Air molecules and dust particles in Earth's atmosphere scatter sunlight into the various colors we see in the sky. We see blue during the daytime, when the sun is more directly overhead because of blue's shorter wavelength, which scatters and spreads more prominently than the other colors. As we see the sun lowering to the horizon, though, sunlight must pass through more of Earth's atmosphere, making it harder for blue's shorter waves to pass and easier for the longer waves of orange and red to appear.
Every object has a surface, and every surface has a chemical makeup that determines its color. Each color we see in an object corresponds to a different wavelength in the visible light spectrum. These light-bearing chemicals, called pigments, absorb some wavelengths while reflecting others, which we see in the form of color. Three classes of pigment help determine an object's color: chlorophylls, a greenish pigment, carotenoids, red, orange or yellow pigments and phycobilins, red and bluish pigments.
An objects surface structure can produce some of the most fascinating manifestations of color, called iridescence. For example, peacocks, certain species of fish and the morpho butterfly all have unique surface structures that interfere with light in such a way that colors dazzle and glimmer when light hits from different angles. The morpho butterfly's microscopic surface ridges intensify blue color while canceling out others, giving it a brilliant blue appearance.
The way nature separates color from white light has inspired scientists and others to imitate this phenomenon through technology. Some methods may be more crude, such as when a photographer smears petroleum jelly over a glass color filter to reduce contrast and sharpness in a photo, or more intricate, as in the case of food scientists creating artificial pigments for coloring foods and drinks.