All visible light is radiation. However, not all radiation is visible light. In fact, (as we’ve all learned in high school physics) the term “light” applies to far more than the pretty colors we call the visible light spectrum. Our eyes are equipped to see a range of wavelengths, from the long waves of red light to the short waves of blue and violet. Just outside of our visible spectrum is infrared light (on the low energy side) and Ultra Violet light (on the high energy side). An interesting side note… our eyes are much better suited to detecting light at longer wavelengths, toward the red end of the spectrum. This is why stop signs and traffic lights are red, instead of blue or purple.
