The Readers Photo Challenge will give you the chance to embrace your dark side because this month’s subject is “shadows.” You ...

Shadows are created when an object blocks light from the Sun or another light source. When the light can't pass through the object, it makes a dark spot on the ground or wall behind it ...

At two times of the year, for points inside the tropics, the Sun's rays are perpendicular to the ground at local noon, destroying shadows on vertical objects. When does it happen? Every place in ...