Exposing PseudoAstronomy

July 14, 2012

Some Astronomical Errors at TAM 2012


As some of you know, I’m attending the James Randi Education Foundation’s annual skeptics meeting, “The Amazing Meeting” (TAM) this year for the first time. I’m excited to be here, meeting people I’ve grown to look up to for the past few years, getting thrown a shirt last night by Penn Jillette without even having to flash my moobs, gushing at idols, etc.

That said, in the absolute least bitter/arrogant way possible, and with all due respect, I’ve been amazed at the astronomy (and astronomy-related) mistakes that have made their way into talks at this conference.

Edited to Add (07/20/2012): I put an “Addendum” at the end of the post to explain a bit more about McGaha’s errors.

“Astronomy for Skeptics: Investigating ‘Lights’ in the Sky” Workshop

To be perfectly blunt, James McGaha’s workshop was bad. The workshop as a whole was scattered content-wise, not cohesive, and very little of the workshop focused on the advertised content. Besides this, roughly half of his informational statements were factually wrong.

After calming down after the workshop, I wrote down some of the main errors I remembered. Among them …

McGaha stated that the Maya didn’t have any math, they could only count, and that’s what the Long Count calendar was, just a count. True, that’s what the Long Count was, simply a count of days in multiples of 20 and 18 and 13. But the Maya – while not nearly as sophisticated as modern mathematicians despite what new-agers want to think – had a very complex mathematics system for their time. They could count, yes, but they could do things with those counts, and they could make astronomical predictions spanning hundreds of years with a good understanding of celestial cycles.

Technologically, McGaha claimed that all GPS compasses cannot actually tell direction via GPS, that they have a small magnetometer in them that must be calibrated every time. This may be true for some. Might be true for your cellphone, your tablet, and some GPS stand-alone devices. But I have a nice field GPS. It tells direction in part by simply seeing how I’ve walked the last few steps and thus taking a difference of the latitude and longitude in order to tell what direction I’m going. No calibration required. He also said that if you hold a battery close to it, it will throw the reading off. Um, no.

After he was finished doing demos with a two-inch device to a room of 300 people, he got into some photography stuff. Among many other things, McGaha consistently messed up “pixel scale” and “resolution” as well as focus and depth of field. I’m not going to get too much into the latter because I was busy with something else while he was going over it, but for the former … “pixel scale” is when you say something like how many pixels per unit of measure. Like, each pixel in a photo is 2 inches in real life of the object being imaged. Resolution, on the other hand, is how many pixels are there. A high-resolution photo is saying that it’s something like 26 megapixels versus 1.3. It may be the most out of focus, poorly imaged thing where you can’t separate two broad barn doors, but it’s still high resolution.

Later, McGaha tried to demonstrate the motions of the stars through the sky with some laser pointers. He got it wrong. He also had a graphic in his slide show trying to show how we define the coordinate system on the sky. His diagram was a bit wrong in how the celestial poles are defined (not from your local north/south, but exactly from Earth’s rotational axis projected onto the sky).

Finally, one of the last things that he talked about was how your eye tells color. He stated that your eye cannot figure out the color of a monochromatic light source directly, that it needs a comparison source to tell. That’s wrong. He also said that with a monochromatic light source, if you change the intensity, your eye will perceive a different color. Um, no. Take a 5mW and 25mW green laser pointer and your eye will see the same color, not different ones.

Ben Radford and 2012

This was a talk I went to because I wanted to see how a non-astronomer skeptic approached the topic. His half-hour talk was basically a run-down of previous failed doomsday predictions, the classes of doomsday prophetic ideas, some humorous clips and quotes from proponents of this particular one, and then a very very cursory (like, 5 minutes or so) overview of how this got started and the Mayan calendar.

