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Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
and
composer A composer is a person who writes music. The term is especially used to indicate composers of Western classical music, or those who are composers by occupation. Many composers are, or were, also skilled performers of music. Etymology and Defi ...
. He frequently collaborated with his younger sister and fellow astronomer
Caroline Herschel Caroline Lucretia Herschel (; 16 March 1750 – 9 January 1848) was a German born British astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigolle ...
(1750–1848). Born in the
Electorate of Hanover The Electorate of Hanover (german: Kurfürstentum Hannover or simply ''Kurhannover'') was an electorate of the Holy Roman Empire, located in northwestern Germany and taking its name from the capital city of Hanover. It was formally known as ...
, William Herschel followed his father into the military band of Hanover, before emigrating to
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...
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
nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...
e 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 The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only in ...
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 Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
. This was the first planet to be discovered since antiquity, and Herschel became famous overnight. As a result of this discovery,
George III George III (George William Frederick; 4 June 173829 January 1820) was King of Great Britain and of Ireland from 25 October 1760 until the union of the two kingdoms on 1 January 1801, after which he was King of the United Kingdom of Great Br ...
appointed him Court Astronomer. He was elected a
Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the judges of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural science, natural knowledge, incl ...
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 the course of these investigations, Herschel discovered
infrared radiation Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
. Other work included an improved determination of the rotation period of
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
, the discovery that the Martian polar caps vary seasonally, the discovery of Titania and
Oberon Oberon () is a king of the fairies in medieval and Renaissance literature. He is best known as a character in William Shakespeare's play ''A Midsummer Night's Dream'', in which he is King of the Fairies and spouse of Titania, Queen of the Fairi ...
(moons of Uranus) and
Enceladus Enceladus is the sixth-largest moon of Saturn (19th largest in the Solar System). It is about in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most refle ...
and Mimas (moons of
Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
). Herschel was made a Knight of the
Royal Guelphic Order The Royal Guelphic Order (german: Königliche Guelphen-Orden), sometimes referred to as the Hanoverian Guelphic Order, is a Hanoverian order of chivalry instituted on 28 April 1815 by the Prince Regent (later King George IV). It takes its name ...
in 1816. He was the first
President of the Royal Astronomical Society The President of the Royal Astronomical Society (prior to 1831 known as President of the Astronomical Society of London) chairs the Council of the Royal Astronomical Society (RAS) and its formal meetings. They also liaise with government organisati ...
when it was founded in 1820. He died in August 1822, and his work was continued by his only son,
John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...
.


