Pasadena, California: c. 1926 Astronomers Edison Pettiy, (L) and Seth Barnes Nicholson of the Mt. Wilson Observatory have made the first systematic infrared observations of celestial objects using a thermocouple and a galvanometer. NIcholson is observing the thermocouple while Pettit watches the galvanometer.
Crédito:
Album / Universal Images Group / Underwood Archives/UIG