There honestly (and unfortunately) wasn’t much meat to the talk, but when he did talk about the Maya, he made some mistakes. One was saying that the Long Count does end this year. This is wrong. It ends one of the 5125 parts of its cycle, but it ticks over to the next “one up digit” of it (like going from 9999 to 10,000). Another mistake was that Ben appeared not to know that this “next tick” may not be this year. It’s based on a correlation that may be wrong, and likely is based on the latest research. It could be easily off by any multiple of 52 years.

A third error in Ben’s talk was his statement that the “end date” only comes from one Mayan inscription. This was correct until a few months ago. Recently, archaeologists discovered another inscription from very roughly 1000 years ago that referred to it. Not a major issue, but it negated (or seriously minimized) his point, and for someone who is an investigator putting together a talk for a major skeptics conference, I was somewhat disappointed.

Ben also seemed to not realize that this meme did not start with recent movies and and books. It has a definite starting point in the 70s and a bit earlier with a few specific people (such as José Argüellas or John Major Jenkins or Zecharia Sitchen). He held up recent books, not the ones that started it.

Oh, and Ben, Tabasco sauce is not made in Mexico. It’s “produced by US-based McIlhenny Company of Avery Island, Louisiana” — check Wikipedia.

I was okay with Ben not doing astronomy nor a summary of what people thought would happen. I was okay with the direction of his talk because, as I said, I wanted to see how a non-astronomer approached it. But factual errors and a lack of research from someone like Ben Radford was disappointing.

Final Thoughts

I realize this post may have sounded a bit annoyed and crotchety. But this is a skeptics conference where we’re pointing out where OTHER people are making mistakes. We should not be making our own.


Several people have asked me how McGaha got the motions of the sky wrong. Here’s a short, abridged list:

  • He didn’t know which way was north in the room even though he had just been demonstrating compasses for the past ten minutes.
  • Second, he was trying to show motions of the stars about the north celestial pole with laser pointers but instead of continuously rotating his hand to show them moving around the pole, he just rotated back and forth, effectively running time forwards and backwards. Having taught intro astro for people who don’t know astronomy, they WILL think that’s the actual motion if that’s how you demo it.
  • Third, he said that no matter where you are on Earth, no matter what time of year, the stars will always rise 23.5° relative to straight up from the horizon. This is very wrong. For example, at either pole, stars will never rise nor set, but they will move in a circle at the same elevation in your sky.


  1. And Pamela also said that Neil Armstrong was the first man in Space….. well, he was a first at one thing, just not that one.

    Comment by Trent Voigt — July 14, 2012 @ 6:56 pm | Reply

    • I must’ve missed where she said that. I had to leave just after she showed the MoonMappers video promo.

      Comment by Stuart Robbins — July 15, 2012 @ 9:39 am | Reply

    • Hehe. I seem to recall that it was a Russian guy who became quite famous afterwards.

      Comment by GoneToPlaid — July 15, 2012 @ 9:49 am | Reply

    • Actually, I’m getting a tad ticked at AstronomyCast. They really need to do an errata episode where they go over all the mistakes Pamela has made in the show. Among them (besides pronunciation) are things like all craters are circles (~5% are elliptical until you get to 100s km across, then it’s upwards of 20%), Saturn’s rings are as thin as 1 km (they’re as thin as 15 meters), and that Carbon is the most abundant element on Earth which is why it’s what we’re based on (in fact, it’s silicon, which implies that carbon is easier for life and so we’re unlikely to find silicon-based life). She also didn’t know why the Saturnian system is sometimes referred to as the cronian system, and it’s because in Greek mythology Saturn=Cronus.

      Not that Trent’s comment had to do with AstronomyCast, but it applies overall to Pamela’s lack of correcting mistakes she’s made.

      Comment by Stuart Robbins — July 15, 2012 @ 9:56 am | Reply

  2. All GPS devices accurately determine direction or bearing based on actual movement of the GPS device. It sounds like McGaha assumed that the magnetometer found in many GPS devices is for accurately determining direction or orientation, but a magnetometer doesn’t always do so very accurately due to local deviations in the magnetic field which are created by natural sources or by man-made sources. McGaha may have been suggesting that ferrous objects such as a battery, if held very close to a GPS device with a built-in magnetometer, would affect the displayed bearing or orientation of the device. In that sense he is probably correct.

