Sunlight Artifacts and How to Observe and Photograph Them

John F. Green

WARNING: The phenomena described should be observed through dark sunglasses when the observer is located as described by the author. Readers are warned to never attempt the observations described here using binoculars or a telescope and to never observe the direct sun.

Many years ago in southeastern Wisconsin on a crisp, clear autumn day, I was for some reason no longer remembered scanning the sky near the Sun with my binoculars. Suddenly a brilliant white speck crossed the field of my binoculars followed by several more. The longer I looked, the more of these objects I saw. It didn't take long to figure out that what I was seeing were seeds of some sort, like thistle seeds which float on the wind. Their appearance was so spectacular that I resolved to investigate the matter further. I contrived to place myself in the shadow of my two-story house and continue observations. This had two advantages, for it kept me from accidentally looking at the sun, and it shaded my objective lenses, which improved the contrast of the scene.

I have since learned that I can see the same phenomenon with the naked eye through dark sunglasses, which is far safer when done properly. The view can be absolutely captivating with various bright specs against the blue sky moving at different speeds and angles. With low sun angles in the late afternoon the light sparkling and shimmering off the wings of dragonflies and such can be quite enchanting.


History

I am certainly not the first person to see or even report these objects. Indeed a search of the astronomical literature of the last two centuries will turn up a number of references to this phenomenon. In several cases, skilled observers have referred to "daytime meteors" and, surprisingly, seem to have been clueless about what they were actually seeing. Others immediately recognized them for what they were. Included here are three of these accounts.

John Coles, Observatory, 24:387, 1901. Yesterday, 18th September, having let my sidereal watch rundown, I set it to sidereal time in the usual manner, to test this accuracy, I went to my Observatory and brought Arcturus into the center of the field. This was at two hours 15 minutes p.m., in bright sunshine. While I was looking at the star, a shower of meteors, which nearly occupied the whole field of vision, passed from west to east, some nearly as bright as Arcturus. I then sent my driving clock in motion, and thinking that possibly there might be something wrong with my eyesight, I called my wife, and on looking through the telescope she at once saw the meteors, but the principal shower had been passed. However they continued to pass across the field at the rate of about 12 a minute, sometimes more, while the star remained in the center of the field, all coming from east to west. I continued watch until about 3 PM, when the meteors had nearly ceased to appear.

I had never heard of a shower of meteors being observed in bright sunlight, but I am perfectly convinced that I am not mistaken, especially as my wife, who has very good eyesight, saw them quite plainly. My telescope, a seven inch Newtonian, is in perfect adjustment, a Kelner eyepiece was used, and my GMT is correct to within a second. As I have mentioned, Arcturus remained in the center of the field after the driving clock was in motion.

William Nobel, Observatory, 24:418, 1901. Like Mr. Coles, I have observed daylight meteors (?), and possibly my experience may enable him to account for the phenomenon witnessed by Mrs. Coles and himself on September 18th.

Some years ago, while scrutinizing the Sun's limb --- which at that particular instant I had suffered to travel just out of the field --- I was startled to see a shower of luminous objects driving rapidly and nearly horizontally, which must, from the direction of their drift, have apparently crossed the Sun's disc immediately afterwards. They were notably bright; but as I was struck with the imperfection of the definition of them, and with the fuzziness of their tiny disks, it occurred to me to try to focus accurately upon them. On doing so, I found at once that the eyepiece had to be racked out, and on obtaining the true focus for my meteors (?) Discovered that I was looking at hundreds of pieces of Thistledown driving on the wind, and brilliantly illuminated by the sunlight. Having once seen them clearly and sharply defined and satisfied myself as to their nature, I discontinued my watch so I am unable to say how long the shower lasted. Inasmuch as the thistle seeds were probably less than 30 or 40 yards from the object glass of my equatorial, and the sun was more than 93 million miles off, the necessity for a considerable change of focus will be at once apparent.

Should Mr. Coles witness a recurrence his daylight shower, perhaps I may venture to suggest he should repeat my experiment of focusing, not on Arcturus but on the objects themselves.

Eugene Spiess, Strolling Astronomer, 13: 118, 1959. About two years ago while pointing the scope toward the clear blue sky in order to measure the exit pupil with a micrometer. I was amazed to see what appeared to be white round luminous objects travel across the field of view at great speed. Thinking they were reflections or eye defects I moved the scope but this showed that they were real objects picked up by the objective lens. They would only be in the field of view from a fraction of a second to one second, and I was unable to focus on them. These objects intrigued me, and I started keeping a record of the number and time. The record showed no pattern of any kind.

In order to try and resolve them, I mounted three refractors with the optical axes parallel to each other. One telescope I focused on the sun (with suitable filters), the second I focused on point closer, and the third was given a still closer focal setting. By moving from one eyepiece to another quickly, I could determine which scope was the closer to being in focus. By experimentally focusing, I was able to resolve the objects. They turned out to be out of focus objects carried by the air streams and different altitudes. This evidently was the reason for the difficulty in trying to focus one scope on the objects seen for such a short time.

Anyone wishing to observe these objects should point to scope to the ecliptic from 10 to 20 degrees east of the sun against the clear sky. They can be seen either east or west of the sun; but with the scope east of the sun there is no chance of the Suns creeping into the field of view, with possible eye damage. You may not see any objects the first time you observe. They seem to appear sporadically in singles or in groups. Between two and three o'clock in the afternoon in a cloudless sky I have observed up to 35 in one hour. They are all shapes and sizes. One which I got in focus appeared to be an unrolled roll of toilet paper. I could observe it to be changing shape as it traveled across the field.

