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Frederick William Herschel, KH, FRS (/, -/; German: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British 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.
1785 portrait by Lemuel Francis Abbott
|Born||Friedrich Wilhelm Herschel
15 November 1738
Hanover, Brunswick-Lüneburg, Holy Roman Empire
|Died||25 August 1822
Slough, England, UK
|Resting place||St Laurence's Church, Slough|
|Nationality||Hanoverian; later British|
|Spouse(s)||Mary Baldwin Herschel|
|Children||John Herschel (son)|
|Awards||Copley Medal (1781)|
|Fields||Astronomy and music|
Herschel constructed his first large telescope in 1774, after which he spent nine years carrying out sky surveys to investigate double stars. The resolving power of the Herschel telescopes revealed that the nebulae in the Messier catalogue were clusters of stars. Herschel published catalogues of nebulae in 1802 (2,500 objects) and in 1820 (5,000 objects). In the course of an observation on 13 March 1781, he realized that one celestial body he had observed was not a star, but a planet, 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 as a diagnostic tool, using prisms and temperature measuring equipment to measure the wavelength distribution of stellar spectra. Other work included an improved determination of the rotation period of Mars, 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). In addition, Herschel discovered infrared radiation. 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.
Early life and musical activitiesEdit
Herschel was born in the Electorate of Hanover in Germany, then part of the Holy Roman Empire, one of ten children of Isaac Herschel by his marriage to Anna Ilse Moritzen, of German Lutheran ancestry. It has been proposed by Hershel's biographer Holden that his father's family traced its roots back to Jews from Moravia who converted to Christianity in the seventeenth century, and they themselves were Lutheran Christians.
Herschel's father was an oboist in the Hanover Military Band. In 1755 the Hanoverian Guards regiment, in whose band Wilhelm and his brother Jakob were engaged as oboists, was ordered to England. At the time the crowns of Great Britain and Hanover were united under King George II. As the threat of war with France loomed, the Hanoverian Guards were recalled from England to defend Hanover. After they were defeated at the Battle of Hastenbeck, Herschel's father Isaak sent his two sons to seek refuge in England in late 1757. Although his older brother Jakob had received his dismissal from the Hanoverian Guards, Wilhelm was accused of desertion (for which he was pardoned by George III in 1782).
Wilhelm, nineteen years old at this time, was a quick student of the English language. In England he went by the English rendition of his name, Frederick William Herschel. In addition to the oboe, he played the violin and harpsichord and later the organ. He composed numerous musical works, including 24 symphonies and many concertos, as well as some church music. Six of his symphonies were recorded in April 2002 by the London Mozart Players, conducted by Matthias Bamert (Chandos 10048).
Herschel moved to Sunderland in 1761 when Charles Avison immediately engaged him as first violin and soloist for his Newcastle orchestra, where he played for one season. In "Sunderland in the County of Durh: apprill [sic] 20th 1761" he wrote his Symphony No. 8 in C Minor. He was head of the Durham Militia band 1760–61 and visited the home of Sir Ralph Milbanke at Halnaby Hall near Darlington in 1760, where he wrote two symphonies, as well as giving performances himself. After Newcastle, he moved to Leeds and Halifax where he was the first organist at St John the Baptist church (now Halifax Minster).:411
In 1766, Herschel became organist of the Octagon Chapel, Bath, a fashionable chapel in a well-known spa, in which city he was also Director of Public Concerts. He was appointed as the organist in 1766 and gave his introductory concert on 1 January 1767. As the organ was still incomplete, he showed off his versatility by performing his own compositions including a violin concerto, an oboe concerto and a harpsichord sonata. The organ was completed in October 1767.
His sister Caroline came to England in 1772 and lived with him there in New King Street, Bath. The house they shared is now the location of the Herschel Museum of Astronomy. His brothers Dietrich, Alexander and Jakob (1734–1792) also appeared as musicians of Bath. In 1780, Herschel was appointed director of the Bath orchestra, with his sister often appearing as soprano soloist.
