What objects emit infrared light? What technology exploits this?
Infrared radiation is a type of electromagnetic radiation, as are radio waves, ultraviolet radiation, X-rays and microwaves. Infrared (IR) light is the part of the EM spectrum that people encounter most in everyday life, although much of it goes unnoticed. It is invisible to human eyes, but people can feel it as heat.
When an object is not quite hot enough to radiate visible light, it will emit most of its energy...