Walking the dog in the evening last May, I saw this bright spot in the sky. The sun had just set and quite a few folks had also noticed it.

I had never seen an optical display after sundown, yet could never think of a reason for this. Indeed, there is no physical reason that some ice-crystal reflection and refraction effects should not be visible after sundown. So, I had simply decided my lack of seeing them was simply due to not having the sun as a good reference point to locate the relatively subtle displays.

This case was not subtle. Indeed, as you can see by the people in the picture, even the "ice-display" novices had noticed.

I will keep this brief, but here is a very crude description of what is happening. The image at the right half is with the contrast cranked up high to help make it clearer.

--JN