Looking at this photo that I just took, you might assume that it's a view of the stars and planets in the night sky, but it's not that at all.
It's a view looking down at the snow outside our breakfast window. The colored lights are sparkles of sunlight reflected and refracted internally inside snow crystals. Like a prism or a rainbow, the hexagonal crystals break the light into component wavelengths, giving the observer a variety of colors sampled from the rainbow: red, magenta, yellow, cyan, blue, and violet.
I took the photo with a digital SLR underexposed enough for the colored sparkles to register.
The conditions today are perfect for chromatic snow sparkles. It snowed three days ago, and has stayed below freezing since then, allowing the crystals to grow larger. This morning the temperature was five degrees Fahrenheit.
It appeared to me that the colored sparkles are most pronounced about 45 degrees away from the sun. In the photo above, that band passes through the right central part of the picture, with the sun coming from the left.
If you look at the sparkles on an angle farther away from the sun—or closer to the sun, the chromatic effect is much less noticeable.
Related previous post: Annular Highlights
Related topic: Sun dogs (rainbow effects on ice crystals in the sky near the sun)
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