Early life and musical activities

Herschel was born in the
Electorate of Hanover The Electorate of Hanover (german: Kurfürstentum Hannover or simply ''Kurhannover'') was an electorate of the Holy Roman Empire, located in northwestern Germany and taking its name from the capital city of Hanover. It was formally known as ...
in Germany, then part of the
Holy Roman Empire The Holy Roman Empire was a Polity, political entity in Western Europe, Western, Central Europe, Central, and Southern Europe that developed during the Early Middle Ages and continued until its Dissolution of the Holy Roman Empire, dissolution i ...
, one of ten children of Issak Herschel and his wife, Anna Ilse Moritzen, of German Lutheran ancestry. His forefathers came from
Pirna Pirna (; hsb, Pěrno; ) is a town in Saxony, Germany and capital of the administrative district Sächsische Schweiz-Osterzgebirge. The town's population is over 37,000. Pirna is located near Dresden and is an important district town as well as ...
, in Saxony. Theories that they were Protestants from Bohemia have been questioned by Hamel as the surname Herschel already occurs a century earlier in the very same area that the family lived in. Herschel's father was an
oboist An oboist (formerly hautboist) is a musician who plays the oboe or any oboe family instrument, including the oboe d'amore, cor anglais or English horn, bass oboe and piccolo oboe or oboe musette. The following is a list of notable past and pres ...
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 Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...
and
Hanover Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German state of Lower Saxony. Its 535,932 (2021) inhabitants make it the 13th-largest city in Germany as well as the fourth-largest city in Northern Germany ...
were
united United may refer to: Places * United, Pennsylvania, an unincorporated community * United, West Virginia, an unincorporated community Arts and entertainment Films * ''United'' (2003 film), a Norwegian film * ''United'' (2011 film), a BBC Two f ...
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 The Battle of Hastenbeck (26 July 1757) was fought as part of the Invasion of Hanover during the Seven Years' War between the allied forces of Hanover, Hesse-Kassel (or Hesse-Cassel) and Brunswick, and the French. The allies were defeated by ...
, 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 George III (George William Frederick; 4 June 173829 January 1820) was King of Great Britain and of Ireland from 25 October 1760 until the union of the two kingdoms on 1 January 1801, after which he was King of the United Kingdom of Great Br ...
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 A harpsichord ( it, clavicembalo; french: clavecin; german: Cembalo; es, clavecín; pt, cravo; nl, klavecimbel; pl, klawesyn) is a musical instrument played by means of a keyboard. This activates a row of levers that turn a trigger mechanism ...
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 London Mozart Players (LMP) are a British chamber orchestra founded in 1949. LMP are the longest-established chamber orchestra in the United Kingdom. Since 1989, the orchestra has been Resident Orchestra at Fairfield Halls, Croydon. History B ...
, conducted by
Matthias Bamert Matthias Bamert (born July 5, 1942 in Ersigen, Canton of Bern) is a Swiss composer and conductor. In addition to studies in Switzerland, Bamert studied music in Darmstadt and in Paris, with Pierre Boulez and Karlheinz Stockhausen, and their influ ...
(Chandos 10048). Herschel moved to Sunderland in 1761 when
Charles Avison Charles Avison (; 16 February 1709 (baptised)9 or 10 May 1770) was an English composer during the Baroque and Classical periods. He was a church organist at St John The Baptist Church in Newcastle and at St. Nicholas's Church (later Newcas ...
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 20th 1761" he wrote his ''Symphony No. 8 in C Minor.'' He was head of the Durham Militia band from 1760 to 1761. He visited the home of Sir Ralph Milbanke at Halnaby Hall near
Darlington Darlington is a market town in the Borough of Darlington, County Durham, England. The River Skerne flows through the town; it is a tributary of the River Tees. The Tees itself flows south of the town. In the 19th century, Darlington underwen ...
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 Halifax Minster is the minster church of Halifax, Calderdale, West Yorkshire, England. The church is dedicated to St John the Baptist. Formerly the parish church of the town, it was granted minster status in 2009. Halifax Minster is one of t ...
). In 1766, Herschel became organist of the
Octagon Chapel, Bath The Octagon Chapel in Milsom Street, Bath, Somerset, England was built in 1767 and has been designated as a Grade II* listed building. History The building was designed as a church by the architect Timothy Lightholder (or Lightoler), whose spe ...
, 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 A violin concerto is a concerto for solo violin (occasionally, two or more violins) and instrumental ensemble (customarily orchestra). Such works have been written since the Baroque period, when the solo concerto form was first developed, up thro ...
, an
oboe concerto A number of concertos (as well as non-concerto works) have been written for the oboe, both as a solo instrument as well as in conjunction with other solo instrument(s), and accompanied by string orchestra, chamber orchestra, full orchestra, conce ...
and a
harpsichord A harpsichord ( it, clavicembalo; french: clavecin; german: Cembalo; es, clavecín; pt, cravo; nl, klavecimbel; pl, klawesyn) is a musical instrument played by means of a keyboard. This activates a row of levers that turn a trigger mechanism ...
sonata. On 4 October 1767, he performed on the organ for the official opening of the Octagon Chapel. His sister Caroline arrived in England on 24 August 1772 to live with William in New King Street, Bath. The house they shared is now the location of the Herschel Museum of Astronomy. Herschel's 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.


Astronomy

Herschel's reading in
natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...
during the 1770s indicates his personal interests but also suggests an intention to be upwardly mobile socially and professionally. He was well-positioned to engage with eighteenth-century "philosophical Gentleman" or
philomath A philomath () is a lover of learning and studying. The term is from Greek (; "beloved", "loving", as in philosophy or philanthropy) and , (, ; "to learn", as in polymath). Philomathy is similar to, but distinguished from, philosophy in that ...
s, of wide-ranging logical and practical tastes. Herschel's intellectual curiosity and interest in music eventually led him to astronomy. After reading Robert Smith's ''Harmonics, or the Philosophy of Musical Sounds'' (1749), he took up Smith's ''A Compleat System of Opticks'' (1738), which described techniques of telescope construction. He also read
James Ferguson James Ferguson may refer to: Entertainment * Jim Ferguson (born 1948), American jazz and classical guitarist * Jim Ferguson, American guitarist, past member of Lotion * Jim Ferguson, American movie critic, Board of Directors member for the Broadca ...
's ''Astronomy explained upon Sir Isaac Newton's principles and made easy to those who have not studied mathematics'' (1756) and William Emerson's ''The elements of trigonometry'' (1749), ''The elements of optics'' (1768) and ''The principles of mechanics'' (1754). Herschel took lessons from a local mirror-builder and having obtained both tools and a level of expertise, started building his own
reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...
s. He would spend up to 16 hours a day grinding and polishing the
speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming ...
primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
s. He relied on the assistance of other family members, particularly his sister Caroline and his brother Alexander, a skilled mechanical craftsperson. 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 The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae and is visible to the naked eye in the nig ...
(M42). The English
Astronomer Royal Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834. The post ...
Nevil Maskelyne Nevil Maskelyne (; 6 October 1732 – 9 February 1811) was the fifth British Astronomer Royal. He held the office from 1765 to 1811. He was the first person to scientifically measure the mass of the planet Earth. He created the ''British Nau ...
visited the Herschels while they were at Walcot (which they left on 29 September 1777). By 1779, Herschel had also made the acquaintance of Sir
William Watson William, Willie, Bill or Billy Watson may refer to: Entertainment * William Watson (songwriter) (1794–1840), English concert hall singer and songwriter * William Watson (poet) (1858–1935), English poet * Billy Watson (actor) (1923–2022), A ...
, who invited him to join the Bath Philosophical Society. Herschel became an active member, and through Watson would greatly enlarge his circle of contacts. A few years later, in 1785, Herschel was elected an international member of the
American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...
in Philadelphia.


