Lewin's Challenge Image

[gpp]

I think the explanation is below:

http://www.wolkenatlas.de/wolken/wo06947.htm

Rgds,

GPP 8)

[Siege]

RJD's presumption of the source of light being a camera flash conflicts w/ the picture itself. The picture taker's shadow is present which would seem to rebut that argument.

I favor the source as either the Sun or one of those immense construction lights w/ the photographer between the light source and the subject surface. However, I favor the latter source as the one taking the photo appears to be standing up rather than leaning over. So, it would seem the picture is of a 'wall' rather than a 'floor'. The surface appears flat which can then rule out a tarp.

Methinks it's a composite marble or quartz type material like you see in hotels, banks, kitchen counters and the corona is the difraction of light resulting from the prism effect of the material's construction.

[lior]

I think the explanation is below:

http://www.wolkenatlas.de/wolken/wo06947.htm

Rgds,

GPP 8)

And there is an English version right here:

http://antwrp.gsfc.nasa.gov/apod/ap020417.html

[From Spain]

Is a kind of rainbow. Blue inside the circle, red outside.

To see a rainbow in the sky Sun must be low, near the horizont. The sun
must be at your back and raindrops on your front. The rainbow appears rounding an imaginary point at the opposite side from sun. The rainbows are a full circle. You see only a semi-circle because raindrops are up the ground. If you were in a airplane in right conditions could see a rainbow full circled.

He took the picture in a construction area in Massachusetts. The
ground, maybe some kind of concrete (He was in a construction area), had a microcrstaline compound that difracts the sunlight and returns back the light as rain drops difracts and returns back the sun light. That's why
his head and the camara is in the center of the rainbow. The bright area in
the center is due to There are many rays emerging at angles smaller than the rainbow ray, but essentially no light from single internal reflections
at angles greater than this ray. Thus there is a lot of light within the bow,
and very little beyond it. Because this light is a mix of all the rainbow
colors, it is white.

Spain

[zbvhs]

I think the phenomenon is called a "glory". I've seen them myself from airplanes. Around the shadow of the aircraft is a bright circle of light with one or more rainbow rings surrounding. I think the aircraft itself (or, in this case, the professor's head) serves as a crude pinhole in reverse and diffracts the light into the image shown. They only show up when distances are right and the pinhole is in focus.

Pinholes are fun. During a Solar eclipse one year. we had zillions of images of the eclipsed Sun on the ground under trees. Gaps between leaves formed pinholes that focused the Sun's image. We used small pocket mirrors to reflect Solar images onto the sides of buildings. Some claimed they could see Sunspots but I never did.

[Frank]

It is called a Glory. You can see glories sometimes looking down on a shadow as in the picture. It is light being defracted in a 21 degree ring around objects. Tiny ice particles in the upper atmosphere break down the light as a prism does.

[ralphlevy]

At a construction site there can be things up in the air. I suspect that there is a ball suspended from a crane high up behind the photographer. The diffraction of light passing the ball causes the light to bend toward the center causing the brighter center spot. The colors at the edge of the ring are from the bending of the light. The shadow of the ball is covered by the photographer's shadow.

[not a guest]

I agree with others that this effect is like the August 6th effect, maybe on some ground rock-salt or something in morning dew or that. BUT... what I thought was also unusual is that, if you notice, the person who took the picture looks a lot like it might be Beaker from the Muppets. ( lol )

Does anyone else see the resemblance?

[tlevangi]

I think it's the phenomena know as "the glory" where small droplets of water diffarct the sunliht backwards towards the sun. Ref:
http://antwrp.gsfc.nasa.gov/apod/ap040806.html
In this case, he's behind a construction tarp which has some condensation on it, and instead of the sun, the droplets are diffracting the light back towards the camera's flash.

[Guest]

Is it because you used a flash in daylight, flooding natural light with white light causing separation of the spectrum around the edges where the intensity of the white light is at it's dimmest?


Mike Bowles

[BlueImmue]

It seems to me that this is polarized light analysis at its best! The bright light in the middle is so highly reflective that the material's wavelengths are dispersed at poles and creates this blinding light. The colored rings around the image is where the material is thinner, therefore more light can pass through at the poles, creating polarized light poles when lined up at 90 degree and 180 degree radii, causing the "rainbow" affect. Maybe it's some sort of oil substance on the ground? Also, with the shadow of the person standing there, there is sort of an eclipse effect.
Right?

[mitch]

I assume that it is a diffraction pattern through a small circular hole in a beam. The longer wave lengths defract more and interfere in a clasic circular diffraction pattern, that is why it goes from blue to red.

[tlevangi]

I think it's the phenomena know as "the glory" where small droplets of water diffarct the sunliht backwards towards the sun. Ref:
http://antwrp.gsfc.nasa.gov/apod/ap040806.html
In this case, he's behind a construction tarp which has some condensation on it, and instead of the sun, the droplets are diffracting the light back towards the camera's flash.

[tom butt]

I am a former USAF pilot and I agree with the 707 pilot, and many others, who say that the image is a "glory."

The question that hasn't been answered is "What is the object between the sun and the ground that is causing the beautifully circular image?" An aircraft creates an image in it's own shape. (Pretty much. I too have seen many of them on the surface of the clouds below while flying across the Pacific.)

My guess is that it is some large spherical object, such as a wrecking ball, suspended exactly in front of the sun from the professor's perspective. The professor is standing in the shadow of the wrecking ball, hence the darker shadowed area, and the bright center along with the colors come from the "glory" effect.