Herschel's music led him to make the acquaintance of an amateur violinist, the Rev. John Michell of Thornhill, a former leading Cambridge mathematics professor who was already noted as England's leading geologist and was developing groundbreaking views on astronomy and the construction of telescopes. Michell sparked Herschel's interest in mathematics and lenses. Michell was later (1783) to publish work on "dark stars" (black holes). After Michell's death in 1793, Herschel bought a ten foot long, 30-inch reflecting telescope from Michell's estate which he had to reconstruct due to damage in transport.
His interest in astronomy grew stronger after he made the acquaintance of the English Astronomer Royal Nevil Maskelyne. He started building his own reflecting telescopes and would spend up to 16 hours a day grinding and polishing the speculum metal primary mirrors. He "began to look at the planets and the stars" in May 1773 and on 1 March 1774 began an astronomical journal by noting his observations of Saturn's rings and the Great Orion Nebula (M 42).
Herschel's early observational work soon focused on the search for pairs of stars that were very close together visually. Astronomers of the era expected that changes over time in the apparent separation and relative location of these stars would provide evidence for both the proper motion of stars and, by means of parallax shifts in their separation, for the distance of stars from the Earth. The latter was a method first suggested by Galileo Galilei. From the back garden of his house in New King Street, Bath, and using a 6.2-inch aperture (160 mm), 7-foot focal length (2.1 m) (f/13) Newtonian telescope "with a most capital speculum" of his own manufacture, in October 1779, Herschel began a systematic search for such stars among "every star in the Heavens", with new discoveries listed through 1792. He soon discovered many more binary and multiple stars than expected, and compiled them with careful measurements of their relative positions in two catalogues presented to the Royal Society in London in 1782 (269 double or multiple systems) and 1784 (434 systems). A third catalogue of discoveries made after 1783 was published in 1821 (145 systems).
In 1797, Herschel measured many of the systems again, and discovered changes in their relative positions that could not be attributed to the parallax caused by the Earth's orbit. He waited until 1802 (in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars; with Remarks on the Construction of the Heavens) to announce the hypothesis that the two stars might be "binary sidereal systems" orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars; with an Investigation of the Cause to which they are owing. In all, Herschel discovered over 800 confirmed double or multiple star systems, almost all of them physical rather than optical pairs. His theoretical and observational work provided the foundation for modern binary star astronomy; new catalogues adding to his work were not published until after 1820 by Friedrich Wilhelm Struve, James South and John Herschel.
In March 1781, during his search for double stars, Herschel noticed an object appearing as a disk. Herschel originally thought it was a comet or a stellar disc, which he believed he might actually resolve. He made many more observations of it, and afterwards Russian Academician Anders Lexell computed the orbit and found it to be probably planetary. Herschel agreed, determining that it must be a planet beyond the orbit of Saturn. He called the new planet the "Georgian star" (Georgium sidus) after King George III, which also brought him favour; the name did not stick. In France, where reference to the British king was to be avoided if possible, the planet was known as "Herschel" until the name "Uranus" was universally adopted. The same year, Herschel was awarded the Copley Medal and elected a Fellow of the Royal Society. In 1782, he was appointed "The King's Astronomer" (not to be confused with the Astronomer Royal). He and his sister subsequently moved to Datchet (then in Buckinghamshire but now in Berkshire) on 1 August 1782. He continued his work as a telescope maker and achieved an international reputation for their manufacture, profitably selling over 60 completed reflectors to British and Continental astronomers.
Deep sky surveysEdit
From 1782 to 1802, and most intensively from 1783 to 1790, Herschel conducted systematic surveys in search of "deep sky" or nonstellar objects with two 20-foot focal length (610 cm), 12-inch aperture (30 cm) and 18.7-inch aperture (47 cm) telescopes (in combination with his favoured 6-inch aperture instrument). Excluding duplicated and "lost" entries, Herschel ultimately discovered over 2400 objects defined by him as nebulae. (At that time, nebula was the generic term for any visually diffuse astronomical object, including galaxies beyond the Milky Way, until galaxies were confirmed as extragalactic systems by Edwin Hubble in 1924.)
