Reflections of an Eclipse

05288-500Snappy title, huh? Actually, it should be, “Using a Mirror to View the Total Solar Eclipse,” but I thought that a bit dry.

(Image of the McMath Pierce Heliostat mirror at the Kitt Peak National Observatory. Credit: NSO/AURA/NSF )

If you can get past all the hype and hysteria, the August 21, 2017 total solar eclipse will be an event to remember, and it will be all the more special if you view it yourself.  Seems like some people are just out to make a buck, though, selling memorabilia and fake observing glasses. But even if you were lucky enough to get your genuine and safe viewing “glasses,” the image you will see will be very small. If you want to share with a group, you’ll want something bigger.

Here’s the latest solar image from NASA’s Solar and Heliospheric Observatory (SOHO). The mirror projection method described here will not provide such a large and detailed image as this (neither will it be yellow-orange!), but it will display the partial phases of the eclipse quite nicely. And at other times, you will be able to see large sunspots.

By the way, this is the basic method used at large solar observatories. The image at the top shows the mirror at the McMath Pierce Heliostat at Kitt Peak National Observatory in Arizona. It allows highly detailed images of the Sun. Our instructions call for a somewhat more modest mirror.

Pinhole projection, which you will find suggested in many places, is a common method. This is good, and it works, but the small size of the image is still a bit disappointing. Instead, you can make a nice image 3 or 4 inches across or even larger using a variation with a mirror. It’s the same basic physics, except that you reflect the light onto a wall instead of a small piece of cardboard. [Interestingly, the two methods show the same difference as that between the two major types of telescopes, refracting (which depends on a lens) and reflecting (which naturally depends on a mirror.)]

Here is a basic graphic showing how this works, and instructions based an excerpt from an activity I give to my students that involves projecting an image of the Sun:


You will need a very small, flat (non-magnifying) mirror. You need something roughly a quarter inch across. Since such small mirrors are rare, you can use a larger mirror, but you must block out all but a small hole. Make a small round hole (about 6 or 7 mm, roughly one quarter of an inch, is good) in black construction paper and mount this on the front of the mirror so that the mirror only shows through the hole. In a pinch you could use a large index card for this, but black construction paper is preferable.

Patti Sand Sun Mirror on TripodThe image on the left is from a former student, Patti Sand, for her class project in which she measured the diameter of the Sun, not observe an eclipse. She attached a flat compact mirror on a tripod, with paper blocking out all but a small hole exposing the mirror.

PattiSand3The image on the right shows how Patti reflected the image through an open door onto the wall  in a darkened room.

PattiSand4This last image shows what the Sun looked like on the way. Please note that it looks oblong because of the angle of the camera. There are also markings on the wall that were part of Patti’s project.

You could also use a dental mirror, which is what I used for this example, but you will need to project the image maybe 35-50 feet to get a good, well defined image. The larger the mirror, dentalmirrorthe father you have to reflect the image to get good resolution. The key is experimentation before hand.

Determine how you will mount the mirror in order to be able to aim the reflection of the Sun onto the wall. It is preferable that the mirror be located at approximately the same height above the ground as the reflection will be on the wall. Using a tripod as illustrated is an excellent way to do this, although there are many other way you could do it. The exact method is left to you. Holding by hand is of course one way, but you have to have a steady hand.

Find a suitable location to perform the observation. The easiest way to do this is to project onto a North-facing wall around noon. The wall onto which you project needs to be in shadow so that you can see the image well. Furthermore, it needs to be round in shape rather than oblong. If you follow the instructions carefully, you will get a round spot on the wall that is, in fact, an actual image of the Sun. It may not be terribly sharp and detailed, but it is an image as opposed to simply a reflection of the shape of the mirror or cut out.

Experiment with sizes and distances to find something that works for you. But keep in mind that the ratio of the size of the reflection distance (“l” in the graphic) to the size of the mirror cutout should be in the order of 1200 or 2500 to one. A 6 meter reflection from a 7 mm mirror fits the lower end of this ratio. That is about 23 feet distance for a quarter inch hole. These are just suggestions. The exact measurements are not terribly critical here, but you need to be close to this ratio and you do need to be projecting onto a light surface in a darkened room.