After all, he discovered it at a construction site!

[Peter Thomas]

My GUESS is the professor is standing in a shaft of light cast by a circular aperture at some distance. The rings are edge diffraction. After passing through the aperture, the edge of the wave wants to diffract outward, reds being bent out more than the blue. We see this in telescopes with an obstruction except the wave bends inward the fill the hole in the lightwave created by the obstruction.

[Guest]

I have an answer that will explain the bright center, the color order in the ring, and the overall appearance of the image. The photographer was taking a picture of a concave spherical, specularly reflecting surface. That is a mirrored surface kind of like a shaving mirror. The sun was directly behind the camera. The camera was focused on the reflecting surface. The concave reflecting surface created an image of the sun that was formed between the mirror surface and the lens. This created an out of focus image of the sun on the film/detector. The image of the sun would then be focused by the camera lens behind the film. The camera lens exhibits chromatic aberration which causes the blue light to be focused in front of the red because blue light refracts more than red light. Since the camera lens is focusing the image behind the detector, a blue ring would be formed inside the red ring. The background appears bright when the sunlight fills the pupil of the camera lens. It appears dark when it vignettes the camera pupil. There is dust and debris on the mirrored surface which causes scattering in those areas. This is why parts of the darker area appear brighter.

[damico.1@osu.edu]

This could be a simple plash picture of wet pavement which has some
petroleum product (such as gasoline) floating on the water. The gasoline gives the rainbow effect at the edge of the puddle.

[sfbriz]

It is clearly the work of angels, spreading the light on a worthy soul. The man taking the picture is about to die and we see his aura emanating about his head and shoulders in preparation for his transformation into a being of light.

Either that or photoshop.

[Derek Dahlsad]

I agree with the aperture people...

The range is small (<10 feet) so it's not the Glory -- the Glory occurs by scattering of particles in the air over a large space., all at an angle directly back at you, by particles in the air in front. There's not enough space between the photographer and the source to be enough particles to scatter that much light (and it's a lot of light!) Also, there is no haze between the photographer and the circle.

The circle appears to be on the ground a few feet in front of the photographer, so it's not quite parallel to him, not quite perpendicular. The glory appears in space parallel to the viewer (it looks vertical out from you), or at least parallel to the apparent location of the sun. If the photographer walked ten feet to the left and ten feet forward, the circle will appear to be a long oval. The photographer is standing directly in the path of the projected light, and as such it appears to be a circle directly in front of him. This also leads away from the Glory theory: the light at the photographer's feet is at a steeper angle than the light further away, not some uniform angle caused by particle diffraction.

The light projected is uniformly regular, so it's being projected from a source quite a ways behind the photographer, a very small one (large projection sources will blur closer to the source, and widen and darken further away).

Ever run a slide projector or movie projector without a film? You'll see this same effect. Because there's a thickness to the aperture, it defracts light differently and causes the rainbow at the edges. It's also possible small airborne particles would cause it, but the light in the center is too bright and white to be affected by that.



Explanation of the color sequence:

There's thickness to the aperture (or something else around the edge, like a rough drilled hole). In the middle, there's no big effect, because the light's all scattered in random ways and wavelengths. At the edges however, the hole's permieter causes light to be more polarized and filtered, bending the light slightly and causing the red to be bent more away from the circle, the blue less so.

BTW: At that range, a camera flash would wash out the shadow, or at least make it less sharp. If so much light is coming off the flash that it reflects off the ground and enough comes straight back at the camera, that's one heck of a flash! If that happened, there'd be no shadow; if there's that much of a shadow, then the flash didn't put out enough light to make the circle.

(sorry for all the editing; things keep coming to me!

[monty]

I believe it is the result of the sunlight being defracted by the hair (possibly gel coated) of the individual casting the shadow.

[Mesophelioma Whoopa]

It looks like the picture is of water flowing over sand, (possibly at a beach) taken from directly above the area with a flash. The center of the light burst originates roughly around the top right corner of what appears to be a camera in the shadowy figures hand.

[FABC]

The light ring comes from behind the photographer and the light material inside the ring and portions outside are a dust contol material that has been swept or squeeged away from outside the ring in a rather amateurish fashion

[ArtStithem]

I'm amused by all the overly complex explanations, which are almost certainly wrong. The most logical explanation is that the picture was taken through water mist during or shortly the construction area was sprayed for dust control and the image is a Glory.

I don't know if the has anything to do with it or not, but I'm going to try it out. He used a digital camera, which has an inherent defraction grating caused by the pixel arrangement. It is also possible that he used a circular polarizing filter which contributed to the effect, although I would think that would suppress rather than enhance this phenomena. In any case I'm making this overly complex as well. However, I can test my hypothesis.

[Derek Dahlsad]

I just realized something that debunks the aperture theory:

The photographer's shadow extends outside the circle, without being significantly darker or brighter than inside the circle. The shadow isn't being cast by light pouring through an aperture; it comes from another source.

Which lends more to the answer given by Emma; that there's reflective particles on the ground bouncing light back at the photographer. The shadow isn't diminished (he's still blocking the same amount of light on all parts of the ground), but the center appears brighter because of the light reflected back at the photographer.

[Bubba from LA not L.A.]

Not being too bright, it looks like what happens when too much light gets through a viewfinder on a SLR camera small apeture at the front, larger at the rear (going backwards through the camera) with multiple glass interactions and at least two glass/air interfaces... but what do I know..