.
We briefly described pseudo-scientific investigations in Study Guide 1. They apply only some, not all, of the established methods of science. They have not been validated by mainstream science. Hallmarks of pseudo-science include:
Uncritical acceptance of poorly documented phenomena; lack of experiments or inadequate experimental controls; investigator bias; inexperienced or unreliable observers; logical fallicies; statistical manipulation; non-repeatability; often self-deception or delusion; often for-profit publicity/entertainment; sometimes deliberate fraud.
One example: we know from tens of thousands of experiments that penicillin kills certain types of dangerous bacteria. But no one has ever convincingly been shown to be able to read someone else's mind.

Crucially, most pseudo-scientific claims are inconsistent with the enormous body of established scientific facts. For instance, foreseeing the future contradicts the verified principles of special relativity.

Because of the doubtful reality of anomalistic phenomena, mainstream scientists are reluctant to invest much energy in pursuing them until the accumulated evidence passes some threshold of plausibility.
Nonetheless, you will find almost as many books on pseudoscience in a typical American bookstore as on science itself. They sell well because of their emotional appeal and because most people do not know how difficult it can be to validate scientific ideas or how to apply suspended judgement (skepticism, see Study Guide 1) to new propositions.

Most pseudo-science is harmless, except for the sloppy thinking and miseducation it encourages. But some pseudo-science poses tangible threats to you and society. For example:

Fraudulent or ineffective "alternative" health-care (such as homeopathy, in which the active therapeutic ingredients are diluted to the point where not a single molecule remains).
As some critics of pseudo-science put it: "alternate medicine" that actually works is called "medicine."

Rejection of proven beneficial medical protocols or treatments, like vaccines, because of personal, political, or religious agendas. These were especially harmful, and resulted in the unnecessary deaths of hundreds of thousands of people in the US alone, during the COVID-19 pandemic.
False criminal prosecutions (murder, child abuse, satanic rituals, etc.) based on erroneous psychotherapy (e.g. "suppressed" memories "recovered" by hypnosis).

The role of credulity

The widespread interest of the public in anomalistic phenomena is fueled by human credulity: the proclivity to believe things in the absence of good evidence because they appeal to personal prejudices. This is a form of what psychologists call confirmation bias.

Erroneous beliefs may offer some kind of reward: they may promise excitement and drama; may offer power, comfort, or money; may be reassuring; may support populist beliefs; or may fulfill personal wishes. The universe of wishes may not be larger than the real universe, but it exercises much more powerful attraction for people.
Alternatively, on the dark side, they may present a threat that conforms to existing prejudices. Peoples' erroneous beliefs about a perceived, but unsubstantiated, threat are often amplified by crowd psychology, leading to various forms of aberrant collective behavior in the form of a fear or anger reflex.
This kind of collective credulity finds expression in some unpleasant forms: financial bubbles, imaginary maladies, persecutions, destructive political movements, and mob violence -- even genocide.
If you want obvious contemporary examples, consider the rapid spread of misinformation during the recent COVID-19 pandemic and the ever more prominent "viral swarming" that regularly occurs on modern social media.
In its more extreme forms, aberrant collective behavior becomes mass hysteria, a well documented affliction, some episodes of which are described here.
An invaluable handbook of human credulity and mass hysteria throughout history is the compendium Extraordinary Popular Delusions and the Madness of Crowds by Charles Mackay, described further below.

Scientific standards

How should UFO reports be interpreted in a scientific context? How much credence should be given to the extraterrestrial hypothesis?

• First, recall the important criteria for validation of scientific claims (see Study Guide 1):
  • Quality of the objective empirical evidence

  • Consistency with known science

  • Repeatability and validation by independent investigators and methods

  • Simplicity: the principle known as Occam's Razor leads us to choose the interpretation with the fewest additional assumptions.

• "Extraordinary claims demand extraordinary evidence." (Carl Sagan)
  Empirical validation is essential before we can accept the extraterrestrial UFO hypothesis --- but using only the highest standards. Because of its importance, if true, we must require unimpeachable evidence. According to Occam's Razor, we must eliminate all ordinary explanations before we appeal to extraordinary ones.

• Data reliability is crucial:
  • Unfortunately, and contrary to widespread belief, "eyewitness" accounts are often faulty, especially from untrained observers.
    • Reams of courtroom records in routine criminal cases vividly attest that eyewitness testimony is often greatly inferior to circumstantial evidence. See "On Being Certain" by R. Burton.

    • We have already seen, in the case of the "canals on Mars", how even trained scientists can be misled by visual observations made under marginal conditions.
      From Guide 16: There is a great temptation to overinterpret marginal data and to try to force them to conform to preconceived ideas. This is an important factor in many areas of mainstream as well as "anomalous" science. Good scientists will resist this. They will honestly assess the uncertainties in the situation and will withhold judgement until the evidence improves.

