Rainbows have always fascinated human curiosity. The appearance of various colors in the sky out of basically nothing was something science had been trying to understand from a very early stage. It was when Newton discovered the visible spectrum that other scientist got some firm footing to explore the deep chasms on the edges of the visible spectrum.  The visible spectrum is just a small fraction of wide electromagnetic spectra which extends both above and below it, much beyond the ocular limits of the human eye. When scientists started experimenting with the infrared light, they realized that there was an immense potential in this particular band for seeing things much beyond the realms of visible spectrum, owing to its greater penetrability and thermal properties. Infrared imaging evolved as a result of continual effort towards harnessing the power of infrared.