Experiment with sizes and distances to find something that works for you. But keep in mind that the ratio of the size of the reflection distance (“l” in the graphic) to the size of the mirror cutout should be in the order of 1200 or 2500 to one. That’s a fairly large range. When using a 6-7 mm (quarter inch) mirror or cutout, it’s best that you do not use reflection distances (“l”) of less than 7 meters (about 23 feet) or more than 15 meters (nearly 49 feet). The reason for this is simply that if the projection distance is too short, the image will be bright but too fuzzy (out of focus); if the distance it too great, the image will be sharply defined, but dim and difficult to see. With a 6-7 mm hole,  a distance of 7-15 meters is about the best range when projected onto a flat surface in the shade.

In general, use the shortest distance that provides you with an acceptable image. These are just suggestions. The exact measurements are not terribly critical here, but you need to be close to this ratio and you do need to be projecting onto a light surface in a darkened room.

 Again, the larger the mirror, the father you have to reflect the image to get good resolution.

Of course, standard precautions hold. Do not look directly into the reflection and be careful not to reflect it onto people or animals. This does not intensify the heat like a magnifying glass, but it is still bright sunlight and should not be observed directly.


mirrorprojectorFor the record, here is my quickly thrown together set up on Friday, August 17 using a tripod, a dental mirror and an index card cut out mask with a hole-punch hole (about a quarter inch). I reflected the sun from the tripod to the back of my garage onto a piece of white foam core. The distance was roughly 35 feet or approximately 10.5 meters.

sunAs you can see, there is a distinct circular image. Unfortunately, the sunspots currently on the Sun’s surface are not big enough to resolve with this method. This is, of course a fairly crude set up. Still I have seen large sunspots before using a set up like this. During the eclipse, the crescent shape of the partially eclipsed Sun will be quite distinct.

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Getting Past the Eclipse Hype

79eclipseConsidering the absurd level of hype and some of the more ridiculous exaggerations and crackpot  claims of mystical silliness, I am sorry to say that I will be glad when the whole thing is over.

Eclipses are amazing and beautiful. I witnessed the 1979 total eclipse in Williston, North Dakota, as well as partial eclipses before and since. . Such an event is worth your time and effort, and I am hopeful that this one will inspire an increased interest in science. That’s the good part.

But I am concerned that the reported traffic congestion, lack of accommodations and the hordes of hopeful eclipse watching pouring into small towns across the country will result in a less than happy experience. And instead of blaming the over-exuberant media that hyped it, disappointed observers will blame astronomers and science in general.

And then some will miss it altogether by the actions of  ill-informed and over-protective parents and school administrators. I know of schools here in Colorado where students will be prevented from even going outside during the eclipse, with or without the special glasses. I even heard the mother protesting these restrictions claiming that she wanted her child to see this amazing event because it would grow as dark as night, she claimed, even in our roughly 90% totality. As one who has seen a similar eclipse, I assure you that it does not grow “dark as night” even in the path of totality. (It will be like a fairly deep twilight, with brighter skies around the horizon.) Here in northern Colorado it will perhaps grow as dim as an overcast day, but hardly dark.  There is just so much misinformation and so much being taken out of context.

Let us hope that I am wrong and everyone has a good, educational experience..

But the really annoying aspect is coming from the wingnuts predicting the end of the world (again), the dangers of lizard men, massive power failures or even the appearance of the fictional planet Nibiru that supposedly will crash into Earth 33 days after the eclipse. Then there are less dire but no less absurd claims of a new level of cosmic consciousness or other such mystical woo woo.

Now, I am hopeful and even confidant that the majority of Americans won’t buy into this weak-brained nonsense, but given our current political situation it is very clear that many are swayed by sensational claims, vacuous promises and irrational ruminations.

So please folks, enjoy the eclipse, and help others realize that it is a perfectly natural and predictable event, useful for inspiration as well as scientific interpretation. It is not a religious sign, a mystical portent or anything to be feared. Let’s hope that people can all grow up a little.

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The Last Total Solar Eclipse in the USA

1979 Total Solar Eclipse by Larry C. SessionsI have seen references several times lately online, including an article in Popular Science, stating that the last total solar eclipse visible from the United States was in 1918. This is simply not true. There have been several total eclipses visible from portions of the US since then, including the last one on February 26, 1979. I can attest that this one was visible, as I personally witnessed it in Williston, North Dakota, with the crew from the Fort Worth Museum of Science and History.