    I disagree with you regarding your interpretation of CCD image resolution. You state that “resolution, on the other hand, is how many pixels are there”. I think that you meant to say that “the native resolution for a CCD, on the other hand, is how many pixels are there versus the CCD’s overall dimensions” since a CCD’s pixel size is the equivalent of the size of the silver grains in photographic film versus the overall dimensions of the film’s exposure area. Regardless, these expressions merely express the native resolution of a CCD or of photographic film. The true resolution, as recorded onto film or a CCD, depends on the modulation transfer function of the optical system used with the film or the CCD.

    How did McGaha mess up regarding focus and depth of field? Surely he knows that the latter is subjective and that the latter also depends on the distance at which the resulting image or photographic print will be viewed?

    McGaha messed up demonstrating the motions of the stars in the night sky? If so, then I guess he has never been to a planetarium.

    I agree that McGaha is wrong when he states that the eye cannot figure out the color of monochromatic light directly and that [the eye] needs a companion source to tell [what the color is]. If his statement was true, then one would not be able to tell the color of a laser which is switched on in a pitch dark room. In fact, the color of a companion light source could readily fool the mind into applying a color shift to the perceived color of the monochromatic light source. For example, imagine using a companion light source whose spectrum is the muddy yellow of a tungsten light bulb. This companion light source will cause the mind to shift its perceived color balance, and this in turn will cause the mind to see the monochromatic light source as having a different color. Yet the mind, in the absence of all light, shifts back to a daylight color balance. Thus a monochromatic light source, when switched on and not in the presense of another light source, would be correctly perceived.

    McGaha is wrong when he states that the the perceived color of a monochromatic light source will change color with intensity, unless the intensity of the monochromatic light source becomes so strong as to completely saturate the eye’s red, green and blue cones, or unless the direction of the light source shifts away from the eye’s fovea centralis since blue cones are found mostly outside the fovea.

    Comment by GoneToPlaid — July 14, 2012 @ 11:22 pm | Reply

    • GPS magnetometer: I don’t know what McGaha was thinking. I also don’t think a battery would do much of anything unless it’s a VERY sensitive magnetometer. Unless the battery was currently being used and a charge was flowing.

      Focus / DOF: I honestly don’t remember the specifics of this one (which is why I didn’t elaborate much). It was in the context of a webcam which he said was a pinhole camera so was always in focus for everything, but I had stopped paying attention for a minute or two while he was talking about it.

      Star Motions: Yes. He had them going back and forth around his north pole star. ‘Cause he couldn’t be bothered to rotate his hand, hold the laser pointer, reset his hand, then rotate again, he just rotated it back-and-forth. He also said stars always rise and set at a 23.5° angle. I suppose he’s never been to the equator nor either pole.

      Monochromatic light comparison: Agreed that you can be fooled, but your example of a green (or red or violet or blue or whatever) laser in a dark room with no comparison is another good example that he was talking out his —.

      Resolution vs. Pixel Scale: I’ll say we’re quibbling about semantics on this one and it’s not nearly as bad as the other things and let it go. For background on the issue, though, it’s based on a crotchety reviewer correction in a paper where I wrote that the CTX camera on the Mars Reconnaissance Orbiter had a resolution up to 5 meters per pixel. That’s wrong — it has an image/pixel scale of up to 5 meters per pixel. The resolution is [some number] pixels wide (it’s a push-broom camera so it’s only “one pixel” tall).

      Comment by Stuart Robbins — July 15, 2012 @ 9:46 am | Reply

      • I agree that a steel clad battery, even if no current is flowing through it to the phone, would have to be held very close to or against the phone in order to noticeably affect the phone’s magnetometer.

