The technical details of rainbow formation were first analyzed by Isaac Newton in 1665. His brilliant optics work concerning reflection and refraction certainly does not detract from the beauty and promise of the rainbow. On the contrary, Newton's scientific insights show the marvelous complexity of creation. Never again will the waters become a flood to destroy all life. A rainbow occurs when raindrops and sunshine cross paths.
Sunlight consists of all the colors of light, which add together to make white illumination.
When sunlight enters water drops, it reflects off their inside surfaces. While passing through the droplets, the light also separates into its component colors, which is similar to the effect of a glass prism. Each falling water drop actually flashes its colors to the observer for just an instant, before another drop takes its place. A rainbow is usually seen in the opposite direction in the sky from the sun. The rainbow light is reflected to the eye at an angle of 42 degrees to the original ray of sunlight.