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Today I was waiting in the car park and noticed the very bright sunlight reflecting off the car near me, I was just being bored and noticed when I make a small slit/hole with my fingers by curling them like a telescope, when looking directly into the glare, at a precise certain angle I could see a rainbow halo/streak. But when I slightly moved my fingers, even a cm the rainbow disappeared and just became white light again??? (I will say this was pretty hard to do, I had to get a precise certain angle, looking directly into the light and adjust my hand scope accordingly). I could do this in both eyes, I'm 19 and still learning.

Any brilliant minds with an answer?

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  • $\begingroup$ I'd be great if you had taken a picture. $\endgroup$
    – stafusa
    Commented Dec 16, 2017 at 9:24
  • $\begingroup$ it just looked like when a camera hits the sunlight a certain way. $\endgroup$
    – Mendes550
    Commented Dec 16, 2017 at 9:38
  • $\begingroup$ An additional question might be: why did this interference effect appear when looking at reflections of the sun on cars, but not when looking at the sun directly? The answer is: reflections on a convex surface are better point sources. The angular diameter of the sun is 0.5°, which is rather large for a point source in an interference experiment. $\endgroup$
    – jkien
    Commented Dec 17, 2017 at 12:34

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This is awesome that you have noticed that!=)) Cool! This is diffraction on a slit.

In short, the sunlight has a complicated content - it contains a lot of waves oscillating with different frequencies in itself. Basically, the white light we see coming from the Sun contains all the visible spectrum +UV, IR and a bit of heavier stuff.

Now, when this kind of light approaches the slit, different frequencies bend under different angles on its edges, so that it forms fringes. Those fringes get to your eye and you see the rainbow=)

enter image description here

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  • $\begingroup$ I've noticed if I create a pinhole with my hand like a telescope, a few cm's away from my face, and then start looking through it directly into a bright bulb, and unfocus my eyes, at a certain angle I am also able to see the same thing, is this also slit diffraction? How come I'm not able to see it without a hand scape? $\endgroup$
    – Mendes550
    Commented Dec 16, 2017 at 11:54

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