Picturing the Eclipsed Sun with a Holy Leaf

Pinhole images occur in nature, as you can discover lounging in the shade of a tree whose leaves have been perforated by insects. Likely, someone remembered those little round spots of light that had inexplicably turned into crescents before the world darkened. Odd-shaped spots, all facing the same way, are certainly striking, evoking a sense of warped reality. Even if you can’t articulate what’s different, you feel as if “something is happening.”

     If you are watching for a solar eclipse, just hold a perforated leaf at arm’s length toward the sun, the way that a child instinctively does to backlight an autumn leaf. Look down at your chest to the leaf’s shadow — and see the little crescent of light in the midst of the shadow. The leaf is probably the world’s first portable pinhole device. As you move the leaf farther away, the light spot changes from the shape of the insect’s hole to the shape of the eclipsing sun. The smaller the hole, the sharper the image.

     Once you get the idea that the hole’s the thing, you may no longer require the assistance of a leaf-cutting insect or a plant species with naturally perforated leaves, such as the philodendron species commonly called Swiss Cheese. Just punch a hole with a twig. Or, if leafless, merely cross your fingers (for good luck?) to produce a small opening and inspect your hand’s shadow for a little crescent.

I almost didn’t see the midday eclipse in Seattle that got me started on nonstandard pinhole methods; the path of totality was over Canada, and the calculations showed that it would be less than half-total in Seattle [in 2017, it will be 92% covered]. Furthermore, at the hour of the eclipse, it was overcast in Seattle, though the sun seemed on the verge of reappearing from behind a high, thin layer of moisture. I peeked through the window shades of a south-facing window, and thought the prospects of seeing anything quite poor. The clouds were so bright that I couldn’t even distinguish the sun, much less its shape. Yet the sun was casting modest shadows of the window frame across the desktop.

Then I noticed the spots of light on the ceiling. Obviously, they were reflections of the sunlight, off of something on the desktop. The spots moved — ah, my wristwatch was reflecting the sunlight. I tried covering the crystal face of the watch with two fingers, and the large, round spot on the ceiling disappeared.

Yet the small ones remained. And they seemed crescent-shaped. Nothing was crescent-shaped on my watch. I tried covering each little shiny patch of chrome at the bracket where the wrist strap attaches. And the crescent on the ceiling suddenly disappeared.

The chrome patch was a small rectangle, not crescent. And then it finally dawned on me: the crescent on the ceiling is the shape of the sun when partially eclipsed. Even though I couldn’t see the sun looking out the window because the nearby clouds seemed so bright, the image was amazingly sharp. The chrome rectangle was simply acting like a pinhole camera, combined with a mirror.

Once I had the idea (one that has probably been invented by many a school teacher over the years, trying to keep the children from looking directly at the sun), I took off the watch and propped it up on the desk, repositioning it so as to lower the crescent from the ceiling to the far wall of the room, where it was darker. Now I could walk up to the wall, take off my glasses, and closely examine the crescent. The nick that the moon had taken out of the sun was quite visible. Over the course of the next hour, it changed; the sun was never more than half-covered before the nick began to retreat.

I had some time to play around with the size of the mirror. When I used a small rectangular mirror, borrowed from my wife’s purse, I only saw a rectangle on the wall. Similarly, when I used a small dental mirror, I saw only a round spot and not the crescent shape of the partially eclipsed sun. I used some bandage tape to mask most of the little mirror, leaving only a small hole unobscured. And finally the crescent shape appeared on the wall. The size of that facet on my watch seemed just about right, close enough to a pinhole for the shape to be that of the light source, rather than the reflector.

Crystals, at least those with many small-but-flat reflecting surfaces, also ought to be useful for viewing eclipses; a small facet serves to combine the pinhole with a mirror. Pull the shades except for a small opening, lay your crystal or jewel on the window sill in the sunlight, and walk up to inspect the crescent spots reflected onto the walls. A square millimeter seems about the area needed for a mirror to function as a pinhole; little spangles embedded in a plaster wall would work nicely. A cave with a ray of sunlight coming in the smokehole, touching a shiny piece of mica, could have been the first movie theater, entertainment for the dozens — if you don’t mind giving away your secret of eclipse forecasting.

Either leaf or crystal or crossed fingers would allow an alarm for a total solar eclipse, were this technique routinely used during the day of the new moon. The knowledgeable would likely warn the others to start praying. It’s another entry-level eclipse forecasting method, simple enough not to require planning or antecedent techniques. It gives an hour’s warning of possible totality rather than the many-months-ahead prediction of the counting-by-sixes clenched fist method.

So eclipse Method #2 might be called the “Holy Leaf” or “Crossed Fingers.” And the crystal (or jewel or piece of broken mica) is its slightly-harder-to-discover corollary. Since prehistoric peoples probably wouldn’t have understood the principle by which the holy leaf and the crystal were related, I suppose that I’d better just call it Method #3 (“The Crystal”), rather than merely a corollary, since they were likely to be discovered independently of one another.

Since that day with the wristwatch, each time that I’ve been in a cathedral observing rays of sunshine illuminating a jeweled altarpiece, I’ve wondered if the architecture and the jewel facets were influenced by an ancient practice of just that sort.