What Color is Your Shadow?

Reproduced with the permission of Lewis Carroll Epstein, the author of "THINKING PHYSICS".

On a clear and sunny day you are on snow and look at your shadow. You see that it is tinted.

a) red
b) yellow
c) green
d) blue
e) not at all

Answer to Think Puzzle:

The answer is: d. The part of the snow in direct sun shows the color of the sun: yellow white. The snow in your shadow gets no direct sunlight, but is illuminated by light from the blue sky. Perhaps it is the blue color of shadows that makes people associate blue with cold.