Herschel published his discoveries as three catalogues: Catalogue of One Thousand New Nebulae and Clusters of Stars (1786), Catalogue of a Second Thousand New Nebulae and Clusters of Stars (1789) and the previously cited Catalogue of 500 New Nebulae ... (1802). He arranged his discoveries under eight "classes": (I) bright nebulae, (II) faint nebulae, (III) very faint nebulae, (IV) planetary nebulae, (V) very large nebulae, (VI) very compressed and rich clusters of stars, (VII) compressed clusters of small and large [faint and bright] stars, and (VIII) coarsely scattered clusters of stars. Herschel's discoveries were supplemented by those of Caroline Herschel (11 objects) and his son John Herschel (1754 objects) and published by him as General Catalogue of Nebulae and Clusters in 1864. This catalogue was later edited by John Dreyer, supplemented with discoveries by many other 19th century astronomers, and published in 1888 as the New General Catalogue (abbreviated NGC) of 7840 deep sky objects. The NGC numbering is still the most commonly used identifying label for these celestial landmarks.
Works with his sister CarolineEdit
Caroline spent many hours polishing the mirrors of high performance telescopes so that the amount of light captured was maximized. She also copied astronomical catalogues and other publications for William. After William accepted the office of King's Astronomer to George III, Caroline became his constant assistant.
In October 1783, a new 20-foot telescope came into service for William. During this time, William was attempting to observe and then record all of the observations. He had to run inside and let his eyes readjust to the artificial light before he could record anything, and then he would have to wait until his eyes were adjusted to the dark before he could observe again. Caroline became his recorder by sitting at a desk near an open window. William would shout out his observations and she would write them down along with any information he needed from a reference book.
In 1783, he gave Caroline a telescope, and she began to make astronomical discoveries in her own right, particularly comets. Between 1783 and 1787, she made an independent discovery of M110 (NGC 205), which is the second companion of the Andromeda Galaxy. During the years 1786–1797, she discovered or observed eight comets, eleven nebulae and, at her brother's suggestion, updated and corrected Flamsteed's work detailing the position of stars. Her eight comets were published between 28 August 1782 to 5 February 1787. Five of her comets were published in Philosophical Transactions of the Royal Society. William was even summoned to Windsor Castle to demonstrate Caroline's comet to the royal family. William recorded this phenomenon himself, terming it "My Sister's Comet." She wrote letters to the Astronomer Royal to announce the discovery of her second comet, and wrote to Joseph Banks upon the discovery of her third and fourth comets. Flamsteed's work was published as the British Catalogue of Stars. The catalogue contained an index of more than 560 stars that had not been previously included. She also rediscovered Comet Encke in 1795. She was honoured by the Royal Astronomical Society for this work in 1828. Caroline also continued to serve as his assistant, often taking notes while he observed at the telescope.
For her work as William's assistant, she was granted an annual salary of £50 by George III. Her appointment made her the first female in England to be honored with a government position. It also made her the first woman to be given a salary as an astronomer.
In June 1785, owing to damp conditions, he and Caroline moved to Clay Hall in Old Windsor. In 1786, the Herschels moved to a new residence on Windsor Road in Slough. He lived the rest of his life in this residence, which came to be known as Observatory House. It is no longer standing.
On 8 May 1788, he married the widow Mary Pitt (née Baldwin) at St Laurence's Church, Upton in Slough. The marriage caused a lot of tension in the brother-sister relationship. Caroline has been referred to as a bitter, jealous woman who worshipped her brother and resented her sister-in-law for invading her domestic life. With the arrival of Mary, Caroline lost her managerial and social responsibilities in the household, and with them much of her status. Caroline destroyed her journals between the years 1788 to 1798, so her feelings during this period are not entirely known. According to her memoir, Caroline then moved to separate lodgings, but continued to work as her brother's assistant. When her brother and his family were away from their home, she would often return to take care of it for them. In later life, Caroline and Lady Herschel exchanged affectionate letters.
Caroline continued to work on her astronomical work, even after William's death in 1822. She worked to verify and confirm his findings as well as putting together catalogues of nebulae. Towards the end of her life, she arranged two-and-a-half thousand nebulae and star clusters into zones of similar polar distances. She did this so that her nephew, John, could re-examine them systematically. Eventually, this list was enlarged and renamed the New General Catalogue. In 1828, she was awarded the Royal Astronomical Society's Gold Medal for her work.
