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Comment by mannykannot | Hacker News Reader

I get the impression that this shows a sort of 'double-dip' sunset where, just before it goes completely dark, it brightens briefly (and the converse at dawn.) It seems to be there when I step through the frames. Can someone say if this is an illusion (or a personal delusion on my part), a meteorological effect, a camera sensitivity-adjusting effect...?

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It doesn't seem to change in intensity, but in what is illuminated. While high, sun itself appears bright, when dropping lower the things lighted from the side, and at the end scattered light at the horizon.

Thank you for your reply. I have to admit that I was paying attention to the sky, rather than the surface. The effect I am referring to can be seen in the transition from the 0:05 and 0:06 time in the video, and I see that what I perceive as a brightening of the sky is also accompanied by a brightening of the nearest structure. If I am not mistaken, the sun is already below the horizon during this sequence.

Of course, if this is just a delusion on my part, what I have written will make no sense to you!

I see what you see but I'm not sure whether it's a real effect or just an artifact of the photography. There must be some adjustment of exposure to have both the daytime and the nighttime well exposed, so it may just be the changing exposure that makes the brightness of the horizon non-monotonic.

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