Double stars

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 Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
of stars and, by means of
parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...
shifts in their separation, for the distance of stars from the Earth. The latter was a method first suggested by
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
. From the back garden of his house in New King Street, Bath, and using a , (f/13)
Newtonian telescope The Newtonian telescope, also called the Newtonian reflector or just a Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton, using a concave primary mirror and a flat diagonal secondary mirror. Newto ...
"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 Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that ta ...
and
multiple star A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a ''star cluster'' or ''galaxy'', although, broadly speaking, ...
s than expected, and compiled them with careful measurements of their relative positions in two catalogues presented to the
Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
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). The Rev.
John Michell John Michell (; 25 December 1724 – 21 April 1793) was an English natural philosopher and clergyman who provided pioneering insights into a wide range of scientific fields including astronomy, geology, optics, and gravitation. Considered "o ...
of Thornhill published work in 1767 on the distribution of double stars, and in 1783 on "dark stars", that may have influenced Herschel. After Michell's death in 1793, Herschel bought a ten-foot-long, 30-inch reflecting telescope from Michell's estate. 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 In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong ...
, 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 Sir James South FRS FRSE PRAS FLS LLD (October 1785 – 19 October 1867) was a British astronomer. He was a joint founder of the Astronomical Society of London, and it was under his name, as President of the Society in 1831, that a peti ...
and
John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...
.


Uranus

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 reported the sighting to
Nevil Maskelyne Nevil Maskelyne (; 6 October 1732 – 9 February 1811) was the fifth British Astronomer Royal. He held the office from 1765 to 1811. He was the first person to scientifically measure the mass of the planet Earth. He created the ''British Nau ...
the
Astronomer Royal Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834. The post ...
. 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 George III (George William Frederick; 4 June 173829 January 1820) was King of Great Britain and of Ireland from 25 October 1760 until the union of the two kingdoms on 1 January 1801, after which he was King of the United Kingdom of Great Br ...
, 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 The Copley Medal is an award given by the Royal Society, for "outstanding achievements in research in any branch of science". It alternates between the physical sciences or mathematics and the biological sciences. Given every year, the medal is t ...
and elected a Fellow of the
Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
. In 1782, he was appointed "The King's Astronomer" (not to be confused with the
Astronomer Royal Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834. The post ...
). On 1 August 1782 Herschel and his sister Caroline moved to
Datchet Datchet is a village and civil parish in the Royal Borough of Windsor and Maidenhead in Berkshire, England, located on the north bank of the River Thames. Historically part of Buckinghamshire, and the Stoke Hundred, the village was eventuall ...
(then in
Buckinghamshire Buckinghamshire (), abbreviated Bucks, is a ceremonial county in South East England that borders Greater London to the south-east, Berkshire to the south, Oxfordshire to the west, Northamptonshire to the north, Bedfordshire to the north-ea ...
but now in
Berkshire Berkshire ( ; in the 17th century sometimes spelt phonetically as Barkeshire; abbreviated Berks.) is a historic county in South East England. One of the home counties, Berkshire was recognised by Queen Elizabeth II as the Royal County of Berk ...
). There, he continued his work as an astronomer and telescope maker. He achieved an international reputation for their manufacture, profitably selling over 60 completed reflectors to British and Continental astronomers.


Deep sky surveys

From 1782 to 1802, and most intensively from 1783 to 1790, Herschel conducted systematic surveys in search of "deep-sky" or non-stellar objects with two , and telescopes (in combination with his favoured 6-inch-aperture instrument). Excluding duplicated and "lost" entries, Herschel ultimately discovered over 2,400 objects defined by him as
nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...
e. (At that time, nebula was the generic term for any visually diffuse astronomical object, including galaxies beyond the
Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...
, until galaxies were confirmed as extragalactic systems by
Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects ...
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 aint and brightstars, 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 John Dreyer may refer to: *John Louis Emil Dreyer, Danish-Irish astronomer *John Dreyer (footballer) John Brian Dreyer (born 11 June 1963) is an English former professional footballer and manager who played in defence and midfield. He is curren ...
, supplemented with discoveries by many other 19th-century astronomers, and published in 1888 as the ''
New General Catalogue The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...
'' (abbreviated NGC) of 7,840 deep-sky objects. The NGC numbering is still the most commonly used identifying label for these celestial landmarks. He discovered NGC 12, NGC 13, NGC 14, NGC 16, NGC 23, NGC 24,
NGC 7457 NGC 7457 is an unbarred lenticular galaxy in the constellation Pegasus. NGC 7457 is its New General Catalogue designation. It was discovered by the astronomer William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Hersche ...
(work in progress).


