Monday, January 21, 2008

Why astronomers don't believe in alien UFOs

Image © 1996 Warner Bros.

In the past couple of weeks, there have been many newspaper stories about UFO sightings in western Texas. Larry King even had a segment about the sightings.

Do I think the people of Stephenville saw something they couldn't identify at night? Yes. Do I think they saw an alien spacecraft? Absolutely not. Does this make me part of a giant government conspiracy, or a closed-minded, smarter-than-thou so-called "expert," or an ignorant, evidence-dissing idiot? No.

First, let me say that I suspect that there is life out there in the Universe somewhere. And, like Agent Mulder of television's The X-Files, I want to believe that there is alien intelligence that deigns to contact us humans. But I've never seen any evidence that leads me to suspect that there are space aliens among us.

I can't possibly present a list of all the reasons why I don't believe that people have seen alien spacecraft UFOs. There are a lot, and the reasons vary depending on the circumstances. Let me highlight a few (and note that these are just a few, and that my explanations are not detailed for each reason -- I don't have enough space).

  1. Our eyes play tricks on us. Our eyes and the brain are incredible image processing machines. In a few seconds, we can gather more information from a brief glimpse at a scene than a robot could given hours of time. We had to develop this, or our ancestors would have been eaten by lions and tigers and bears hundreds of thousands of years ago. But our brains and eyes are tuned to exploring our immediate surroundings -- finding friends and foes, determining what we can eat and what may be trying to eat us, that sort of thing. We aren't used to looking and understanding the sky. Given enough time, we can interpret and understand what we see, but even so, we (and I include myself) often get it wrong on first impressions. And when there is something out of the ordinary (like a very bright star near the horizon, or a bright planet, or an airplane or satellite), most people (again, myself included) will get it wrong unless they are making a concerted effort to understand what they are seeing.
  2. Space travel is amazingly difficult. Since humans have traveled to the moon, and since we've sent probes to the far reaches of our Solar System, we tend to underestimate how big and how hostile the Universe really is. And, though there may be physics we haven't yet discovered that allows us to travel safely among stars, as of now we don't see any evidence that such physics exists. It is true that it is poor reasoning to say that the absence of evidence of advanced physics means that it doesn't exist, but it is equally poor reasoning to say that the absence of evidence of advanced physics means that it is likely to exist.
  3. The government can't keep a secret. Government cover-ups are a commonly-quoted excuse for the lack of proof of space aliens. But our government, as big and scary as it can be, can't hide secrets from us for very long. Even big secrets, like forged documents used to justify a war, telephone wiretapping, or Stealth aircraft technology, leak to the public long before the government would like.

    In fact, the government may have a good reason to encourage alien spacecraft stories. If several UFO sightings are really secret test aircraft, keeping people barking up the tree of alien spacecraft would help to preserve the secrecy of the aircraft programs.

So, what would it take for me to believe that a UFO is a likely alien spacecraft? It would take data. Hard, incontrovertible data. What does this mean? Well, a person reporting that an object was "about a thousand feet up in the sky" is almost certainly wrong -- people are horrible judges of vertical distance. But, if you had multiple detailed reports of the exact same object (such as one person saying, "I saw the object while sitting eight feet to the west of the maple tree in my front yard, and it was 16 degrees above the horizon, 78 degrees east of due north, moving on a heading of 162 degrees at a speed of 1.6 degrees per second, and the time was 8:16:35 pm", and another person with a similarly detailed report at the same time from a different location), it is possible to determine the true altitude, heading, and speed of an object. But these reports have to be at least as detailed as the report above, or else any such calculations are meaningless.

Here is where videotape can be handy, but the video has to be of superb quality, with time stamps accurate to a fraction of second, visible landmarks, and, preferably, stars visible in the sky. You should be saying to yourself, "but nobody has that kind of detail!" And you are right -- this is why eyewitness reports, even from very astute observers, are unable to prove many of the "miraculous" actions of supposed alien UFOs -- tremendous speed, strange accelerations, and so on. With multiple simultaneous observations, one can use trigonometry to determine exactly how high and fast an object is moving -- it's even possible to get the orbits of satellites this way!

But these observations are not impossible. A NASA campaign to research the Aurigid meteor shower used accurate video cameras on two airplanes to watch the meteor shower, allowing them to determine accurate positions, altitudes, and speeds of meteors. Accurate reports and videos of a fireball (a very bright meteor) in 1992 that hit a car near Peekskill, New York allowed the orbit of the meteor around the sun to be determined. Amateur astronomers use synchronized video cameras to image asteroids passing in front of faint stars, allowing them to determine the size and shape of asteroids. But the fact remains that almost all video taken of UFOs is not of sufficient quality to do the necessary analysis.

I'll end with a true story of some "UFO" video that I had the chance to view. It was taken by a news crew in Santa Cruz, California, who heard a report of a UFO, and took video over 15 minutes showing the "spacecraft" to slowly settle into the ocean. The cameras had accurate timestamps, and from their vantage point I could tell both exactly where the camera had been placed and what direction it was looking. I then went to a planetarium program, entered the date, time, and location of the cameras, and saw that they had a very nice video of the planet Venus setting in the western sky. The news people were disappointed, and even a bit upset that I didn't agree it was an alien spacecraft landing in the Pacific Ocean. But they should have been happy, because we were able to determine exactly what they had seen. And that is the type of evidence that alien spacecraft would need.

