John Herschel

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Sir John Frederick William Herschel, or more simply John Herschel, was a man of many talents, including: mathematician, botanist, astronomer, chemist, experimental photographer, and inventor. He was born on March 7, 1792 and died on May 11, 1871. He was the son of famed astronomer Sir William Herschel. Photography and the actinometer(instrument used to measure the heating power of radiation) are among his inventions. He originated the use of the Julian day system in astronomy, named seven moons of Saturn and four moons of Uranus, as well as investigating ultraviolet rays.

Herschel began his mathematical education at Eton College and St John’s College, Cambridge, graduating in 1813. His interests soon turned to astronomy and he built a 460 mm reflecting telescope 6.1 m focal length that same year. Between 1821 and 1823 he re-examined the double stars cataloged by his father. In 1826, this work earned him the Gold Medal of the Royal Astronomical Society and the Lalande Medal of the French Academy of Sciences. He was made a Knight of the Royal Guelphic Order in 1831. Later that same year he proposed methods of scientific investigation that set forth the relationship between observation and theory. He thought the highest scientific goal should be understanding through inductive reasoning and finding a single unifying explanation for a phenomenon. He published the General Catalog of Nebulae and Clusters in 1864. This work was a compilation of his and his father’s observations, with an expanded version being published posthumously. The final work cataloged 10,300 double and multiple stars.

Another area of note that Herschel made numerous important contributions to was photography. He made improvements in photographic processes, particularly in inventing the cyanotype process and the chrysotype, each a precursor of the modern blueprint process. He experimented with color reproduction, noting that rays of different parts of the spectrum tended to impart their own color to a photographic paper. He is also credited with having discovered the platinum process, later developed by William Willis. Herschel also coined the term photography in 1839 and applied the terms negative and positive to photography. He discovered that sodium thiosulfate was a solvent of silver halides, noting that this solution could be used as a photographic fixer(make pictures permanent). This led to the advances in photography used by Daguerre. As you can see, John Herschel was a true Renaissance Man in his interests and contributions to that which he studied.

We have written many articles about John Herschel for Universe Today. Here’s an article about John Herschel’s father, Sir William Herschel, and here’s an article about the Moons of Uranus.

If you’d like more info on John Herschel, check out these articles:
John Herschel’s biography
John Herschel (1792-1871)

We’ve also recorded an entire episode of Astronomy Cast all about Ultraviolet Astronomy. Listen here, Episode 134: Ultraviolet Astronomy.

Source:
http://messier.seds.org/xtra/Bios/jherschel.html

Tagged as: John Herschel, Julian day system, ultraviolet rays