The most common type of telescope at that time was the refracting telescope, which involved the refraction of light through a tube using a convex glass lens. This design was subject to chromatic aberration, a distortion of an image due to the failure of light of different component wavelengths to converge. Optician John Dollond (1706-1761) corrected for this distortion by adding flint glass to his telescope lenses. Refracting telescopes had another problem as well: an increase in magnification required an exponentially larger increase in lens radius. 
Reflector telescopes, invented by Isaac Newton in 1668, used a single concave mirror rather than a convex lens. The concave mirror gathered more light than a lens, reflecting it onto a flat mirror at the end of the telescope for viewing. A smaller mirror could provide greater magnification and a larger field of view than a convex lens. Newton's first mirror was 1.3 inches in diameter; such mirrors were rarely more than 3 inches in diameter.
Because of the poor reflectivity of mirrors made of speculum metal, Herschel eliminated the small diagonal mirror of a standard newtonian reflector from his design and tilted his primary mirror so he could view the formed image directly. This design has come to be called the Herschelian telescope.:7
The creation of larger, symmetrical mirrors was extremely difficult. Any flaw would result in a blurred image. Because no one else was making mirrors of the size and magnification desired by Herschel, he determined to make his own. This was no small undertaking. He was assisted by his sister Caroline and other family members. Caroline Herschel described the pouring of a 30-ft mirror:
"A day was set apart for casting, and the metal was in the furnace, but unfortunately it began to leak at the moment when ready for pouring, and both my brothers and the caster with his men were obliged to run out at opposite doors, for the stone flooring (which ought to have been taken up) flew about in all directions, as high as the ceiling. My poor brother fell, exhausted with heat and exertion, on a heap of brickbats. Before the second casting was attempted, everything which could ensure success had been attended to, and a very perfect metal was found in the mould, which had cracked in the cooling." Caroline Herschel
Herschel is reported to have cast, ground, and polished more than four hundred mirrors for telescopes, varying in size from from 6 to 48 inches in diameter. Not all were for his use: commissions for the making and selling of mirrors and telescopes provided him with an additional source of income. The King of Spain reportedly paid £3150 for a telescope.
An essential part of constructing and maintaining telescopes was the grinding and polishing of their mirrors. This had to be done repeatedly, whenever the mirrors deformed or tarnished during use.
The 40ft telescopeEdit
The largest and most famous of Herschel's telescopes was a reflecting telescope with a 49 1⁄2-inch-diameter (1.26 m) primary mirror and a 40-foot (12 m) focal length. The 40-foot was, at that time, the largest scientific instrument that had been built. It was hailed as a triumph of "human perseverance and zeal for the sublimest science".:215
The 40-foot telescope proved very cumbersome, and not very effective at showing clearer images. Most of Herschel's observations were done with a smaller 18.5-inch (47 cm) 20-foot-focal-length (6.1 m) reflector.
Herschel discovered that unfilled telescope apertures can be used to obtain high angular resolution, something which became the essential basis for interferometric imaging in astronomy (in particular aperture masking interferometry and hypertelescopes).
Reconstruction of the 20ft telescopeEdit
In 2012, the BBC Stargazing Live television programme built a replica of the 20-foot telescope using Herschel's original plans but modern materials. It is to be considered a close modern approximation rather than an exact replica. A modern glass mirror was used, the frame uses metal scaffolding and the tube is a sewer pipe. The telescope was shown on the programme in January 2013 and stands on the Art, Design and Technology campus of the University of Derby where it will be used for educational purposes.
Life on other celestial bodiesEdit
Herschel was sure that he had found ample evidence of life on the Moon and compared it to the English countryside. He did not refrain himself from theorising that the other planets were populated, with a special interest in Mars, which was in line with most of his contemporary scientists. At Herschel's time, scientists tended to believe in a plurality of civilised worlds; in contrast, most religious thinkers referred to unique properties of the earth. Herschel went so far to speculate that the interior of the sun was populated.