Astronomers from the United States Naval Observatory planned to make observations during the 1918 eclipse to test Einstein’s recently minted General Theory of Relativity. Unfortunately, the observations in Oregon were clouded out, and the honor of successfully testing Einstein’s theory fell to British astronomer Arthur Eddington, based on observations of an eclipse in 1919, which did not cross North America. 

TSENorAm1901This map illustrates solar eclipse paths across the US in the early 20th Century.

Despite widespread pubic interest, no such major scientific import falls to the 2017 event. The next solar eclipse visible in the US is in April, 2024, which runs from Texas northeast to Maine. An even better opportunity comes on August 12, 2045, when a wide path of shadow (umbra) runs from Northern California to Florida. This path will pass right over my home town, but chances are, I will miss it.

TSENorAm1951This map charts solar eclipse paths including the February 26, 1979 event.

For the record, it is estimated that any specific location on Earth, a total solar eclipse can be observed on the average about once every 300 years. However, specific locations may not be so lucky.

20264870_1384030974965841_20876766761428793_nHere in Denver, the last total eclipse was the famed one mentioned above, on June 8, 1918. Although several not-quite-total annular eclipses will occur before then, the next full on total eclipse viewable from Denver will be on July 22, 2772. I think I will miss that one as well.


Thanks to Fred Espenak and NASA for the maps and predictions, the Central Arkansas Astronomical Society (CAAS) and The Denver Post for the clipping.

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Einstein and Eddington

EinsteinandeddingtondvdcoverWe had a free week of HBO so we decided to check out a couple of movies. The first was Einstein and Eddington, a BBC/HBO docu-drama about the relationship between Big Al (more appropriately, “Al Who?” at the time) and Cambridge astronomer Arthur Eddington (later Sir Arthur). (Trailer: In particular it was about Eddington’s “proof” of General Relativity, which made “Einstein” a household word around the world.

It was an interesting show, and worth the watch, with David Tennant (Eddington) and Andy Serkis (Einstein). Throughout the movie, I could not help but imagine Serkis portraying Robert Downey Jr. portraying Einstein. Serkis, you may know, was the voice of Gollum in the Lord of the Rings trilogy.

I was not up on all the historical details to be sure how accurate most of the movie was, but one thing I must note is that the depiction of the 1919 eclipse was for dramatic effect and scientifically abominable. It was noted, accurately, that the eclipse would occur when the Sun was near the star cluster The Hyades, but in the depiction, the event was set in the constellation Scorpius, which is in the opposite part of the sky.

In this screen capture from the film, enhanced a bit for clarity, the grossly  oversized eclipse is shown occurring in the constellation Scorpius with the “Teapot” of Sagittarius to the left. In reality, the 1919 eclipse occurred in a completely different part of the sky, the constellation Taurus.Capture

In addition, the eclipse appeared much too large, and progressed with ridiculous rapidity. In fact, in what was referenced as five minutes before totality, the partial phase hadn’t even started. When it did, the stars were immediately visible, even though in reality the sky is much too bright until the actual period of totality. Clearly the whole sequence, which is actually only a minor segment of the 94 minute file, was directed by someone who had never seen an eclipse. Too bad.

It is good to get scientific concepts out the to public. In fact it is desperately needed. Who cares if there are a few little inaccuracies if the overall picture conveys the positive message of scientific advance? Artistic license is as old as humanity and a legitimate practice in many instances.

But in the depiction of science I think we need to be careful, especially in visual presentations. A real solar eclipse bears little resemblance to what is shown in this film. A real eclipse is a much more drawn out affair, and frankly somewhat boring during the 90 minutes or so of partial eclipse before totality (and then again after). Virtually everything of interest takes place in the few minutes of totality. This was, in fact, intimated in the film, although the circumstances were incorrect.

Although I was not well versed in the historical aspects of the movie, I did question one or two things that did, in fact, turn out to be erroneous. It turns out that there were a number of these historical errors are listed here:

Overall, Einstein and Eddington is worth seeing, but keep in mind that in some ways it is more art than accurate.


P.S. the other film was The Revenant, a dark and depressing film for which I can find no redeeming value. The acting was pretty good, I suppose, but there were glaring inaccuracies  such as filming in the Canadian Rockies (and Argentina) and passing it off as the Great Plains (Nebraska and the Dakotas, home range of the Pawnee and Arikara “Rees”). Even if the action wandered afield a bit, the mountains did not fit any more than in the original “True Grit” film, where Colorado substituted for eastern Oklahoma and western Arkansas). One particularly egregious scene appeared to have been shot in a wet Pacific Northwest Coastal rain forest. It is not a film for the squeamish and certainly not if you are looking for something bright and sunny.

