The Ever Blue Sky....| Ever wondered why it's blue?

Well you might have been told that the sky is blue because it reflects the color of the sea and ocean.Well that's more or less a lie .Ever wondered why the sky is blue? Well, there is some pretty fun and simple science behind it! Continue reading to find out!

What is light?

Light is a type of energy. It is a form of electromagnetic radiation of a wavelength which can be detected by the human eye.^[1] It is a small part of the electromagnetic spectrum and radiation given off by stars like the sun. Animals can also see light. Light exists in tiny packets called photons. Electromagnetic waves can travel in a vacuum with or without contact with other particles. Light gets scattered whenever it hits a particle. Light travels at a speed of 299,792 km/sec (186,282 miles/sec). That's fast !

Colors of light

White Light is made up of three colors, Red Green and Blue

When you look at a light source, you may see that the light it's giving out is white. But actually white light is made up of many colors. A specially shaped crystal called a prism can split a beam of white light into the colors it is made up of. . These gradually shade into yellow, green, blue, indigo and violet. The colors have different wavelengths, frequencies, and energies. Violet has the shortest wavelength in the visible spectrum. That means it has the highest frequency and energy. Red has the longest wavelength, and lowest frequency and energy. The energy of the radiation and what happens to the beam after it hits an object depends on its wavelength and frequency. Wavelength is the distance between the tops (crests) of the waves. Frequency is the number of waves that pass by each second. The longer the wavelength of the light, the lower the frequency, and the less energy it contains.

Why Is the Sky Blue?

Gas molecules are smaller than the wavelength of visible light. If light bumps into them, it acts differently. When light hits a gas molecule, some of it may get absorbed. After awhile, the molecule radiates (releases, or gives off) the light in a different direction. The color that is radiated is the same color that was absorbed. The different colors of light are affected differently. All of the colors can be absorbed. But the higher frequencies (blues) are absorbed more often than the lower frequencies (reds). This process is called Rayleigh scattering. (It is named after Lord John Rayleigh, an English physicist, who first described it in the 1870's.)

The fact that the sky appears to be blue is that the gas molecules in the air absorb only the light waves with the highest frequency which is blue and then they radiate the same color that was absorbed.

Why doesn't the Moon Have a Blue Sky?

The answer to the question is pretty obvious. As you already may know, the moon doesn't have an atmosphere or simply it doesn't have air particles. Which means that light can easily travel to the moon's surface and then reflect back without being bombarded by any other particles which may cause it to stretch. 

What causes a Red sunset?

As less reaches you directly, the sun appears less bright. The color of the sun itself appears to change, first to orange and then to red. This is because even more of the short wavelength blues and greens are now scattered. Only the longer wavelengths are left in the direct beam that reaches your eyes.

The sky around the setting sun may take on many colors. The most spectacular shows occur when the air contains many small particles of dust or water. These particles reflect light in all directions. Then, as some of the light heads towards you, different amounts of the shorter wavelength colors are scattered out. You see the longer wavelengths, and the sky appears red, pink or orange.

Source : Science made Simple, the Wikipedia, NASA's Space Place
Author : Ethan Debnath