Sir William Herschel Discovers Infrared Radiation.
William Herschel detects
infrared light while measuring the temperatures in the colors of the
spectrum created by passing sunlight through a prism.
Herschel noticed that the temperature increased from the blue to the red
part of the spectrum. He then measures the temperature in the region just
past the red where there is no visible light, and to his surprise, this
region registers the highest temperature of all. This experiment shows
for the first time that there is light that we cannot see with our eyes.
Infrared becomes the first form of invisible radiation to be discovered.
Herschel's experiment also shows that the Sun is a source of infrared light.