subject: Blue Heaven: Why The Sky Is Blue [print this page] That the sky is a beautiful shade of blue is one of those irrefutable facts of life that the vast majority of humankind generally accepts. But while most of us would take this for granted, there are still others who may actually be curious as to the true nature of this phenomenon.
There are among us those who at some point are sure to have contemplated "why is the sky blue?" Is there a reason for this, an explanation, or could it all have been merely coincidence that the sky would be of such a color? Could the sky have been any other hue? Red, perhaps? Yellow, green, purple or pink, even?
The truth is that there is actually a scientific explanation for why is the sky blue. This is because of a phenomenon known as "Raleigh Scattering," wherein light is scattered off of the molecules present in the atmosphere. While most of the wavelengths of light, most especially the longer wavelengths, can easily pass through the atmosphere as light travels through it, shorter wavelengths are usually unable to do so and instead end up getting absorbed by gas molecules which absorb all the color from light. Certain colors are easily absorbed more than others, with blue being one of the readily-absorbed hues of light.
To have a clear picture of just why is the sky blue, one should take into account what takes place when the gas molecules in the atmosphere absorb blue light. Once it is absorbed, blue light is dispersed in numerous directions all across the sky. Although sunlight is actually made up of a wide array of colors, blue light is so spread out throughout the sky that it is seen in that color regardless of where one's location is or in what direction one would choose to look at it.
One may notice that the color of the sky close to the horizon actually looks paler compared to the shade of blue in the portion of the sky directly above. The reason for this is because the farther away that light is situated the more air it has to pass through before it arrives at one's line of sight. As the blue light in the distance gets dispersed in various directions, very little of it reaches one's view, thus giving the horizon a very pale shade of blue, and even white at its palest.
But even though the sky appears blue when viewed from the ground, it in fact appears black when seen from space. This is because there is no atmosphere present in outer space for sunlight to scatter through. If the Earth had no atmosphere, like on the moon, everyone would see the sky as colored black (of course, no one would even survive if the Earth had no atmosphere, but that's another matter entirely).
It has been asked in rhetorical and philosophical terms, but the question "why is the sky blue" has long been answered in scientific terms. It's another one of life's little mysteries that has been solved, but this shouldn't stop us from dreamily gazing at the sky and look on in awe at how nature and science works in fascinating and rational ways to provide us with such a breathtaking backdrop to our everyday existence on this wonderful planet.