Works with his sister Caroline Herschel

Following the death of their father, William suggested that Caroline join him in Bath, England. In 1772, Caroline was first introduced to astronomy by her brother. 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. Caroline began to make astronomical discoveries in her own right, particularly
comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
s. In 1783, William built her a small Newtonian reflector telescope, with a handle to make a vertical sweep of the sky. Between 1783 and 1787, she made an independent discovery of M110 (NGC 205), which is the second companion of the
Andromeda Galaxy The Andromeda Galaxy (IPA: ), also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about approximately from Earth and the nearest large galaxy to the Milky Way. The gal ...
. During the years 1786–1797, she discovered or observed eight comets. She found fourteen new nebulae and, at her brother's suggestion, updated and corrected Flamsteed's work detailing the position of stars. She also rediscovered
Comet Encke Comet Encke , or Encke's Comet (official designation: 2P/Encke), is a periodic comet that completes an orbit of the Sun once every 3.3 years. (This is the shortest period of a reasonably bright comet; the faint main-belt comet 311P/PanSTARRS ha ...
in 1795. Caroline Herschel's 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 ''Philosophical Transactions of the Royal Society'' is a scientific journal published by the Royal Society. In its earliest days, it was a private venture of the Royal Society's secretary. It was established in 1665, making it the first journa ...
''. 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. The ''Catalogue of stars taken from Mr Flamsteed's observations'' contained an index of more than 560 stars that had not been previously included. Caroline Herschel was honoured by the
Royal Astronomical Society (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NGO ...
for this work in 1828. Caroline also continued to serve as William Herschel's 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 honoured 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, William and Caroline moved to Clay Hall in
Old Windsor Old Windsor is a large village and civil parish, in the Royal Borough of Windsor and Maidenhead, in Berkshire, England. It is bounded by the River Thames to the east and the Windsor Great Park to the west. Etymology The name originates from old ...
. On 3 April 1786, the Herschels moved to a new residence on Windsor Road in
Slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...
. Herschel lived the rest of his life in this residence, which came to be known as Observatory House. It was demolished in 1963. William Herschel's marriage in 1788 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 her astronomical work 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 The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...
''. In 1828, she was awarded the
Gold Medal of the Royal Astronomical Society The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...
for her work.


Herschel's telescopes

The most common type of telescope at that time was the
refracting telescope A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...
, which involved the refraction of light through a tube using a convex glass
lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
. This design was subject to
chromatic aberration In optics, chromatic aberration (CA), also called chromatic distortion and spherochromatism, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the w ...
, a distortion of an image due to the failure of light of different component wavelengths to converge. Optician
John Dollond John Dollond FRS (10 June O.S. (21 June N.S.) 170630 November 1761) was an English optician, known for his successful optics business and his patenting and commercialization of achromatic doublets. Biography Dollond was the son of a Hugue ...
(1706–1761) tried to correct for this distortion by combining two separate lenses, but it was still difficult to achieve good resolution for far distant light sources. Reflector telescopes, invented by
Isaac Newton Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the grea ...
in 1668, used a single concave mirror rather than a convex lens. This avoids chromatic aberration. 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 Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming ...
, Herschel eliminated the small diagonal mirror of a standard
newtonian reflector The Newtonian telescope, also called the Newtonian reflector or just a Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton, using a concave primary mirror and a flat diagonal secondary mirror. Newton' ...
from his design and tilted his primary mirror so he could view the formed image directly. This "front view" design has come to be called the Herschelian telescope. 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-foot-focal-length mirror: Herschel is reported to have cast, ground, and polished more than four hundred mirrors for telescopes, varying in size from 6 to 48 inches in diameter. Herschel and his assistants built and sold at least sixty complete telescopes of various sizes. Commissions for the making and selling of mirrors and telescopes provided Herschel with an additional source of income. The King of Spain reportedly paid £3,150 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 only way to test the accuracy of a mirror was to use it.


