Episode 1 of 2
Filter experiments reveal invisible heat
- When
- 1800
- Where
- Herschel's location during the experiments
While testing coloured sunlight filters in early 1800, Herschel noticed filters of different colours generated varying amounts of heat.
In early 1800, Herschel was testing different filters to pass sunlight through, and noticed that filters of different colours seemed to generate varying amounts of heat. In the course of these investigations, he discovered infrared radiation, a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer.
Sources
- William Herschel Wikipedia, revision of 2026-09-26
- Infrared Wikipedia, revision of 2026-09-24
Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.