I say, Äúnearly at because there, AOS some starlight and there, AOS a little reflected light streaming in Moonshadows. On Earth shadows are flooded by various sources.
To understand these sources, try to imagine yourself as a small eyeball mounted on a back of an ant. As you walk through the shadow, imagine yourself looking around all the bright spots of light that shines on you, and not just the blue sky, but also white clouds, buildings or other bright objects . These spots of light determines the brightness temperature and the color of your shadow.
Here, AOS a shadow on a roof with a skylight. An ant walking across the shingles look and see a high cloud sky. But it would also see a large white wall just next to right, the bright side of the second corner. This white patch is brighter than the sky, and he pours light into the right half of the shade. Under the picture are samples from two areas of shade. You can see how the changes in cast shadow as light sources change backfill relative intensity.
On Earth, shadows tend to be blue only because normally They Aore thrown on surfaces that are looking to the blue sky. But be aware the doesn, AOT ant always see blue spots. Overcast, fill light is white. And sometimes the sky is small patch and other patches are bigger and stronger.
