How does color affect temperature? I've looked at every website, and I don't find anything to show which color is the hottest.

The answer depends on whether energy absorbed by an opaque object, or the energy emitted by  an object that is producing light, is being measured.

Visible light is composed of the colors of the rainbow. The acronym ROYBIV Is used to remember these colors in the order that they appear in the rainbow- red, orange, yellow, blue, indigo, and violet. Each color has a unique wavelength and frequency that determines its energy. Energy is directly...

The answer depends on whether energy absorbed by an opaque object, or the energy emitted by  an object that is producing light, is being measured.

Visible light is composed of the colors of the rainbow. The acronym ROYBIV Is used to remember these colors in the order that they appear in the rainbow- red, orange, yellow, blue, indigo, and violet. Each color has a unique wavelength and frequency that determines its energy. Energy is directly related to a color’s frequency and inversely related to its wavelength. Because red has the longest wavelength and slowest frequency, it has the least amount of energy. Likewise, because violet has the highest frequency and shortest wavelength, it has the highest energy.

The color that we see is the color that is reflected off of an opaque object. All other colors within the visible spectrum are absorbed by the opaque object. The energy absorbed is transformed into heat energy.

An opaque white object reflects all colors of visible light. Thus, an opaque white object absorbs none of the energy that corresponds the different color’s wavelengths and frequencies. Therefore, opaque items that are white in color tend to have low temperatures.

The opposite is true of opaque black objects. An opaque object that is black absorbs all colors of the visible spectrum. Thus all the energies associated with the colors’ wavelengths and frequencies are absorbed. Therefore, opaque black items are associated with higher temperatures.

Likewise, the temperatures of remaining opaque colors of the rainbow are associated with the sum of the energies of the colors that they absorb.

However, the opposite is true of the light emitted by an object. If a charged particle vibrates fast enough, light will be emitted. Temperature is a reflection of kinetic energy. Kinetic energy is the energy of motion. Therefore, higher temperatures are associated with more vibrations. Since white light reflects all colors of the visible spectrum, it is associated with the highest energy emission. Likewise, because black objects absorb all colors of the visible spectrum, it is associated with the lowest energy emission. This color/temperature relationship enables steelmakers to estimate the temperature range of heated metals based on the colors that they emit. Likewise, the temperatures of stars are also indicative of the colors they emit.