Eclipsified leaf-gap shadows: nature reveals what the eye cannot observe directly


Guest post by Alec Rawls

With a weak sun well up in the clear blue sky yesterday morning I was thinking I should go punch a hole in some cardboard and project an upside down image of just how far sun was being eclipsed by the moon. Then I looked down and saw this:


Wow, about 95% eclipsed. On the Olympic Peninsula, 200 miles north of totality, this must have been about the peak. Small wind-driven movements in the leaves above are presumably why some arcs show up as thicker than others (notice the bit of blurriness in the non-instantaneous arc images). Bigger leaf gaps, being less pinholey, will also enlarge and distort the “pinhole” images. Thus the thinnest arcs would seem to provide the truest representations, coming from smaller leaf-gaps and showing less leaf movement.

Did anyone else see this leaf-gap pinhole-image effect? I wonder how many prehistoric humans saw it and what they pondered about the coincidence between these unusual shadows on the ground and the weak sun above. There are many places where trees overhang flat bare rock surfaces, especially along rivers where humans have often resided.

Confirming inversion

A short while later the leaf-gap images showed eclipse-coverage at more like 80%:


West is to the left in this picture, verifying the inverted nature of the pinhole images. Just as the earth rotates towards the east so does the moon’s orbit proceed between the earth and the sun from west to east. It turns out that the eclipse shadow passes across the surface of the earth faster than the earth rotates so the shadow proceeds along the ground in the direction of rotation, from west to east. If the ground moved faster than the shadow then the path of totality would proceed east to west along the ground but the moon would still exit totality towards the east.

I did not have eclipse glasses but for those who did, this is what you all observed, correct? That the moon departed totality towards the east? In the leaf-gap pinhole image above the shadow cast by the moon is seen exiting stage west, confirming that the eclipse-image is flipped.

And that is how I saved my retinas, August 21, 2017. Thank you momma nature. I just regret I wasn’t more systematic in recording the progress of the leaf-gap inverted-eclipse-image phenomenon. Next time somebody should get a full sequence of pictures.




65 thoughts on “Eclipsified leaf-gap shadows: nature reveals what the eye cannot observe directly

  1. Nice, I did a similar thing with the last last eclipse in Europe. I had a clump of bamboo which was nice because the hole and thus the crescents were more spaced out. Also nearer the ground so more sharply defined.
    I was very excited until I realised I did not have a film in the camera !!
    Because it all passes so quickly I did not time to reload.
    Do you have a larger version of the first image. It may be interesting to use deconvolution using the crescent to see what shadow a point source would have made.

    • By the way, the tree in this case was a large maple or similar broad-leaf tree, about 50 feet tall, at the edge of the parking lot where we were parked. The sun was more-or-less directly over the tree during the eclipse, so the shadow was right in front of us. This effect was completely unexpected.

  2. I put up a cheap plastic tarp to keep the direct sun from pouring in through my office windows every summer morning. I thought briefly about cardboard, too – then realized the tarp had weathered enough that it was full of pinholes. Didn’t even need a piece of paper; since the tarp has to be folded up at the bottom, the inner side was a perfect projection surface.
    I did take a look at the ground under the one leafy tree (actually an overenthusiastic bush) that we have in the back yard – not nearly as clear.

  3. Some folks at my workplace did The same thing by crossing their fingers at right angles with a gap between all fingers. Made a nice overlapping set of crescents on the ground during the eclipse.

  4. I saw it on a building right across the street from my house. There was a woman standing nearby using her phone to view the eclipse,not seeing the silhouette right behind her.

  5. Isn’t it amazing what conscious awareness can achieve. If only we all could accomplish so much in all our daily lives; think of all the wonders we would no longer miss. Perhaps some could even recapture the joy of life … nah .. they’d probably rather wail with their tales of gloom and doom and CAGW … their loss.

  6. I remember seeing that effect with the partial eclipse on Melbourne in the mid 80’s. I had carefully made a pinhole camera and didn’t really need it though I could project the image onto white paper. I’ve never had the good fortune to be in the right place for a total eclipse; always the wrong side of the world when it happens.
    The images through the leaves are beautiful, especially in the first photo.

  7. The best way to save your retinas if you don’t have glasses is to observe an eclipse by looking at its reflection on water. And if your feeling extra ‘nerdy’ (c’est moi) you can use a magnifying glass to check out the reflected sun/moon…

    • where does that idea come from. Reflection will polarise and thus loose some intensity but it can still blind you. Just look at the sun reflection on a normal day : it HURTS. That’s nature’s way of telling you you are doing something bad to your retina.

  8. Here in N.E. Ohio my family used two 1950’s Polaroid camera lenses in
    combination with standard sunglasses. We could rotate the lenses to
    almost any level of obscurity we wanted.
    We also did the old trick of casting little crescent shadows on the sidewalk
    running the sunlight through the bottom of a stainless steel colander.
    Mighty cheap entertainment !

  9. Very beautiful images. I noticed this half a lifetime ago with the round images. I showed with a thermometer (you need a non windy day) that the sun images are basically the same temperature as the shade itself because the only heating element is the amount of sunlight passing through the pinhole. The apparent arcs of crescent aren’t from motion of the image. Check today and you will see such clustering effects.
    I have done this for years. I posted in the eclipse threads over the past few days, advised, a Louisiana teacher on it when he posted on WUWT on what to do for his students. I’ve asked Anthony on his recent thread how to post cell phone pictures on the blog and didn’t get much response, although I’m now travelling and haven’t checked thoroughly to see. I also have the photos of the round images from an earlier photo shoot of the phenomenon
    I’ve shown students how to calculate the diameter of the sun using the round images under the tree and proportional triangles.
    From your image sizes I would say you were under a fairly tall tree, more than ten meters to the pinhole for a decent – sized image of 10cm (4″).

