The discovery of infrared

While driving over to the bowling alley yesterday, I heard a report on NPR about the discovery of the infrared spectrum. It's a cool story.

William Hershel, a German-born British astronomer (1738-1822) looked at the spectrum of light projected by a beam passing through a prism. He wondered if the different colors had different temperatures, so he placed a thermometer within each of the primary colors. After he found that there was a range of temperatures from blue (cool) to red (warm), he put the thermometer just beyond the red color to get a "control" temperature for the room, and discovered to his astonishment that where there was no apparent color, the temperature was actually warmer than it was in the red band. This was the first evidence that there was an infrared wavelength.

Image credit here.