What's Hot, What's Not?

This camera is sensitive to infrared light, an invisible form of energy given off by objects and people alike. Warmer objects radiate more infrared light than cooler objects do, and appear brighter on the projected image.

The aluminum table in front of the bench at this exhibit is a good thermal conductor: heat moves through it quickly. When you touch a shape, heat flows easily from your hand to the metal, cooling your skin and creating a dark pattern. As your skin warms, the pattern fades.

The various panels behind the bench at this exhibit reflect some forms of energy better than others. Acrylic reflects visible light but not infrared radiation, so your reflection doesn’t show up on the screen. The unpolished copper reflects visible light poorly, so you can’t see yourself in it. But copper does reflect infrared rays—which is why you can see reflected images in the copper panel when you look at it on the screen.

Infrared cameras are used in some night vision systems, in industry, astronomy, and to help find heat leaks in insulated homes.

Like the camera in this exhibit, rattlesnakes can “see” infrared light—but not with their eyes. Instead, they use infrared-sensing organs called pits, found between the nostril and eye. Being able to sense infrared light helps rattlesnakes and other pit vipers track their warm-blooded prey.