In infrared guidance, what is the difference between hot and cold targets?

• A. A hot target emits more infrared energy than a cold target
• B. A cold target emits more infrared energy than a hot target
• C. Infrared energy is the same for hot and cold targets
• D. The difference is only in color

Answer: (C)

In infrared guidance, the amount of infrared energy a target radiates is determined mainly by its temperature. A hotter target gives off more infrared radiation than a cooler one (assuming emissivity is similar). The seeker senses this energy and uses the brightness, or contrast, on the infrared image to lock onto and track the target. Visible color isn’t what the infrared sensor cares about—the detector responds to heat, not color—so the key difference between hot and cold targets is the level of infrared energy they emit, with hot targets appearing stronger on the IR sensor.