* Astronomy

Johann Wilhelm Ritter (16 December 1776 - 23 January 1810) was a German chemist, physicist and philosopher.
Many of Ritter's researches were guided by a search for polarities in the several "forces" of nature, and for the relation between those "forces" two of the assumptions of Naturphilosophie. In 1801, after hearing about the discovery of "heat rays" (infrared radiation) by William Herschel (in 1800), Ritter looked for an opposite (cooling) radiation at the other end of the visible spectrum. He did not find exactly what he expected to find, but after a series of attempts he noticed that silver chloride was transformed faster from white to black when it was placed at the dark region of the Sun's spectrum, close to its violet end. The "chemical rays" found by him were afterwards called ultraviolet radiation.
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