Why is the Sky Blue?: A Scientific Explanation

Every day, we wake up, go outside and look around us. We look up at the sky and notice the baby-blue hue that is there. Every night, we look up and notice the navy-blue backdrop for the stars, but how often do any of us question why it is, in fact, a shade of blue we are seeing?

In order to understand why the sky is the color that it is there are a couple of factors that should be taken into consideration. The atmosphere, light waves, the different colors of light, and the light in the air all have to be taken into consideration when approaching this question.

The atmosphere is composed of different gas molecules and many other materials, but it mostly contains oxygen and nitrogen. Water vapor, ice crystals, and drops of water are also a common thing in the atmosphere. The atmosphere is very dense where it meets the earth and it gets thinner as it blends into space.

Light is a form of energy, and this form of energy moves and radiates throughout the universe in the form of waves. Light travels in waves of vibrating magnetic and electric fields. Light waves are part of a larger thing known as the electromagnetic spectrum; the spectrum is composed of many vibrating electromagnetic fields.

There are many different colors of light. Visible light is the part of the spectrum that humans can see. Light in your home from your lamp or the light from the sun in the sky may appear to be the color white, but this is not so. White light consists of many colors; this is apparent when there is a rainbow in the sky.

Light travels through the air in straight lines. Light will go straight until it bumps into something and its' path is disturbed. Light will do different things when it comes in contact with different things. When light hits a large object it bounces off or is reflected in a different direction. When light hits a gas molecule some of the light is absorbed and the molecule will radiate and release some of the light into a different direction later on.

So now we know all of this stuff, but we still do not know why the sky is blue. The sky is blue because the different wavelengths of the different colors of light are absorbed differently. The shorter wavelengths, which happen to be blue, are absorbed more easily by the gas molecules, and are thus radiated throughout the sky. The scattered blue light released by these gas molecules are coming in all different directions, and this makes the sky look blue.