Sunspots, climate, and wheat yieldsEdit
Herschel started to examine the correlation of solar variation and solar cycle and climate. Over a period of 40 years (1779–1818), Herschel had regularly observed sunspots and their variations in number, form and size. Most of his observations took place in a period of low solar activity, the Dalton minimum, when sunspots were relatively few in number. This was one of the reasons why Herschel was not able to identify the standard 11-year period in solar activity. Herschel compared his observations with the series of wheat prices published by Adam Smith in The Wealth of Nations.
In 1801, Herschel reported his findings to the Royal Society and indicated five prolonged periods of few sunspots correlated with the price of wheat. Herschel's study was ridiculed by some of his contemporaries but did initiate further attempts to find a correlation. Later in the 19th century, William Stanley Jevons proposed the 11-year cycle with Herschel's basic idea of a correlation between the low number of sunspots and lower yields explaining recurring booms and slumps in the economy. Herschel's speculation on a connection between sunspots and regional climate, using the market price of wheat as a proxy, continues to be cited.
According to one study, the influence of solar activity can actually be seen on the historical wheat market in England over ten solar cycles between 1600 and 1700. The evaluation is controversial and the significance of the correlation is doubted by some scientists.
|Uranus||13 March 1781|
|Oberon||11 January 1787|
|Titania||11 January 1787|
|Enceladus||28 August 1789|
|Mimas||17 September 1789|
In his later career, Herschel discovered two moons of Saturn, Mimas and Enceladus; as well as two moons of Uranus, Titania and Oberon. He did not give these moons their names; they were named by his son John in 1847 and 1852, respectively, after his death. Herschel measured the axial tilt of Mars and discovered that the martian ice caps, first observed by Giovanni Domenico Cassini (1666) and Christiaan Huygens (1672), changed size with that planet's seasons. It has been suggested that Herschel might have discovered rings around Uranus.
Herschel introduced but did not create the word "asteroid", meaning star-like (from the Greek asteroeides, aster "star" + -eidos "form, shape"), in 1802 (shortly after Olbers discovered the second minor planet, 2 Pallas, in late March), to describe the star-like appearance of the small moons of the giant planets and of the minor planets; the planets all show discs, by comparison. By the 1850s 'asteroid' became a standard term for describing certain minor planets.
From studying the proper motion of stars, the nature and extent of the solar motion was first demonstrated by Herschel in 1783, along with first determining the direction for the solar apex to Lambda Herculis, only 10° away from today's accepted position.
He also studied the structure of the Milky Way and concluded that it was in the shape of a disk. He incorrectly assumed the sun was in the centre of the disc, a theory known as Galactocentrism, which was eventually corrected by the findings of Harlow Shapley in 1918.
Discovery of infrared radiation in sunlightEdit
On 11 February 1800, Herschel was testing filters for the sun so he could observe sun spots. 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.
Family and deathEdit
William Herschel and Mary had one child, John, born at Observatory House on 7 March 1792. William's personal background and rise as man of science had a profound impact on the upbringing of his son and grandchildren. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1788. In 1816, William was made a Knight of the Royal Guelphic Order by the Prince Regent and was accorded the honorary title 'Sir' although this was not the equivalent of an official British knighthood. He helped to found the Astronomical Society of London in 1820, which in 1831 received a royal charter and became the Royal Astronomical Society. In 1813, he was elected a foreign member of the Royal Swedish Academy of Sciences.
On 25 August 1822, Herschel died at Observatory House, Windsor Road, Slough, after a long illness. He was buried at nearby St Laurence's Church, Upton, Slough. Herschel's epitaph is
|“||Coelorum perrupit claustra
(He broke through the barriers of the heavens) 
Caroline was deeply distressed by his death, and soon after his burial she returned to Hanover, a decision she later regretted. She had lived in England for fifty years. Her interests were much more in line with her nephew John Herschel, also an astronomer, than with her surviving family in Hanover. She continued to work on the organization and cataloguing of nebulae, creating what would later become the basis of the New General Catalogue. She died on 9 January 1848.
Herschel is quite respected in Slough and there are several memorials to him and his discoveries. In 2011 a new bus station, the design of which was inspired by the infrared experiment of William Herschel, was built in the centre of Slough.
