Sunlight Vs Neon Light Color Perception

Spectrum

• If you passed sunlight through a prism or a diffraction grating, you would create a spectrum or rainbow of color, because the sun emits light at many different wavelengths -- so much so that its spectrum is nearly continuous. Certain wavelengths, however, are absorbed by elements in the sun's atmosphere, and these create dark lines called Fraunhofer lines in the sun's spectrum. The sun's spectrum also contains unusually bright lines created by certain elements present in the sun.

Neon Spectrum

• Just as atoms of an element absorb specific wavelengths when they are cool, they also emit light at the same wavelengths when they are heated or energized. A neon light takes neon gas and runs an electric current through it, exciting the atoms of the gas so they radiate energy in the form of light. Unlike the sun, however, the neon lamp only emits light at a few wavelengths.

Limitations

• Your eyes can only detect electromagnetic radiation with wavelengths that fall inside a certain range -- from about 450 nanometers to about 750 nanometers, where a nanometer is a mere one-billionth of a meter. This range of wavelengths is often called the visible spectrum, because it's visible to humans. Some animals are able to perceive wavelengths outside of this range that are invisible to human eyes. Honeybees, for example, can see certain wavelengths of ultraviolet light.

Perception

• Sunlight seems white to you because it contains light of many different wavelengths, so your brain interprets it as "white." The neon sign, by contrast, emits light with a much more limited number of wavelengths; the wavelengths it emits that fall in the visible region of the spectrum are between 540 nanometers and 704 nanometers. Your brain perceives the combination of wavelengths emitted by the neon sign as reddish-orange.