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Earth’s Forests are “Diminished Imitations” of “Real” Trees

eyehour_hstI want to be optimistic about humanity — I really do. But it seems like every morning I wake up to a new low in the annals of human stupidity.

Let me make up an example. This may be believed by some people for all I know, but I am just using it here to make a point.

I know of a gas cloud out in space, called MyCn 18, that looks remarkably like a human eye. Therefore, since it looks like an eye, it must be an eye. And since it is this great and magnificent eye in space, it must be the eye of God himself (herself). Do you follow my reasoning here? I’m sure you will agree that this makes sense, right?

Disregard the facts that the rest of God’s body is invisible and presumably He (She?) is a cyclops, or the clear evidence that this is really the end result of a star at the end of its lifetime. No, let’s just ignore the information that reason and astronomical evidence provide, and proclaim that this is the veritable eye of God, just because it looks like what I think it the eye of God should look like. Reasonable, wouldn’t you agree?

lead_960Well, that is essentially the process that has gone on in the mind (I use the word loosely) of a Crimean video producer (Людин Рɣси ) who apparently thinks that the Earth is flat and all our forests are fakes, or at best miniature versions of “real” trees. The evidence? Geological structures around the world that bear a resemblance to giant tree stumps, such as Devil’s Tower in Wyoming.

Since Devil’s Tower looks like a giant tree stump, it must be a giant tree stump, and as such it serves as clear evidence of the real forests that once covered Earth.  Impeccable logic, as anyone can see.

Yeah, right. While there are perfectly good geological explanations for such structures, supported by solid evidence and reasonable physical processes, some people would prefer to believe their own fantasies, perhaps because their minds are too small to accept reality.

It is just stupefying that even one person would be deranged enough to buy this, but the thought that the video has been viewed hundreds of thousands of times and that “thousands” of people are ready to believe this bilge is simply brain numbing. The “concept,” if we are willing to call it such, would be on a par the idea that squirrels are little aliens in disguise who are plotting to take over the world and erect a temple in which to worship the Great Pumpkin. I mean, honestly, this is pure insanity.

Certainly the Internet bears major blame here. We have always had idiots, but the Internet just makes it easier for them to display their stupidity.

Maybe I shouldn’t even mention this or pass it on, because it may thereby reach susceptible warped minds that will believe it. But I trust that anyone reading this is not at risk, and it just fascinates me to know that such morons exist. To be clear, I am referring  to the people who believe this crap, and in particular the flat-earther who made the video, not to Sam Kriss, the author of the article in the Atlantic.

Well here, read it yourself:

To be honest, I have yet to figure out what this has to do with the “concept” of a flat Earth, but it certainly is on par with that kind of warped thinking.

* * *

(By the way, there are a number of gas clouds in space that look at least vaguely like eyes. Most are the product of stellar death, known as “planetary nebulae” because they also look a bit like planets through a telescope. One in particular, usually called the “Helix Nebula,” is also called the “Eye of God” or sometimes, “The Eye of Sauron.”)

(Photo of Devil’s Tower courtesy of the National Park Service.
The Eye of an Hourglass Nebula Credit: R. Sahai and J. Trauger (JPL), WFPC2 Science Team, NASA)

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Lies, extortions and threats

DistressLies, extortions and threats. How long must America endure such blatant and un-American activities from the White House and Congress? What can we do? I’m not sure what it will take.

Some folks think I should just chill. See what happens. Maybe the threat will go away. Maybe there is no threat. It may just be “all blow and no show” they say. Or maybe sticking our heads in the sand will work.

Personally, I say that if you don’t at least express your concern — if only through letters emails, whatever — then you are empowering those who want to tear down our Democracy and replace it completely with an oligarchy of the rich and powerful.

Is this what America has come to?

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"… a ginger cat having a fit in a bowl of tomatoes."

Is this how Mark Twain described a painting of English Artist William Turner?

Slave ship by Willima TurnerBecause I am interested in the Sun, I have been reading  Chasing the Sun, The Epic Story of the Star That Gives Us Life by Richard Cohen. Chapter 24 (“Drawing on the Sun”) relates to the Sun in art, something that normally would not be of great interest to me. I like art, don’t get me wrong, but much of what passes for art certainly does not fit my taste.  I remember once describing a piece of modern art as making me think that someone had thrown dirty dishwater onto a white towel and then framed it.