Herschel's complete musical works were as follows:
- 18 symphonies for small orchestra (1760–1762)
- 6 symphonies for large orchestra (1762–1764)
- 12 concertos for oboe, violin and viola (1759–1764)
- 2 concertos for organ
- 6 sonatas for violin, cello and harpsichord (published 1769)
- 12 solos for violin and basso continuo (1763)
- 24 capriccios and 1 sonata for solo violin
- 1 andante for two basset horns, two oboes, two horns and two bassoons.
Keyboard works for organ and harpsichord:
Named after HerschelEdit
- The astrological symbol for planet Uranus ( ) features the capital initial letter of Herschel's surname.
- Mu Cephei is also known as Herschel's Garnet Star
- Herschel, a crater on the Moon
- Herschel, a large impact basin on Mars
- The enormous crater Herschel on Saturn's moon Mimas
- The Herschel gap in Saturn's rings.
- 2000 Herschel, an asteroid
- The William Herschel Telescope on La Palma
- The Herschel Space Observatory, successfully launched by the European Space Agency on 14 May 2009. It is the largest space telescope of its kind
- Herschel Grammar School, Slough
- Rue Herschel, a street in the 6th Arrondissement of Paris.
- The Herschel Building at Bath College, Bath
- The Herschel building at Newcastle University, Newcastle, United Kingdom
- Herschel Museum of Astronomy, at 19 New King Street in Bath.
- Herschelschule, Hanover, Germany, a grammar school
- Herschel, Saskatchewan, Canada is a small, rural village that is home to the Ancient Echoes Interpretative Centre
- The Herschel Observatory, at the Universitas School in Santos, Brazil.
- The lunar crater C. Herschel, the asteroid 281 Lucretia, and the comet 35P/Herschel-Rigollet are named after his sister Caroline Herschel.
- The public house "Herschel Arms" at 22 Park Street, Slough is named after him and is quite close to the site of Observatory House.
- Herschel Astronomical Society, the operator of the Herschel Memorial Observatory based in Eton, Berkshire.
- Herschel Park, Slough.
- The shape of Slough Bus Station, built in 2011, was inspired by Herschel's infrared experiment.
- Hoskin, Michael, ed. (2003). Caroline Herschel's autobiographies. Cambridge: Science History Publ. p. 13. ISBN 0905193067.
- "Herschel". Random House Webster's Unabridged Dictionary.
- "HERSCHEL, SIR WILLIAM - JewishEncyclopedia.com". www.jewishencyclopedia.com.
- Barentine, John C. (2015). The Lost Constellations: A History of Obsolete, Extinct, or Forgotten Star Lore. Springer. p. 410.
- Lubbock, Constance Ann (1933). The Herschel Chronicle: The Life-story of William Herschel and His Sister, Caroline Herschel. CUP Archive. pp. 1–.
- Hoskin, M. (2004). "Was William Herschel a deserter?". Journal for the History of Astronomy. 35, Part 3 (120): 356–358. Bibcode:2004JHA....35..356H.
- Clerke, Agnes M (1908). "A Popular History of Astronomy During the Nineteenth Century" (4 (republished as eBook number 28247) ed.). London (republished eText): Adam and Charles Black (republished Project Gutenberg): 18.
- Holmes 2008, pp. 67.
- Levy, David H. (1994). The Quest for Comets An Explosive Trail of Beauty and Danger. Boston, MA: Springer US. p. 38. ISBN 148995998X. Retrieved 17 May 2018.
- Aitken, Robert Grant (1935). The Binary Stars. New York and London: McGraw-Hill Book Company, Inc. pp. 4–9. ISBN 978-1117504094.
- Mullaney 2007, p. 10
- William Herschel's Double Star Catalog. Handprint.com (5 January 2011). Retrieved on 5 June 2011.
- "Discovering New Planets". Archived from the original on 9 April 2010. Retrieved 11 September 2013. . National Air and Space Museum.
- Holmes 2008, pp. 96.
- Kuhn, Thomas S. (1970). The structure of scientific revolutions. Chicago: The University of Chicago Press. p. 115. ISBN 0226458040.
- Astronomical League National – Herschel Club – Friedrich Wilhelm Herschel. Astroleague.org. Retrieved on 5 June 2011.
