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William Herschel



Wikipedia : William Herschel


Frederick William Herschel,[1] KH, FRS  German: Friedrich Wilhelm Herschel;


15 November 1738 – 25 August 1822 


was a German-born British[3] astronomer, composer and brother of fellow astronomer Caroline Herschel, with whom he worked.


Born in the Electorate of Hanover, Herschel followed his father into the Military Band of Hanover, before migrating to Great Britain in 1757 at the age of nineteen.


Herschel constructed his first large telescope in 1774, after which he spent nine years carrying out sky surveys to investigate double stars.


Herschel published catalogues of nebulae in 1802 (2,500 objects) and in 1820 (5,000 objects).


The resolving power of the Herschel telescopes revealed that many objects called nebulae in the Messier catalogue were actually clusters of stars.


On 13 March 1781 while making observations he made note of a new object in the constellation of Gemini.


This would, after several weeks of verification and consultation with other astronomers, be confirmed to be a new planet, eventually given the name of Uranus.


This was the first planet to be discovered since antiquity and Herschel became famous overnight.


As a result of this discovery, George III appointed him Court Astronomer.


He was elected as a Fellow of the Royal Society and grants were provided for the construction of new telescopes.


Herschel pioneered the use of astronomical spectrophotometry, using prisms and temperature measuring equipment to measure the wavelength distribution of stellar spectra.


In addition, Herschel discovered infrared radiation.[4]


Other work included an improved determination of the rotation period of Mars,[5] the discovery that the Martian polar caps vary seasonally, the discovery of Titania and Oberon (moons of Uranus) and Enceladus and Mimas (moons of Saturn). Herschel was made a Knight of the Royal Guelphic Order in 1816.


He was the first President of the Royal Astronomical Society when it was founded in 1820.


He died in August 1822, and his work was continued by his only son, John Herschel.


William Herschel
William Herschel01.jpg
1785 portrait by Lemuel Francis Abbott
Friedrich Wilhelm Herschel

15 November 1738
Died 25 August 1822 (aged 83)
Slough, England, UK
Resting place St Laurence's Church, Slough
Residence Observatory House
Nationality Hanoverian; later British
Known for
Spouse(s) Mary Baldwin Herschel
Children John Herschel (son)
Awards Copley Medal (1781)
Scientific career
Fields Astronomy and music





Discovery of infrared radiation in sunlight


On 11 February 1800, Herschel was testing filters for the Sun so he could observe sunspot.


When using a red filter he found there was a lot of heat produced.


Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum.


This thermometer was meant to be a control to measure the ambient air temperature in the room.


He was shocked when it showed a higher temperature than the visible spectrum.


Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum.[96][97]