40-foot telescope

The largest and most famous of Herschel's telescopes was a reflecting telescope with a 49-inch-diameter (1.26 m)
primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...
and a focal length. The 40-foot telescope was, at that time, the largest
scientific instrument A scientific instrument is a device or tool used for scientific purposes, including the study of both natural phenomena and theoretical research. History Historically, the definition of a scientific instrument has varied, based on usage, laws, an ...
that had been built. It was hailed as a triumph of "human perseverance and zeal for the sublimest science". In 1785 Herschel approached King George for money to cover the cost of building the 40-foot telescope. He received £4,000. Without royal patronage, the telescope could not have been created. As it was, it took five years, and went over budget. The Herschel home in Slough became a scramble of "labourers and workmen, smiths and carpenters". A 40-foot telescope tube had to be cast of iron. The tube was large enough to walk through. Mirror blanks were poured from
Speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming ...
, a mix of
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
and
tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
. They were almost four feet (1.2 m) in diameter and weighed 1,000 pounds (454 kg). When the first disk deformed due to its weight, a second thicker one was made with a higher content of copper. The mirrors had to be hand-polished, a painstaking process. A mirror was repeatedly put into the telescope and removed again to ensure that it was properly formed. When a mirror deformed or tarnished, it had to be removed, repolished and replaced in the apparatus. A huge rotating platform was built to support the telescope, enabling it to be repositioned by assistants as a sweep progressed. A platform near the top of the tube enabled the viewer to look down into the tube and view the resulting image. In 1789, shortly after this instrument was operational, Herschel discovered a new
moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
of
Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
: Mimas, only 250 miles (400 km) in diameter. Discovery of a second moon (
Enceladus Enceladus is the sixth-largest moon of Saturn (19th largest in the Solar System). It is about in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most refle ...
) followed, within the first month of observation. The 40-foot (12.2-metre) telescope proved very cumbersome, and in spite of its size, not very effective at showing clearer images. Herschel's technological innovations had taken him to the limits of what was possible with the technology of his day. The 40-foot would not be improved upon until the Victorians developed techniques for the precision engineering of large, high-quality mirrors. William Herschel was disappointed with it. Most of Herschel's observations were done with a smaller , reflector. Nonetheless, the 40-foot caught the public imagination. It inspired scientists and writers including Erasmus Darwin and
William Blake William Blake (28 November 1757 – 12 August 1827) was an English poet, painter, and printmaker. Largely unrecognised during his life, Blake is now considered a seminal figure in the history of the poetry and visual art of the Romantic Age. ...
, and impressed foreign tourists and French dignitaries. King George was pleased. 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 20-foot telescope

In 2012, the
BBC #REDIRECT BBC #REDIRECT BBC Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
...
television programme ''
Stargazing Live ''Stargazing Live'' is a British live television programme on astronomy that was broadcast yearly on BBC Two over three nights every winter from 2011 to 2017. The series was primarily presented by scientist Brian Cox and comedian and amateur a ...
'' 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 , mottoeng = Experience is the best teacher , established = 1851 – Teacher Training College1992 – gained university status , type = Public , chancellor = William Cavendish, Ea ...
where it will be used for educational purposes.


Life on other celestial bodies

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. During 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 as to speculate that the interior of the Sun was populated.


Sunspots, climate and wheat yields

Herschel examined the correlation of
solar variation The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
and
solar cycle The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
and climate. Over a period of 40 years (1779–1818), Herschel 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 The Dalton Minimum was a period of low sunspot count, representing low solar activity, named after the English meteorologist John Dalton, lasting from about 1790 to 1830 or 1796 to 1820, corresponding to the period solar cycle 4 to solar cycle ...
, 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 Adam Smith (baptized 1723 – 17 July 1790) was a Scottish economist and philosopher who was a pioneer in the thinking of political economy and key figure during the Scottish Enlightenment. Seen by some as "The Father of Economics"——— ...
in ''
The Wealth of Nations ''An Inquiry into the Nature and Causes of the Wealth of Nations'', generally referred to by its shortened title ''The Wealth of Nations'', is the ''magnum opus'' of the Scottish economist and moral philosopher Adam Smith. First published in 1 ...
''. 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 William Stanley Jevons (; 1 September 183513 August 1882) was an English economist and logician. Irving Fisher described Jevons's book ''A General Mathematical Theory of Political Economy'' (1862) as the start of the mathematical method in ec ...
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.


Further discoveries

In his later career, Herschel discovered two moons of Saturn, Mimas and
Enceladus Enceladus is the sixth-largest moon of Saturn (19th largest in the Solar System). It is about in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most refle ...
; as well as two moons of Uranus, Titania and
Oberon Oberon () is a king of the fairies in medieval and Renaissance literature. He is best known as a character in William Shakespeare's play ''A Midsummer Night's Dream'', in which he is King of the Fairies and spouse of Titania, Queen of the Fairi ...
. He did not give these moons their names; they were named by his son
John John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Secon ...
in 1847 and 1852, respectively, after his death. Herschel measured the
axial tilt In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbi ...
of
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
and discovered that the Martian ice caps, first observed by
Giovanni Domenico Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the ...
(1666) and
Christiaan Huygens Christiaan Huygens, Lord of Zeelhem, ( , , ; also spelled Huyghens; la, Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor, who is regarded as one of the greatest scientists of ...
(1672), changed size with that planet's seasons. It has been suggested that Herschel discovered rings around Uranus. Herschel introduced but did not create the word "
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...
", meaning ''star-like'' (from the Greek ''asteroeides'', ''aster'' "star" + ''-eidos'' "form, shape"), in 1802 (shortly after Olbers discovered the second
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
, 2 Pallas, in late March), to describe the star-like appearance of the small moons of the
giant planets The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials (volatiles), rather than rock or other solid matter, but massive solid planets can also exist. The ...
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 Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
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 The solar apex, or the apex of the Sun's way, refers to the direction that the Sun travels with respect to the local standard of rest. This is not to be confused with the Sun's apparent motion through all constellations of the zodiac, which is ...
to
Lambda Herculis Lambda Herculis (λ Herculis. abbreviated Lambda Her, λ Her), formally named Maasym , is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the S ...
, only 10° away from today's accepted position. Herschel also studied the structure of the
Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...
and was the first to propose a model of the galaxy based on observation and measurement. He concluded that it was in the shape of a
disk Disk or disc may refer to: * Disk (mathematics), a geometric shape * Disk storage Music * Disc (band), an American experimental music band * ''Disk'' (album), a 1995 EP by Moby Other uses * Disk (functional analysis), a subset of a vector sp ...
, but incorrectly assumed that the Sun was in the centre of the disk. This
heliocentric Heliocentrism (also known as the Heliocentric model) is the astronomical model in which the Earth and planets revolve around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism, which placed the Earth at ...
view was eventually replaced by
galactocentrism In astronomy, galactocentrism is the theory that the Milky Way Galaxy, home of Earths Solar System, is at or near the center of the Universe. Thomas Wright and Kant first speculated that fuzzy patches of light called nebulae were actually dista ...
due to the work of
Harlow Shapley Harlow Shapley (November 2, 1885 – October 20, 1972) was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal. Shapley used Cepheid variable stars to estim ...
,
Heber Doust Curtis Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer. He participated in 11 expeditions for the study of solar eclipses, and, as an advocate and theorist that additional galaxies existed outside of the Milky Way, wa ...
and
Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects ...
in the 20th century. All three men used significantly more far-reaching and accurate telescopes than Herschel's.