- Mullaney 2007, p. 14
- esa. "Caroline and William Herschel: Revealing the invisible". European Space Agency. Retrieved 2016-04-24.
- Herschel, Caroline (1876). Herschel, Mrs. John, ed. Memoir and Correspondence of Caroline Herschel. London: John Murray, Albermarle Street.
- Roberts, Jacob (2017). "A Giant of Astronomy". Distillations. 3 (3): 6-11. Retrieved May 16, 2018.
- Fernie, J. Donald (November–December 2007). The Inimitable Caroline. American Scientist. pp. 486–488.
- Hoskin, Michael (2011). Discoverers of the Universe: William and Caroline Herschel. Princeton University Press. ISBN 9780691148335.
- Holmes 2008, pp. 410.
- Baldwin, Emily. "Caroline Herschel (1750–1848)". www.sheisanastronomer.org. Retrieved 2016-04-24.
- Ogilvie, Marilyn Bailey (1986). Women in Science: Antiquity Through the Nineteenth Century. MIT Press. pp. 97–98. ISBN 0-262-65038-X.
- Zielinski, Sarah. "Caroline Herschel: Assistant or Astronomer?". smithsonianmag.com. Smithsonian Institution. Retrieved 1 April 2018.
- Holmes 2008, pp. 186.
- Bratton, Mark (2011). The complete guide to the Herschel objects : Sir William Herschel's star clusters, nebulae, and galaxies. Cambridge: Cambridge University Press. p. 7. ISBN 9780521768924. Retrieved 17 May 2018.
- Hastings, C. S. (1891). "History of the telescope". The Sidereal Messenger: A Monthly Review of Astronomy. 10: 342. Retrieved 17 May 2018.
- Holmes 2008, pp. 190.
- BBC builds William Herschel's telescope for Stargazing Live Ariel at BBC Learning, 10 January 2013
- Basalla, George (2006). Civilized life in the universe : scientists on intelligent extraterrestrials. New York: Oxford University Press. p. 52. ISBN 9780195171815.
- Herschel, W. (1801). "Observations tending to investigate the nature of the Sun, in order to find the causes or symptoms of its variable emission of light and heat; With remarks on the use that may possibly be drawn from solar observations". Philosophical Transactions of the Royal Society of London. 91: 265–318. Bibcode:1801RSPT...91..265H. doi:10.1098/rstl.1801.0015. JSTOR 107097.
- Ball, Philip (22 December 2003). "Sun set food prices in the Middle Ages". Nature. doi:10.1038/news031215-12. Retrieved 17 May 2018.
- Pustil’nik, Lev A.; Din, Gregory Yom (September 2004). "Influence of solar activity on the state of the wheat market in medieval England". Solar Physics. 223 (1-2): 335–356. doi:10.1007/s11207-004-5356-5. Retrieved 17 May 2018.
- Nye, Mary Jo (2003). The Cambridge History of Science: Volume 5, The Modern Physical and Mathematical Sciences. 5. Cambridge: Cambridge University Press. p. 508. ISBN 978-0521571999.
- Lockwood, Mike. "Solar Influence on Global and Regional Climates". Surveys in Geophysics. 33: 503–534. Bibcode:2012SGeo...33..503L. doi:10.1007/s10712-012-9181-3.
- Love, J. J. (2013). "On the insignificance of Herschel's sunspot correlation" (PDF). Geophysical Research Letters. 40: 4171–4176. Bibcode:2013GeoRL..40.4171L. doi:10.1002/grl.50846.
- Rincon, Paul (18 April 2007). "Uranus rings 'were seen in 1700s'". BBC News.
- In an oral presentation ("HAD Meeting with DPS, Denver, October 2013 – Abstracts of Papers". Archived from the original on 1 September 2014. Retrieved 14 October 2013.), Clifford Cunningham presented his finding that the word has been coined by Charles Burney, Jr., the son of a friend of Herschel, see "Local expert reveals who really coined the word 'asteroid'". South Florida Sun-Sentinel. 8 October 2013. Retrieved 10 October 2013.. See also Wall, Mike (10 January 2011). "Who Really Invented the Word 'Asteroid' for Space Rocks?". SPACE.com. Retrieved 10 October 2013.