    • It is hard to judge visually the distance, speed, & motion of objects in the sky---even for experienced observers like airline pilots. Since inferred speed depends on inferred distance, claims of abnormally high velocities are doubtful unless distance is well established.

    • It is hard to distinguish between the motion of an object in the sky and the observer's own motion. If the observer is themself moving, a "parallax" effect (see Guide 6) can make stationary or smoothly moving distant objects appear to move erratically in unphysical ways with respect to the observer's surroundings.

    • Any transient phenomenon is hard to assess well.

  • For these reasons, objective evidence is strongly preferred, based on radar, imaging, or physical samples, for example.
    • But there has been precious little high quality, objective evidence concerning UFO's in the last 70 years.

    • "Have you noticed since everyone has a camcorder these days no one talks about seeing UFO's anymore?" Car Talk, Sept 2002. Yes, it isn't helpful to the alien enthusiasts that even though there are now billions of capable video cameras (e.g. in cell phones) spread across the face of the Earth, there are no better video recordings of alien spacecraft than there were 50 years ago. This is despite the proven ability of people to capture sudden, unusual, brief events (airplane crashes, for instance). The alien pilots are a lot more bashful than the Los Angeles Police Department.

• A sighting of an "unidentified" object in the sky doesn't demonstrate the existence of an anomalistic phenomenon. It simply creates a list of possibilities for its explanation.
  • That list must include the full range of possible mainstream scientific explanations, including a mistake or wishful thinking. The list must be refined using our full cumulative understanding of nature and by the empirical probability of each explanation.

  • Something that looks strange to an untrained observer may have a perfectly ordinary explanation. Even if not, that doesn't mean the explanation is beyond conventional science.

  • Even the word "flying" may be prejudicial in a UFO report. What are often called UFO's aren't flying at all. They are in the sky, but they may be outside the Earth's atmosphere: stars, planets, satellites.

Scientific assessment of UFO reports

• There have been many UFO reports, but thousands of badly documented cases are less useful than a single, thoroughly documented case.
  Only a minority involve photographs. We will show a number of UFO photos in class -- all of which look very strange -- and consider the possible explanations of them.

• After investigation, it turns out that 90-95% of UFO reports (including the ones shown in class) are clearly misperceived natural or human phenomena: airplanes, balloons, planets, stars, clouds, birds, unusual atmospheric phenomena (e.g. ice crystal scattering producing sundogs), rocket launches, flares, etc.
  Click here to see a remarkable collection of the unusual natural sky phenomena that could be mistaken for spacecraft.

• The most commonly reported "UFO" other than airplanes is Venus. It can be dazzlingly white and astonishingly bright, making people think it's close by, when in reality it is millions of miles away. "Seeing" effects in Earth's atmosphere can cause it (and other planets and bright stars) to appear to pulsate, wobble, or change color.
  Viewed from a moving vehicle, like a car, celestial objects like Venus can seem to be moving at high speed -- even "chasing" you -- because they stay in a fixed position in the sky while the local terrain moves backwards quickly.

• Some of the most surprising natural features that are mistaken for alien spacecraft are lenticular clouds, which can form when moist air flow is disrupted by obstructions. These have a natural lens-like or saucer-like shape and often feature multiple layers that look like aeronautical structures. A sample of lenticular cloud images is shown below, and more are collected here.
  
• The 5-10% of reports without obvious explanations mostly have insufficient information for analysis. However, a number of more complete cases have been pursued carefully and have turned up no convincing evidence of extraterrestrial craft. (E.g. see the Philip Klass book UFO's Explained, cited below.)

• Some famous cases were deliberate frauds/hoaxes. There are many more cases of obvious self-delusion or irresponsible hype.
  The Roswell incident was an egregious example of the latter, in which a few fragments of a crashed, classified US high-altitude military balloon -- intended to survey for sonic evidence of Soviet nuclear tests in the aftermath of World War II -- were touted as irrefutable evidence of an alien spacecraft. The Air Force contributed to the misunderstanding by initially claiming the debris was from a flying saucer -- stupidly thinking that a UFO report would be great cover for a top-secret mission. The pictures of an "alien autopsy" that often accompany discussion of Roswell on the internet are frauds.
  Often, there is a willing suspension of critical faculties by UFO promoters: after all, the UFO industry is comfortably profitable.

• Historical UFO reports are clearly strongly colored by people's prejudices. In the 19th century, reports tended to be of "airships"---i.e. balloons or dirigibles. There were very few "saucer" reports before 1947.