    • Going back outside to look, the canopy above extends from about 25-40 feet up. Good rough estimate on your part.

  10. My son in LA used this technique and a lady asked if he was a sidewalk inspector since it was about time that something was done to the sidewalk. He told he he was watching the eclipse, and she said “well you are looking the wrong way” and walked off.

  11. Alec: A great observation and a lovely photograph.
    Everyone: Next time you look at the dappled orbs of sunlight dancing on a forest floor, know that these too are the focused images of the sun.

    • Right. I was thinking that. It is only revealed when there is something distinguishing about the face of the sun.

  12. These natural pin hole cameras were what I was anticipating, but confounded by the diffuse light through the overcast. Was the overcast caused by the cooling of the eclipse? I think so.

    • I think not. We were in the path of totality, and throughout the early afternoon clouds were building to the south. After the totality, and the cooling, I noticed that the clouds were visibly smaller. However, they quickly rebuilt afterward.

  13. I was on my Atlanta-area front stoop using a Ritz cracker box pinhole projector to observe a clear but tiny image when I refocused slightly and saw this same effect a few feet away. Once again, my ingenuity easily bested by nature!

  14. I used a monocular, gaff-taped to a camera tripod, projecting on a piece of printer paper. Shaded the paper with a shipping envelope with a hole cut in it, placed around the monocular. Completely kludged, but it worked pretty nicely once I held the paper up to the right spot to focus.

  15. At Santa Fe College in Gainesville FL we set up a large Celestron telescope in the forecourt of the Planetarium, and projected the image of the sun and moon onto a white screen. Huge crowd of interested visitors as the sun, sun spots, the moon moving over the sun (to 87% of totality here), and even the jagged edge of the moon’s image caused by the mountains of the moon. Then we turned and looked behind us at the shade of the trees on the sidewalk, and there were all those perfect crescents. The public was enthralled.
    The remaining sunlight was washing out the image, so I ran to my car and got an umbrella, and my job became holding the umbrella over the screen. I explained to the crowd about all those years in graduate school learning how to do that.

  16. I witnessed totality in Russellville, KY, and I enjoyed pointing out the crescent shadows to passers-by while we were eagerly anticipating the big moment. Got a few good photos too.

  17. Out in the Shirley Basin there were no nearby trees to make these shadows, so I showed my kids that crossing one’s hands with slightly opened fingers does the same.

  18. I saw this pattern on my brick walk, under the shade of a large sycamore tree in Orange county NC. It was not evident on the adjacent grass. Then I went inside and saw the same pattern projected through West-facing windows inder the,shade of the same tree. It was very cool and unexpected, and I wondered how many others were reaping the rewards of looking in other than the consensus direction.

  19. You can create the same effect with your fingers. I showed a bunch of folks how to do it and they all loved it.
    You simply extend our two longest fingers on both hands and cross them to make a little tic-tac-toe board with their shadow. The little squares of light on the ground display the same effect.

  20. We saw that in spades at our ocean front park while using our pinhole viewer. We actually saw two types. The seagrape trees produced random pinhole images like those in the post. But the coconut palms produced double rows of aligned images where the closely spaced frond leaves met frond stems. Quite magical. And when the temperature drop kille the sea breeze, very crisp because still.

  21. The eclipse gave us a much-needed break and distraction from the crazy hatefulness which has gripped our nation. Cool picture! Enjoy being back in the 17th century!

  22. The same effect can be done with a collender/pasta strainer. Showed the kids this on Monday off and on during the eclipse. It was nearly as cool as the special glasses.

  23. While everyone else was looking up through safety glasses, I always look down during partial eclipses. I love to walk under the trees to see the crescent shadows, to make pin holes with just my hands, and look at how funky the edges of some shadows become.

  24. In Colorado with 90% occlusion, There was a point during the sun’s re-emergence when its light resolved details of leaves against our paito pavement with incredible detail, to the point of showing serrations on our maple tree. The interesting thing, in hindsight, is that I’m not positive about whether the latter detail was just a product of my imagination, as the cool wind was causing the branches to wave about a little, but I could definitely distinguish maple and locust trees by their shadows for a certain period. Prior to that, what had been so noticeable had been the crescents.
    Looking down during an eclipse has its merits.
    After reading your post discussing the evolving quality of shadows you saw, it occurs that light that penetrates more distinctly through the gaps is laser-like, more focused and intense than when the sun’s light comes from its full face, which must cause a lot of diffusion. I’ve never seen anything like it.
    I planned on looking up too, but MacDonalds didn’t have a pair of those glasses when I went in. Er, Monday. About an hour before. Had to buy a quarter pounder and fries as solace.

  25. Thank you Alec for the multiple image post under the partial shade tree that I had notified people to look out for who couldn’t travel to the line of full eclipse. Your point about the relative motion of the moon’s shadow coming at us from the west (as the moon overtook the sun at about 12 times its own slower single degree per day along its “ecliptic” course among the stars that actually just reflects our own earth orbital viewing point) gave a back of the envelop average calculated speed from west coast to east coast of about 1600 miles per hour during its hour and a half traverse. This equivalent of a Mach 2 jet fighter or the velocity of a rifle bullet arrival of the dark lunar shadow upon those experiencing the full eclipse was as you say the product of an actual Mach 3 speed across the surface of the globe diminished by our own planetary rotation of eastward of around 700 miles/hr. for U.S. latitudes.

  26. In the 1960s, my brother discovered that the best place to was the partial eclipse was in a silver maple tree. Besides being a good climbing tree, the deeply lobed leaves made very good pinhole cameras and we could adjust the density of images by climbing higher or lower.
    I mentioned it in my solar projection page

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