Optical phenomena in nature are generally caused by interactions between sunlight and the atmosphere, clouds, water, dust and other particles and materials, animals and plants, and even objects, both natural and man-made. From sunsets to the rainbows, passing through the blues and green of the oceans and the astounding variety of colors of animals and plants, nature unveils many examples of optical phenomena.

Some are a consequence of the dual behavior of light as a particle and wave. Some are easily observable, such as rainbows, and others can only be observed and measured by precise scientific instrumentation, such as the curvature of a star by the sun during a solar eclipse, demonstrating the curvature of space as predicted in the theory of relativity.