• Many psychological factors are involved (e.g. early flurries of UFO reports coincided with Cold War tensions and widespread fear of a Soviet attack). The UFO "flaps" (clusters of reports) have all the hallmarks of crowd/collective effects. Serious investigators must work hard to separate the mass psychology from whatever reality might lie behind the reports. Overall, the UFO phenomenon shows symptoms of a mild form of mass hysteria.
  
• There has been an overwhelming media influence, especially from film or TV dramas (e.g. at right), on the frequency and especially on the similarity of modern reports.
  Ironically, the similarity is then cited as evidence for the reality of the phenomenon.
  Saucer-like craft had themselves debuted in 1920's science fiction magazines----20 years before people started reporting them in the skies.
  Public impressions of alien spacecraft and aliens themselves are now so strongly driven by fictional media presentations, that it is almost impossible to disentangle reality from prejudice in most reported UFO incidents.

• Belief in UFO's as extraterrestrial can have religious overtones (e.g. the ET's substitute for the second coming of Christ) and has sometimes been linked to explicitly religious activities:
  • The Heaven's Gate suicide cult

  • Scientology, a nouveau religion fabricated by a science-fiction writer and based on the theme of interstellar migration

• Finally, what about the credibility of an almost impenetrable government conspiracy to cover up evidence of alien visitations for the last 70 years?
  Answer that for yourself with three letters: I.N.S.:
  Recent decades have featured an embarrassingly rich tableau of ineptitude and porosity by government agencies. Lest we forget one of the classic cases: the Immigration and Naturalization Service issued welcoming visas to some of the September 11th hijackers 9 months after they had died in the wreckage of their aircraft. Credible evidence of a UFO coverup by the government would have been splashed across the front page of the New York Times decades ago.

  "If the government is covering up knowledge of aliens, they are doing a better job of it than they do at anything else." --- Stephen Hawking

The bottom line is that in 75 years there has not been a single UFO case meeting the conventional standards for scientific validation as a new phenomenon, let alone the higher ones needed to accept an extraterrestrial interpretation.

Military videos and investigations (2004- )

Several extended videos of UFO's taken with US Navy aircraft imaging systems over the period 2004-2019 were released to the public starting in 2017 and generated great interest. These included radar and infrared data. The videos appeared to show strange structures and motions that were beyond the capabilities of known aircraft.

The Director of National Intelligence prepared a confidential summary of these and other cases (now relabeled "Unidentified Anomalous Phenomena" rather than "UFO's") for the US government and released a brief unclassified version to the public in June 2021. This was not very helpful. It did not reach firm conclusions about most of the 144 incidents reported but recommended in view of possible national security concerns that better reporting protocols were needed.

The combat systems involved here employ sensors and complicated processing electronics and software that aren't necessarily well designed for determining the intrinsic properties of the targets detected. They are vulnerable to various kinds of artifacts and anomalies. Researcher Mick West has analyzed the three most widely viewed videos and found reasonable explanations for them that don't involve adversarial or extraterrestrial aircraft, rather ordinary aircraft or balloons viewed from a rapidly moving platform and camera equipment that can produce artificial motions in the images.

Because of the intense revived interest in "UAP's," NASA convened a special advisory committee to establish an empirical agenda for investigating them in 2022.

In March 2024, the Defense Department released a more strongly-worded report stating unequivocally that there was no evidence in its records or studies it sponsored that UAPs are extraterrestrial spacecraft. As summarized by the Washington Post, "They were 'ordinary objects and phenomena and the result of misidentification,' sometimes by well-meaning witnesses who thought they had spotted something otherworldly." The Post itself interviewed some of the people who claimed they knew about captured alien spacecraft and reverse-engineering attempts by the US military but stated, "[We] chose not to publish these accounts because the individuals provided no evidence to corroborate their claims. Their information was almost exclusively based on second- or third-hand statements, usually from people the interviewees declined to identify."

Needless to say, coming so late (75 years) into the modern UFO era, this report will not be warmly greeted by the UFO enthusiasts and conspiracy buffs.

Watching the sky

Here's a simple reality check if you see something strange in the night sky:

1. Watch for 5 minutes. Is the "UFO" stationary with respect to the stars? If yes, then it's probably a celestial object, a minimum of many millions of miles from Earth.
   
2. Is it within about 40^o of the western horizon (near sunset) or eastern horizon (near sunrise)?
   
3. Is it in a Zodiacal constellation?
   If yes to all three, then it's probably Venus.
   Jupiter is also a commonly-reported "UFO," but it need not meet criterion (2) here.