        Hehe. A true pinhole camera (no actual lens) is always slightly out of focus for everything due to the pinhole’s aperture and the strong diffraction effects produced by the very tiny aperture. I don’t know of any pinhole or even single lens element web cams which are being manufactured any more. All of them now use at least a couple of tiny lens elements to give the web camera a larger aperture (for low light conditions) and to improve resolution. Yet the rules of depth of field remain exactly the same as for 35mm photography — the lens focal length and aperture versus the size of the image plane, in turn versus the distance from which the final image will be viewed.

        So wherever one is on the earth, McGaha believes that the stars will be seen to rise and set at a 23.5° angle? Was that angle relative to the horizon or relative to vertical? It really doesn’t matter since the rise/set angle for celestial objects depends not only on the observer’s latitude, but also on the declination of the celestial object. Apparently McGaha has never played around with computer planetarium software.

        Regarding your MRO paper about the CTX camera, it depends on whether or not you were talking about the limiting resolution of the MRO’s CTX optical system/CCD combination for the surface of Mars when the MRO is operating at its nominal orbital altitude. In other words, a backwards projection of a single CCD pixel through the optical system onto the surface of Mars. I suspect that you were indeed talking about the limiting ground resolution on the surface of Mars as seen by the MRO’s CTX camera when the MRO is operating at its nominal orbital altitude. The CTX camera uses a 350mm focal length Maksutov Cassegrain optical system which images onto what I assume is a Kodak KLI-5001G CCD sensor, based on the spec of 5064 total pixels for the single row of pixels. I can’t find a spec for the diameter of the Maksutov optical system, but online photos suggest that the diameter is around 3″ to 4″. In any event, the size of the CCD’s individual pixels means that the CCD is undersampling the image presented by the optical system, meaning that the Airy disk or faint stars would have a block appearance rather than a round appearance. Thus, a backwards projection of a single CCD pixel through the optical system onto the surface of Mars would indeed represent the true resolution of the CTX camera in terms of meters on the surface of Mars. I would like to read the paper which you wrote about the CTX camera since, as far as I can tell, both the limiting resolution and the pixel scale for the CTX should be one and the same since the CCD undersamples the image created by the optical system.

        Best regards,


        Comment by GoneToPlaid — July 15, 2012 @ 10:56 am

      • CTX – I wasn’t writing a paper about it, it was a mention in the Methods section that explained why I was using that data. Which made the semantic correction more annoying.

        Comment by Stuart Robbins — July 15, 2012 @ 11:00 am

  3. I hope that a blog post about the highlights of your first TAM is forthcoming. I hear some of your Colorado companions had very good showings that we would love to hear about…

    Comment by Baxter — July 15, 2012 @ 11:32 am | Reply

    • Everyone was great except those crä^Z (pronounced “Cray-tuh-thuh-Zee”) Rocky Mountain Paranormal Society guyz in those weird glowing green ties.

      I suppose I could put together a post about my overall TAM experience.

      Comment by Stuart Robbins — July 15, 2012 @ 11:57 am | Reply

  4. I second that idea. You seemed like a nice enough fellow, wouldn’t want people to think it was all errors and crankiness.

    Comment by She Fights Like A Girl — July 16, 2012 @ 12:39 pm | Reply

  5. To all those who subscribed to the comments on this post but not my blog in general, I have provided my “summary” of my TAM experience in this post.

    Comment by Stuart Robbins — July 17, 2012 @ 11:00 am | Reply

  6. “example, at either pole during the equinox, stars will never rise nor set, but they will move in a circle at the same elevation in your sky.”

    View from North Pole
    Would this only apply to equinoxes?

    My understanding being the stars are only visible from around mid Oct to end Feb, and that moving in a circle is a constant throughout the year – visible or not.

    Comment by Shane — June 2, 2015 @ 11:43 pm | Reply

    • You’re right, I was thinking the sun and applying it to the stars, for some reason. Surprising it’s taken 3 years for someone to realize my own mistake.

      Comment by Stuart Robbins — June 3, 2015 @ 9:14 am | Reply

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