Discovery of infrared radiation in sunlight

In early 1800, Herschel was testing different filters to pass
sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...
through, and noticed that filters of different colors seemed to generate varying amounts of heat. He decided to pass the light through a
prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...
to measure the different colors of light using a
thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
, and in the process, took a measurement just beyond the red end of the
visible spectrum The visible spectrum is the portion of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' or simply light. A typical human eye wil ...
. He detected a temperature one degree higher than that of red light. Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum. He published these results in April 1800.


Biology

Herschel used a
microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...
to establish that
coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...
was not a plant – as many at the time believed – because it lacked the cell walls characteristic of plants. It is in fact an animal, a
marine invertebrate Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have evo ...
.


Family and death

On 8 May 1788, William Herschel married the widow Mary Pitt (née Baldwin) at St Laurence's Church, Upton in Slough. They had one child,
John John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Secon ...
, 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 The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...
in 1788. In 1816, William was made a Knight of the
Royal Guelphic Order The Royal Guelphic Order (german: Königliche Guelphen-Orden), sometimes referred to as the Hanoverian Guelphic Order, is a Hanoverian order of chivalry instituted on 28 April 1815 by the Prince Regent (later King George IV). It takes its name ...
by the
Prince Regent A prince regent or princess regent is a prince or princess who, due to their position in the line of succession, rules a monarchy as regent in the stead of a monarch regnant, e.g., as a result of the sovereign's incapacity (minority or illness ...
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 (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NGO ...
. In 1813, he was elected a foreign member of the
Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special ...
. 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 Caroline was deeply distressed by his death, and soon after his burial she returned to
Hanover Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German state of Lower Saxony. Its 535,932 (2021) inhabitants make it the 13th-largest city in Germany as well as the fourth-largest city in Northern Germany ...
, 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 Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...
, 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 The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...
''. She died on 9 January 1848.


Memorial

William Herschel lived most of his life in the town of
Slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...
, then in Buckinghamshire (now in Berkshire). He died in the town and was buried under the tower of the Church of St Laurence, Upton-cum-Chalvey, near Slough. Herschel is especially honoured 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. His house at 19 New King Street in
Bath, Somerset Bath () is a city in the Bath and North East Somerset unitary area in the county of Somerset, England, known for and named after its Roman-built baths. At the 2021 Census, the population was 101,557. Bath is in the valley of the River Avon, ...
, where he made many
telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...
s and first observed Uranus, is now home to the Herschel Museum of Astronomy. There is a memorial near the choir screen in
Westminster Abbey Westminster Abbey, formally titled the Collegiate Church of Saint Peter at Westminster, is an historic, mainly Gothic church in the City of Westminster, London, England, just to the west of the Palace of Westminster. It is one of the United ...
.


