Human beings cannot perceive light in the infrared wavelengths unlike some snakes. However, we can build devices such as cameras that detect light in the infrared and then color code the images so we can see them. I found one such camera at the NASA Goddard Space Flight Center in Greenbelt, Maryland. In the video below, white and red are the warmest while purple and blue are the coldest. Notice how my mustache and glasses are cooler than the surrounding areas.