Herschel inadvertently discovered “infra” red light, a brand-new part of the spectrum found just “below” red, reported in the first of his four papers on the subject. Herschel’s revelation was the astronomical equivalent of Antonie van Leeuwenhoek’s discovery of “many very little living animalcules, very prettily a-moving”††† in the smallest drop of lake water. Leeuwenhoek discovered single-celled organisms—a biological universe. Herschel discovered a new band of light. Both hiding in plain sight.
