He was studying the temperature of different colors by moving a thermometer through light split by a prism .
The first discovery of electromagnetic radiation other than visible light came in 1800 , when William Herschel discovered infrared radiation .
William Herschel was studying the temperature of different colors by moving a thermometer through light split by a prism .
The first discovery of electromagnetic radiation other than visible light came in 1800 , when William Herschel discovered infrared radiation .