Perhaps if someone could calibrate his scope for known distances and different focal settings and measure the field of view he could calculate the speed of the jet streams in the upper atmosphere. These objects are interesting to observe so take a look sometime.


Types of Objects

While probably the most common and most easily seen objects are seeds of various kinds, which appear as bright round spots, I have seen a number of other bits of flotsam upon the winds. Sometimes insects can be seen. They can be recognized because they tend to flicker or shimmer and often move against the wind. Feathers sometimes whirl as they descend through the air. Tiny spiders will position themselves on the downwind side of a tree and spin several yards of silk into the wind. When they detect an upward pull they will release their grip on the tree and may be carried considerable distances on the air currents.

Spider silk will at times form a sort of halo around the sun. While individual strands will move steadily through the field of view, they scatter the light best at some critical angle, which forms the impression of a halo at a constant angular distance from the sun. Ashes falling from a grass fire plume (a common sight here in central Florida) look like a blizzard. Occasionally one will see an object moving very slowly, which must be at a great distance. I sometimes wish I had a telescope bore sighted with my binoculars so I could see them at greater magnification. These things must be the size of dinner plates. There are of course no mysteries in this region of the atmosphere, as it has been thoroughly explored for over a hundred years, but one sometimes sees something and wonders; What can that be?

Observing Techniques

WARNING: The phenomena described should be observed through dark sunglasses when the observer is located as described by the author. Readers are warned to never attempt the observations described here using binoculars or a telescope and to never observe the direct sun.

While I have used my Meade ETX 125 telescope and binoculars to observe sunlight artifacts, I do not recommend this as it is extremely dangerous. Observing even a small part of the sun through binoculars or a telescope can cause serious and even permanent damage to your vision!

Sunlight artifacts can be easily observed by simply looking near the sun while wearing dark sunglasses. Find a location where the sun is out of view behind a building or other solid object from where the sun's apparent movement will cause the location to become deeper in shadow For this reason, the morning the best morning location will be an overhang. In the afternoon the top of a building or a wall will serve well.

Use great caution to avoid looking at the direct sun. At first you probably won't see much but after several minutes you will see more and more.

Measurement

Winds usually vary in speed and direction with altitude sometimes fairly predictably. The most notable effect of this is that more distant objects will be moving more slowly and in a somewhat different direction than those that are closer. With detailed knowledge of current local wind conditions one could use drift rate and direction to roughly measure distance.

Photography

WARNING: Never look through the viewfinder of a camera pointed at or near the sun! Instead, simply point the camera toward the bright region near the sun from a shaded location. I have used this method with excellent results for many years. Editor.

I have tried on several occasions to photograph these objects, but the results have been rather uniformly disappointing.

Figure 1 shows several objects near the Sun. Note that none are well focused, so distance can’t be determined.

Figure 2 shows one bright, well focused object at about 30 meters (100 feet). This is little better than a guess, as the camera has a rather large depth of field. Both images were taken with a Cannon C-2500 digital camera.

Ordinary cameras (film and digital) have a smaller dynamic range than the eye. I often see half a dozen objects in view at one time, but the camera will pick up only the brightest one or two. One thing that helps is to stop down your camera several f stops. This will darken the sky and keep the objects from being overexposed. Another drawback of photography is that it completely eliminates any sense of depth. I have considered taking stereo photos, but this would require two nearly identical cameras which I don't have.

Safety Warnings

WARNING: EVEN THE BRIEFEST EXPOSURE TO THE CONCENTRATED RAYS OF THE SUN WILL DAMAGE YOUR EYES AND CAN CAUSE PERMANENT BLINDNESS!

When I was about 13-years old, I decided to look for sunspots with my 76 mm (3 inch) Edmund Scientific Newtonian telescope. I taped several layers of dark negative film over the eyepiece. When I found the target, the concentrated rays of the sun took perhaps half a second to vaporize the flimsy film in their way. Fortunately the hot gasses from the disintegrating plastic hit my eye, but, before I got my head out of the way, I witnessed a brief glimpse of what I thought was the brightest light in all creation. I closed the books on that experiment and have never been much enamored with solar observation since.

I relate this extremely dangerous experience to illustrate that looking near the sun is an inherently very hazardous activity.

Therefore, when looking for sunlight artifacts, wear dark sunglasses and look only toward the sun when solar disk is completely blocked by a solid object which cannot be inadvertently moved. Sit on a chair with a backrest so you cannot accidentally move your eyes into direct sunlight. Never try observations while standing. You may move enough so that your eyes receive direct sunlight.

Warning: Never use binoculars or telescopes to observe sunlight artifacts! Remember that binocular and telescope objectives are larger than your eyes! While your eyes may be shaded, the tops of your objectives may still be in sunlight. Also, if you elevate your instrument, the front end may move into sunlight. Even internal reflections can be harmful. The action begins several solar diameters from the sun anyway, and the sky within a couple of diameters is extremely bright.

If looking at the sky is uncomfortable, makes you squint or makes your eyes water you are looking too close to the sun. Reposition yourself.

Never try these fascinating observations without wearing dark sunglasses. Never look near the sun through binoculars or a telescope

Please be careful, use common sense and think before you observe.

I am eager to hear from anyone who tries these observations. Because I live in Florida, it would be particularly interesting to learn what can be seen by observers who live at northern latitudes on very clear, cold days. Please send comments to ulao@earthlink.net