On the other hand, I do like certain pieces of Impressionism, and I came across a quote that intrigued me in on page 431 of Cohen’s book. It was a description of an unnamed painting by William Turner, who was obsessed with light, especially sunlight,  and color in landscapes. This painting, Cohen writes, was described by Mark Twain as “like a ginger cat having a fit in a bowl of tomatoes.”

As a fan of Twain, it did not take much to conjure up an image in my mind, and the quote gave me the giggles every time I read it. Certainly it sounds like Twain, but Cohen gave no reference for the quotation in his otherwise well documented work. He did not even identify the specific painting, which I now desperately wanted to view myself.

I thought that if I could find the context of the quotation I could determine which of Turner’s paintings it was. At  first I searched Google and came up only repetitions of the supposed quotation, with useless and vague references that were no good at all. Interestingly, many of the instances I found were unattributed repetitions of specifically phrased quotations apparently from other web sites. In other words, they were plagiarized quotations of the quotation.

Next I tried my own small collection of Twain’s work, in paper form, and found nothing. Finally, I decided to search as well as I could among the Twain offerings on the Gutenberg Project ( I never found the exact quotation, but I came pretty darn close in “A Tramp Abroad.”

It referenced a Turner painting, “Slave Ship” and this phrase: “A Boston newspaper reporter went and took a look at the Slave Ship floundering about in that fierce conflagration of reds and yellows, and said it reminded him of a tortoise-shell cat having a fit in a platter of tomatoes.”

That was it. The quotation got mangled a bit, but the image in my mind was the same. So it was not Twain’s quotation per se, but rather his repetition of the words of an anonymous reporter. Still, was there really a “Boston reporter,” or was this fiction, as is much of Twain’s book? I guess we will never know, but at least now I know the painting and the correct quotation.

The painting is not quite as wild and psychedelic as I had imagined, but the description fits it well. Incidentally, just last evening I saw similar coloration in the sunset sky from Denver, although certainly not as busy and intense as in Turner’s painting. In the painting, the actual objects take second place to the mood and lighting. Even the Sun, our mighty day star, was reduced to a bright smudge. It took me a while before I even saw the ship itself, and longer to notice some, shall we say more “sinister” aspects. Take a look for yourself.






From Mark Twain’s “A Tramp Abroad”:

And then there is painting. What a red rag is to a bull, Turner’s “Slave Ship” was to me, before I studied art. Mr. Ruskin is educated in art up to a point where that picture throws him into as mad an ecstasy of pleasure as it used to throw me into one of rage, last year, when I was ignorant. His cultivation enables him—and me, now—to see water in that glaring yellow mud, and natural effects in those lurid explosions of mixed smoke and flame, and crimson sunset glories; it reconciles him—and me, now—to the floating of iron cable-chains and other unfloatable things; it reconciles us to fishes swimming around on top of the mud—I mean the water. The most of the picture is a manifest impossibility—that is to say, a lie; and only rigid cultivation can enable a man to find truth in a lie. But it enabled Mr. Ruskin to do it, and it has enabled me to do it, and I am thankful for it. A Boston newspaper reporter went and took a look at the Slave Ship floundering about in that fierce conflagration of reds and yellows, and said it reminded him of a tortoise-shell cat having a fit in a platter of tomatoes. In my then uneducated state, that went home to my non-cultivation, and I thought here is a man with an unobstructed eye. Mr. Ruskin would have said: This person is an ass. That is what I would say, now.

Months after this was written, I happened into the National Gallery in London, and soon became so fascinated with the Turner pictures that I could hardly get away from the place. I went there often, afterward, meaning to see the rest of the gallery, but the Turner spell was too strong; it could not be shaken off. However, the Turners which attracted me most did not remind me of the Slave Ship.

A Tramp Abroad on
Quote above near the end of Chapter XXIV (24), just search for “tortoise-shell”

The Slave Ship painting by Turner:
J.M.W. Turner, The Slave Ship (1840). Oil on canvas. 90.8 × 122.6 cm, Museum of Fine Arts, Boston.
chasingthesunChasing the Sun by Richard Cohen

Posted in Art, Color, natural history, optical illusion, Painting, Sun, Uncategorized | Tagged , , , | 1 Comment