- Lankford, John (1997). History of astronomy: an encyclopedia. Garland encyclopedias in the history of science. 1. Taylor & Francis. p. 258. ISBN 0-8153-0322-X.
- Herschel, William (1783). "On the Proper Motion of the Sun and Solar System; With an Account of Several Changes That Have Happened among the Fixed Stars since the Time of Mr. Flamstead". Philosophical Transactions of the Royal Society of London. 73: 247–83. doi:10.1098/rstl.1783.0017. JSTOR 106492.
- Hoskin, M. (1980), "Herschel's Determination of the Solar Apex", Journal for the History of Astronomy, 11: 153–163, Bibcode:1980JHA....11..153H, doi:10.1177/002182868001100301.
- Rowan-Robinson, Michael (2013). Night Vision: Exploring the Infrared Universe. Cambridge University Press. p. 23. ISBN 9781107024762. OCLC 780161457.
- Aughton, Peter (2011). The story of astronomy. New York: Quercus. ISBN 1623653037. Retrieved 17 May 2018.
- Azzouni, Jody (July 20, 2017). Ontology Without Borders. Oxford University Press. ISBN 9780190622558. Retrieved 17 May 2018.
- "Book of Members, 1780–2010: Chapter H" (PDF). American Academy of Arts and Sciences. Retrieved 28 July 2014.
- Hanham, A. & Hoskin,, M. (2013). "The Herschel Knighthoods: Facts and Fiction". Journal for the History of Astronomy. 44 (120): 149–164. Bibcode:2013JHA....44..149H.
- Pendergrast, Mark (2004). Mirror mirror : a history of the human love affair with reflection. New York: Basic Books. p. 159. ISBN 978-0465054718. Retrieved 17 May 2018.
- Olson, Roberta J. M.; Pasachoff, Jay M. (2012). "The Comets of Caroline Herschel (1750-1848), Sleuth of the Skies at Slough" (PDF). Culture and Cosmos. Retrieved 24 April 2016.
- "Caroline Herschel Biography". Space.com. Retrieved 23 April 2016.
- Serck, Linda (28 May 2011). "Slough bus station: Silver dolphin or beached whale?". bbc.co.uk. Retrieved 13 August 2012.
- "WILLIAM HERSCHEL (1738–1822): Organ works". asterope.bajaobs.hu. Archived from the original on 25 June 2013. Retrieved 1 May 2013.
- Holden, Edward S. (1881). Sir William Herschel, his life and works. New York: Charles Scribner's Sons. Wikisource.
- Holmes, Richard (2008). The age of wonder. New York: Vintage Books. ISBN 978-1-4000-3187-0.
- Mullaney, James (2007). The Herschel objects and how to observe them. ISBN 978-0-387-68124-5. Retrieved 5 June 2011.
- "William Herschel" by Michael Hoskin. New Dictionary of Scientific Biography Scribners, 2008. v. 3, pp. 289–291.
- Biography: JRASC 74 (1980) 134
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- Works written by or about William Herschel at Wikisource
- Articles and letters published in the Philosophical Transactions and available online (70 items, June 2016)
- William Herschel's Deep Sky Catalog
- The William Herschel Double Star Catalogs Restored
- Full text of Herschel by Hector Macpherson.
- Full text of The Story of the Herschels (1886) from Project Gutenberg
- Portraits of William Herschel at the National Portrait Gallery (United Kingdom)
- Herschel Museum of Astronomy located in his Bath home
- William Herschel Society
- The Oboe Concertos of Sir William Herschel, Wilbert Davis Jerome ed. ISBN 0-87169-225-2
- Works by or about William Herschel in libraries (WorldCat catalog)
- A notebook of Herschel's, dated from 1759 is available in the digital collections of the Linda Hall Library.
- Portraits of William Herschel (and other members of the family) from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections
- Michael Lemonick: William Herschel, the First Observational Cosmologist, 12 Nov 2008, Fermilab Colloquium, Text
- Free scores by William Herschel at the International Music Score Library Project (IMSLP)