visible light
Why is this picture of a cat so colorful? No cat looks like this to the human eye. The picture was taken with a special camera that senses infrared light. This is a form of energy given off by warm objects. Areas that appear yellow are the warmest, and areas that appear purple are the coolest. The picture shows that the cats eyes are the warmest part of its head. Why cant people see images like this without a camera? The answer has to do with the wavelengths of infrared light. Its wavelengths are too long for the human eye to detect. In fact, the human eye can detect light only in a very narrow range of wavelengths, called visible light. Youll learn more about infrared light, visible light, and other forms of electromagnetic radiation in this chapter.