Johnny Mench, age 10s of Rochester  NY

 Why is the sky blue?

Andy had trouble with this most popular question. He wondered will all the others who asked it feel badly? He decided they would not, For it is a sensible question and those who ask sensible questions know that Andy can only select one person’s question at a time. They can read the answer and old Andy with a dozen or so more questions,

There was another problem. Very young people wonder why the sky is blue, But the simple question is not so simple to answer. It took a lot of smart grown ups to figure it out. Andy's job is to explain the complex reasons so that even his youngest readers can understand.

The blue sky is a trick of air and sunbeams. The sunbeams of course come from the sun. They fan straight out from the great star in all directions. Some of them flash across some 93 million miles  of empty space and fall upon the earth. They make the trip in just over 8 minutes.

In empty space the sunbeams have no color and the sky is black. We say they are made of white light   which is colorless, But, strange to says white light is a blend of all the colors of the rainbow. Each sunbeam is like a skein of bright threads. The light pulses along in little waves of energy. Each color travels on its own wavelength. In empty space  there is nothing to break up the skein of colors. The rainbow rays keep together and travel along as white light.

The sunbeam colors are red, orange, yellow  green, blue, indigo and violet   with countless shades between. The red rays have the longest wavelengths. The blues and violets have the shortest wavelengths. The crests and troughs of their little waves are closer together. The order of the colors is important  because each one from red to violet has a longer wave length. A piece of note paper is about as thick as 130 waves of red light or 300 violet waves.

The skein of colors is forced to show up a little and bend when it reaches the air way above the earth first bounced between tiny particle of of air, water vapor and midget specks of dust. The colors with the shorter wavelengths bend most easily. The blue and violet rays are bent and scattered all over to color the beautiful blue sky

The reds and golden colors have their chance at dawn at sunset: Then the sun is lower in the sky: Its rays slope and slice through a greater thickness of air. The sunbeams must pass through far more particles of gas and dust. There is enough bouncing around to bend the colors which travel on longer wavelength..

During the day, when the sun is high, only the short blue waves are bent and scattered to color the sky. At dawn and sunset, the long red! gold and even green rays are bent and scattered to paint the sky.