Carl Sagan said, "Extraordinary claims require extraordinary evidence." To be safe, scientists always approach a phenomenon from the negative side -- assume something doesn't exist, and wait for it to be proven to exist. A mountain of marginal evidence (typical UFO sightings) doesn't meet the burden of proof. The evidence that will be necessary to get scientists to take alien spacecraft claims must be exquisite and incontrovertible. I wouldn't trust my own eyes as evidence.


  1. I respect your opinion, as it is a very confusing (and interesting) debate. However, I'd like to recommend two pieces of information to anyone who has second-thoughts, or who simply doesn't believe in the subject. The first piece, a book entitled "U.F.O.'s Are Real: Extraterrestrial Encounters Documented by the U.S. Government", by Sergeant Clifford E. Stone, can be found on It's a truly fascinating read, and will shock many of you. The second (and solid "evidence", in my opinion) is a real video which was taken in Florida, back in 2005. I can't guarantee that an "alien" was in the driver's seat of this vehicle, but this video has convinced many non-believers. As the author has pointed out (and as you'll find on this video), space travel is extremely difficult. But with the Figure 8's this thing is doing, I'm sure that U.F.O.'s are far more technological than we could ever realize.

  2. "Astromers don't believe in alien UFOs" (aka the ET hypothesis)
    "Astronomers don't see UFOs"
    are both common memes often repeated by people who haven't done adequate research.
    Have you heard of Clyde Tombaugh?
    Have you read what he said about UFOs?
    I'm have to wonder if its just ignorance on your part - or if you deliberately failed to mention any astronomers who have seen &/or discussed UFOs (& the ET Hypothesis) seriously.
    Have you tried Google? It might be a good idea to enter a search phrae like :asronomers, ufos - before you write a blog on the subject.

  3. Here are a couple links if you are still having problems finding information on "Astronomers & UFOs":
    (see section five)

  4. Anonymous8:29 PM

    ..."are both common memes often repeated by people who haven't done adequate research."

    While I can't speak for the author of this blog, I'm fairly certain the phrase was used as a generalization. As a generalization there will always be exceptions, and those do not invalidate the generalization itself.

    This very thing helps illustrate the difference between an analytical healthy skeptic and someone who just wants to believe. I've seen an amazing sight in the sky myself. I was completely convinced that what I saw was inside the Earth's atmosphere and flying around. There was no way I would initially accept that a planet or star was the source of light I witnessed. Yet with some digging around followed by a second morning of viewing the same patch of sky, I found that what I observed was the star Sirius. This was a strong personal experience that hammered home the concept of unreliable witnesses. But unlike the average UFO believer, rather than be disappointed in what I saw, I marvelled that something I've seen hundreds of times appeared so amazing under the right circumstances.

    There are plenty of marvels in the sky without the need to believe these things are more than they actually are. We have incontrovertible proof of so many wonders, but alien spacecraft is not one of them or this discussion wouldn't be taking place. I won't say I'm 100% convinced we will never find such proof, but I do feel it is foolish to place such stong belief in their existence based on the rather flimsy evidence one finds in the average UFO report.

  5. Anonymous9:33 PM

    For what it's worth, I am a firm believer in UFO's. I've seen one. When I was a teenager, I saw something very strange in the night sky. I described it to some friends (we were out camping at the time) and they were skeptical. However the next day's newspaper reported the same account witnessed by others. All I saw was an inexplicable light, and movement of that light in the sky.

    It was caused by something, so lets call that something an object. It was up in the sky so I'll say it was flying. I certainly have no idea what it was, and as far as I know, no one else did either so it's unidentified. It was an unidentified flying object (UFO).

    What I am absolutely certain of is that there is a perfectly rational explanation that doesn't involve space craft from distant places. The fact that I can't explain what I saw does not entitle me, or anyone else, to assume extra-terrestrial involvement.

    Personally, I'll accept that there likely are intelligent civilizations out there, most likely many of them. I also accept that they are likely so far apart (millions or billions of light-years) that the chances of us ever bumping into one another are, well... pretty much zero.

  6. Anonymous8:31 PM

    To travel between stars will take the gift of immortality and incorruptability, in the resurrection. This is the only way to protect against TWo most volatile enemies: 1. radiation. 2. Micrometeorites. Any other "thing" traveling around violating the "LAWS" of physics,is 'sinful', and therefore fits ALL the definitions of what an ('interdeminitional" being?) demon is. They are not physical as we believe, but incorporeal beings. They are under prohibitions by God, but can "project" their delusions upon our material world like a projector does light and images against a movie screen. Anything physical does not, because it cannoty break the laws of physics. UFOs break the "laws" of physics. Thus, UFOs are not physical; and neither are the "things" occupying them, if they are hollow. And I doubt that. I think people's brains are more hollow who believe in such nonsense.