Radiation emitted by hot bodies have the color:

Explanation

Its color depends only on its temperature. By definition, a black body does not reflect light, and only emits light by radiation because of its temperature, so at zero degrees it's totally black. As it it gradually warms up, it emits radio waves and then infrared waves (cant be seen). As it warms further it begins to glow red the way a heating coil glows red when heated. As it continues to warm, it glows orange, yellow, then (at about 6,000 kelvin like the surface of the sun) white because it is now emitting all the wavelengths in the visible spectrum. At higher temperatures it continues to glow white even though it is now also emitting X-rays and gamma rays (along with radio, infrared, visible, ultraviolet, and X-rays).