Why Do Bright Lights Have Rays

[peter.ell]

I'm not sure if anyone knows, or if this really is a physics question, but I was wondering why bright lights always seem to have rays emanating from them.

What I mean by this is that bright lights, such as the sun or a car's headlight, always seem to radiate light in visibly distinct bright lines encircling the light source. This is apparent to our eyes as well as cameras, but what actually causes the light to radiate in spatially separated lines of light rather than circularly and uniformly?

Take a look at this for an example of what I mean: http://www.homesolarinfo.com/image-files/sun-clouds-sky-picture2.jpg

Thank you!

 

[Drakkith]

Hrmm, that looks a bit like a Diffraction Spike. See here for more info.

http://en.wikipedia.org/wiki/Diffraction_spike

I believe they are most likely due to similar effects. The atmosphere and your eye produces "artifacts" or whatnot of the light that are more pronounced the brighter the source is.

 

[AtomicJoe]

That is a photograph though. Not quite the same as an eye.

Actually looking at it it looks a bit like a retina, could they be produced by minor imperfections in the aperture of the camera?

 

[Drakkith]

That is a photograph though. Not quite the same as an eye.

Actually looking at it it looks a bit like a retina, could they be produced by minor imperfections in the aperture of the camera?

I believe your eye produces diffraction effects as well. I don't know any details though.

 

[Borek]

Eye and camera are not that different. You have a lens, a diaphragm, and a light sensitive surface. There is a difference in a diaphragm shape - that makes "rays" in the camera much more geometric, but other than that there is no reason for substantially different mechanism in both cases.

Or at least that's how I see it.