Musical works

Herschel's complete musical works were as follows: * 18 symphonies for small orchestra (1760–1762) * 6 symphonies for large orchestra (1762–1764) * 12
concerto A concerto (; plural ''concertos'', or ''concerti'' from the Italian plural) is, from the late Baroque era, mostly understood as an instrumental composition, written for one or more soloists accompanied by an orchestra or other ensemble. The typi ...
s for
oboe The oboe ( ) is a type of double reed woodwind instrument. Oboes are usually made of wood, but may also be made of synthetic materials, such as plastic, resin, or hybrid composites. The most common oboe plays in the treble or soprano range. A ...
,
violin The violin, sometimes known as a ''fiddle'', is a wooden chordophone (string instrument) in the violin family. Most violins have a hollow wooden body. It is the smallest and thus highest-pitched instrument (soprano) in the family in regular ...
and
viola The viola ( , also , ) is a string instrument that is bow (music), bowed, plucked, or played with varying techniques. Slightly larger than a violin, it has a lower and deeper sound. Since the 18th century, it has been the middle or alto voice of ...
(1759–1764) * 2 concertos for organ * 6 sonatas for violin,
cello The cello ( ; plural ''celli'' or ''cellos'') or violoncello ( ; ) is a Bow (music), bowed (sometimes pizzicato, plucked and occasionally col legno, hit) string instrument of the violin family. Its four strings are usually intonation (music), t ...
and
harpsichord A harpsichord ( it, clavicembalo; french: clavecin; german: Cembalo; es, clavecín; pt, cravo; nl, klavecimbel; pl, klawesyn) is a musical instrument played by means of a keyboard. This activates a row of levers that turn a trigger mechanism ...
(published 1769) * 12 solos for violin and
basso continuo Basso continuo parts, almost universal in the Baroque era (1600–1750), provided the harmonic structure of the music by supplying a bassline and a chord progression. The phrase is often shortened to continuo, and the instrumentalists playing th ...
(1763) * 24 capriccios and 1 sonata for solo violin * 1
andante Andante may refer to: Arts * Andante (tempo), a moderately slow musical tempo * Andante (manga), ''Andante'' (manga), a shōjo manga by Miho Obana * Andante (song), "Andante" (song), a song by Hitomi Yaida * "Andante, Andante", a 1980 song by A ...
for two basset horns, two oboes, two
horn Horn most often refers to: *Horn (acoustic), a conical or bell shaped aperture used to guide sound ** Horn (instrument), collective name for tube-shaped wind musical instruments *Horn (anatomy), a pointed, bony projection on the head of various ...
s and two
bassoon The bassoon is a woodwind instrument in the double reed family, which plays in the tenor and bass ranges. It is composed of six pieces, and is usually made of wood. It is known for its distinctive tone color, wide range, versatility, and virtuo ...
s. Various vocal works including a "
Te Deum The "Te Deum" (, ; from its incipit, , ) is a Latin Christian hymn traditionally ascribed to AD 387 authorship, but with antecedents that place it much earlier. It is central to the Ambrosian hymnal, which spread throughout the Latin Ch ...
",
psalm The Book of Psalms ( or ; he, תְּהִלִּים, , lit. "praises"), also known as the Psalms, or the Psalter, is the first book of the ("Writings"), the third section of the Tanakh, and a book of the Old Testament. The title is derived ...
s,
motet In Western classical music, a motet is mainly a vocal musical composition, of highly diverse form and style, from high medieval music to the present. The motet was one of the pre-eminent polyphonic forms of Renaissance music. According to Margar ...
s and sacred chants along with some
catches Catch may refer to: In sports * Catch (game), children's game * Catch (baseball), a maneuver in baseball * Catch (cricket), a mode of dismissal in cricket * Catch or reception (gridiron football) * Catch, part of a rowing stroke In music * Cat ...
. Keyboard works for organ and harpsichord: * 6 fugues for organ * 24 sonatas for organ (10 now lost) * 33 voluntaries and pieces for organ (incomplete) * 24 pieces for organ (incomplete) * 12 voluntaries (11 now lost) * 12 sonatas for harpsichord (9 extant) * 25 variations on an ascending scale * 2
minuet A minuet (; also spelled menuet) is a social dance of French origin for two people, usually in time. The English word was adapted from the Italian ''minuetto'' and the French ''menuet''. The term also describes the musical form that accomp ...
s for harpsichord


Named after Herschel

* The
astrological symbol Historically, astrological and astronomical symbols overlapped. Frequently used symbols include signs of the zodiac and classical planets. These originate from medieval Byzantine codices. Their current form is a product of the European Renaissan ...
for planet
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
() features the capital initial letter of Herschel's surname. *
Mu Cephei Mu Cephei ( Latinized from μ Cephei, abbreviated Mu Cep or μ Cep), also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at ...
is also known as Herschel's Garnet Star * Herschel, a crater on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
* Herschel, a large
impact basin An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...
on
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
* The enormous crater Herschel on
Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
's moon Mimas * The Herschel gap in Saturn's rings. * 2000 Herschel, an asteroid * The
William Herschel Telescope The William Herschel Telescope (WHT) is a optical/near-infrared reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands, Spain. The telescope, which is named after William Hersc ...
on
La Palma La Palma (, ), also known as ''La isla bonita'' () and officially San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of making it the fifth largest of the eight main Canary Islands. The ...
* The Herschel Space Observatory, successfully launched by the European Space Agency on 14 May 2009. It is the largest
space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launch ...
of its kind *
Herschel Grammar School Herschel Grammar School is a co-educational grammar school with academy status, located in Slough, Berkshire, England. The headteacher is Mrs Joanne Rockall. The school has around 900 pupils, 250 of whom are in the sixth form. History The ...
, Slough * Rue Herschel, a street in the
6th arrondissement of Paris The 6th arrondissement of Paris (''VIe arrondissement'') is one of the 20 Arrondissements of Paris, arrondissements of the capital city of France. In spoken French, it is referred to as ''le sixième''. The arrondissement, called Luxembourg in ...
. * The Herschel Building at
Bath College Bath College is a Further Education college in the centre of Bath, Somerset Bath () is a city in the Bath and North East Somerset unitary area in the county of Somerset, England, known for and named after its Roman-built baths. At the 2 ...
, Bath * The Herschel building at
Newcastle University Newcastle University (legally the University of Newcastle upon Tyne) is a UK public university, public research university based in Newcastle upon Tyne, North East England. It has overseas campuses in Singapore and Malaysia. The university is ...
, Newcastle, United Kingdom * Herschel Museum of Astronomy, at 19 New King Street in Bath. * Herschelschule, Hanover, Germany, a grammar school * The Herschel Observatory, at the Universitas School in Santos,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
. * The lunar crater C. Herschel, the asteroid 281 Lucretia, and the comet 35P/Herschel-Rigollet are named after his sister
Caroline Herschel Caroline Lucretia Herschel (; 16 March 1750 – 9 January 1848) was a German born British astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigolle ...
. * The public house "Herschel Arms" at 22 Park Street,
Slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...
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 Eton ( ) is a town in Berkshire, England, on the opposite bank of the River Thames to Windsor, connected to it by Windsor Bridge. The civil parish, which also includes the village of Eton Wick two miles west of the town, had a population of 4 ...
. * Herschel Park, Slough. * The shape of Slough Bus Station, built in 2011, was inspired by Herschel's infrared experiment. * Herschel Street, a street in Brisbane, Australia.