4. If it's a slowly moving light or cluster of lights, it's most likely an aircraft. Aircraft normally move across the sky steadily in straight lines from horizon to horizon. Lights are normally white and blinking, although they can also be steady and sometimes red or green. Higher altitude aircraft may not make any detectable sound. As they approach their destination airport, aircraft will turn on very bright landing lights, which will definitely look strange if you are unused to them.
   Ordinary spacecraft, including the International Space Station, can occasionally be seen for an hour of so after sunset or before sunrise, when they are still out of Earth's shadow at their altitude. They will move silently in straight-line paths. Bright temporary flares or "glints" can occur as sunlight reflects from the surfaces of some satellites.
   The Heavens Above website specializes in tracking satellites and satellite flares and can predict their appearance for any place on the globe.

For help in placing UFO reports in context, you might refer to the guides published by the Center for Inquiry and their list of seven tips for keeping reports grounded in reality.

Conclusions:

• There is a very low probability that UFO's represent a new or important natural phenomenon.

• There is a near-zero probability of alien spacecraft being involved.

• That is the scientific assessment today. Of course, the evidence could improve dramatically tomorrow. The scientific consensus has sometimes rejected the right ideas for the wrong reasons (e.g. meteorites, continental drift).

• But wait for the evidence.

---

Reading for this lecture:

H. G. Wells War of the Worlds (an electronic version from Project Gutenberg is here.)
Study Guide 18
Optional reading: Philip J. Klass UFO's Explained (Clemons Library, TL 789.K56 1975)
Optional reading: Curtis Peebles Watch the Skies! A Chronicle of the Flying Saucer Myth (Clemons Library TL789.3 .P44 1994).

Reading for next lecture:

Study Guide 19
Bennett textbook, Chapter 10.

---

Web links:

Mars in Popular Literature
Radio Broadcast of "The War of the Worlds" (Orson Welles, 1938)

Mr. Welles and Mass Delusion (Dorothy Thompson, 1938)

War of the Worlds, The Musical(!)
The Dr. Zeus collection of "War of the Worlds" book covers. Trace the evolving visualizations of one of the most re-published novels in history.
Electronic versions of other H. G. Wells stories
War of the Worlds. 2005 Steven Spielberg-Tom Cruise blockbuster film version.
Wikipedia article on the 2005 film
An appreciation of Invaders From Mars (1953 film)
Without Warning, an interesting 1994 TV invasion movie that reproduces, if clumsily, the "live broadcast" atmosphere of the Orson Welles' 1938 radio program in updated form, employing asteroid impacts (see Guide 22) as the invaders' weapon.
Life in the Universe (Study Guide 23)
Skepticism and Critical Thinking Resources
Extraordinary Popular Delusions and the Madness of Crowds by Charles Mackay (1841).
Famous compendium of cases of mass hysteria, collective delusions, economic mania, and magnificent scams. You will immediately realize that some of these are amazingly similar to the dot-com, toxic mortgage, and cryptocurrency bubbles of more recent years. Human frailties have not diminished much in the last 2000 years, and this book provides vivid documentation. Required reading for anyone planning a career in social science, politics, law, marketing, or business. You can find a recent review here.

The Center for Inquiry and its magazine, The Skeptical Inquirer.
The Skeptics' Guide to the Universe: How to Know What's Really Real in a World Increasingly Full of Fake by Steven Novella (2018)
Field Guide to Critical Thinking (from Skeptical Inquirer Magazine)
James Randi Educational Foundation (site discussing responses to pseudoscience, including UFO's and faked evidence)
Links to "Skeptical" Resources (Donald Simanek)
Bad Astronomy: An excellent site (by UVa Astronomy grad Phil Plait) on misuse/misunderstanding of science in the media and entertainment.
TEDx Talk on Skepticism (nice 24-minute tour of faith, denialism, and the value of skeptical thinking in our lives by George Hrab)

As of 2023, you can find upwards of 280 million pages(!) on the Web that mention UFO's (up by 50x in 15 years). The vast majority of these will feature uncritical acceptance of the ET hypothesis. Some antidotes:
CfI: Skeptics Remind News Media: Keep UFO Reporting Grounded in Reality
Claims About Alien UFOs: Resources (Andrew Fraknoi)
UFO Skeptic's Page (Robert Sheaffer)
UFO Skeptic Pages (Ian Ridpath)
UFO Misidentifications
The Condon Report (government-sponsored 1968 scientific study of UFO's)
Faking UFO's using NASA satellite data
Air Force Report (1994) on the "Roswell Incident"
Planning the "alien autopsy" coverup (Mitchell & Webb)
The UFO Movie THEY Don't Want You To See (2023 documentary on the scientific assessment of UFO's)

---

Previous Guide

Guide Index

Next Guide

---

Last modified March 2024 by rwo

Artwork here is from War of the Worlds, The Musical and original film posters & promo material. Scan of the cover of the 1993 edition of WoW from Dr. Zeus. Text copyright © 1998-2024 Robert W. O'Connell. All rights reserved. These notes are intended for the private, noncommercial use of students enrolled in Astronomy 1210 at the University of Virginia.