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Objects can either emit light and heat of their own, or they can reflect light and heat from other sources such as the Sun. Most objects (except light bulbs) do not emit light of their own; they only reflect the light that hits them. The COLOR of an object is determined by which colors of light it reflects; red objects reflect primarily red light, while blue objects reflect more blue light. White objects reflect all colors, while black objects don't reflect any colors very well.

Which is why a black object gets warmer in the sunlight than other colors do; the black object reflects very little of the sunlight that hits it, and instead absorbs the light energy. Where does the absorbed light go? Noplace; it becomes heat and is retained within the object. So black clothing helps you to absorb heat on a cool day.

That's why, if you look at photos of hot air balloons, the very top of the balloon is often black; to absorb solar energy from the Sun, and transfer it into the balloon which will heat up the air within. Black balloons absorb enough heat from the Sun to save several percent in fuel costs!