See also

*
Catalogue of Nebulae and Clusters of Stars The ''Catalogue of Nebulae and Clusters of Stars'' (CN) is an astronomical catalogue of nebulae first published in 1786 by William Herschel, with the assistance of his sister Caroline Herschel. It was later expanded into the ''General Catalogue o ...
*
German inventors and discoverers ---- __NOTOC__ This is a list of German inventors and discoverers. The following list comprises people from Germany or German-speaking Europe, and also people of predominantly German heritage, in alphabetical order of the surname. For the li ...
*
List of astronomical instrument makers The following is a list of astronomical instrument makers, along with lifespan and country of work, if available. A B C D E F G H I J K L M N O P Q R S T U V ...
*
List of largest optical telescopes historically Telescopes have grown in size since they first appeared around 1608. The following tables list the increase in size over the years. Different technologies can and have been used to build telescopes, which are used to magnify distant views especia ...
*
NGC 4800 NGC 4800 is an isolated spiral galaxy in the constellation Canes Venatici, located at a distance of from the Milky Way. It was discovered by William Herschel on April 1, 1788. The morphological classification of this galaxy is SA(rs)b, indicat ...
* NGC 4694


References


Sources

* * *


Further reading

* "William Herschel" by Michael Hoskin. ''New Dictionary of Scientific Biography'' Scribners, 2008. v. 3, pp. 289–291.
Biography: JRASC 74 (1980) 134


External links

* *
Articles and letters published in the ''Philosophical Transactions'' and available online
(70 items, June 2016)



* Full text of * Full text of
The Story of the Herschels
' (1886) from
Project Gutenberg Project Gutenberg (PG) is a Virtual volunteering, volunteer effort to digitize and archive cultural works, as well as to "encourage the creation and distribution of eBooks." It was founded in 1971 by American writer Michael S. Hart and is the ...

Portraits of William Herschel
at the
National Portrait Gallery (United Kingdom) The National Portrait Gallery (NPG) is an art gallery in London housing a collection of portraits of historically important and famous British people. It was arguably the first national public gallery dedicated to portraits in the world when it ...

Herschel Museum of Astronomy
located in his Bath home
William Herschel Society

''The Oboe Concertos of Sir William Herschel'', Wilbert Davis Jerome ed.
*
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 November 2008, Fermilab Colloquium

* * Musical pieces by William Herschel @YouTube: ** ** (Chamber Symphony in F, 2nd movement) ** ** ** ** {{DEFAULTSORT:Herschel, Friedrich Wilhelm 1738 births 1822 deaths 19th-century British astronomers 18th-century classical composers 18th-century British astronomers 18th-century German astronomers Uranus British male classical composers British Lutherans German classical oboists Male oboists German Lutherans Classical-period composers Discoverers of moons Fellows of the Royal Society Members of the Royal Swedish Academy of Sciences Honorary members of the Saint Petersburg Academy of Sciences Scientists from Hanover Composers awarded knighthoods Recipients of the Copley Medal British scientific instrument makers British classical organists British male organists German organists German emigrants to the Kingdom of Great Britain 18th-century German composers 18th-century British male musicians 19th-century German male musicians Discoverers of astronomical objects Burials in Berkshire Fellows of the American Academy of Arts and Sciences Presidents of the Royal Astronomical Society 18th-century keyboardists German male classical composers German classical composers German emigrants to England German military personnel of the Seven Years' War Deserters
William William is a male given name of Germanic origin.Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 276. It became very popular in the English language after the Norman conquest of Engl ...
Male classical organists