At the edge of night in December, at mid-afternoon, Snæfellsjökull reveals one of the depths of the interaction between Earth and the Sun: light is not the illumination that humans “see” but a glow set up within objects, with differing intensities. Some of these intensities are what humans call “dark.” Well, by that standard, it’s all dark.

Snæfellsjökull from Ingjaldshóllkirkja

Everything in the image above is receiving the same radiation from the sun, but all are speaking it differently. Here you can see how they are sorted out by the human eye, and how the mountain glows with no more intensity and no less mystery than the dark foreground lava hills. Mountains have an inside. You can see that here, at the point at which the light and dark meet.