Why our sky is blue, anyway? Humans have come to accept it as a natural part of every
day life. But what causes our atmosphere to appear blue? Why not green, or red, or
black, like outer space? The answer lies in earth’s atmosphere. It contains tiny
particles like gas molecules, water droplets, and dust motes, which serve as obstacles
to incoming light. These particles deflect sunlight and scatter it in all directions so
that light fills the sky. However, the shorter waves of the sunlight, at the blue end
of the spectrum, are scattered more than others, making our atmosphere blue.
Longer waves of orange and red have more energy, so they can move through atmospheric
particles with no problem. At sunset, when the sun moves on its downward path to
darkness, light must travel farther to reach the earth. Thus, it is the longer, more
energized red waves that can make the journey and reach the eye.