Wilhelm Herschel

William Herschel.
Painting by Lemuel Francis Abbott (1785, oil on canvas, 76.5 × 63.5 cm, National Portrait Gallery , London)

Herschel's former home in Bath, now a memorial

Friedrich Wilhelm Herschel ( English William Herschel ; born November 15, 1738 in Hanover , † August 25, 1822 in Slough ) was a German-British astronomer and musician .

Life

Herschel was the son of the military musician Issak Herschel and his wife Anna Ilse Moritzen. Friedrich Wilhelm joined the Electorate of Hanover as an oboist and violinist at the age of 14 . He began to be interested in mathematics and languages ​​at a young age . When the Seven Years' War broke out , before the French troops occupied Hanover in 1757, his regiment was transferred to England, which at the time was linked to his home country Hanover in personal union. In autumn 1756 he returned with the regiment to his homeland, but in the same year, after he had left the army, he returned to London with his brother Jacob Herschel, who was also a musician . There he found a job as a copyist. From 1760 he acted as an instructor of the Durham Militia , got the rank of director of the subscription concerts in Leeds in 1762 and turned to Halifax in 1766 to work there for a few months as organist at the local Parish Church.

The city of Bath (Somerset) was one of the centers of social and cultural life in England at that time. Wilhelm Herschel soon joined the orchestra there, which was one of the best in England, and became its director that same year. At the same time he held the office of organist at the Bather Octagon Chapel from October 1766 . Outside the season in Bath he gave guest performances with his orchestra at the Theater Royal in Bristol ; there and in Bath he directed the oratorios during Lent . He wrote the majority of his larger compositions between 1759 and 1769. From 1772 onwards, his younger sister Caroline Herschel also lived with him in Bath, who from then on ran the household for him and appeared as a singer at his concerts.

Wilhelm and Caroline Herschel polishing a telescope mirror

At the beginning of the 1770s, Wilhelm Herschel turned more and more to astronomy. Inspired by studying mathematical music theory , he dealt with mathematics and the construction and sale of astronomical instruments. With the study of astronomical works his interest in astronomy grew, which for him extended not only to the observation of the moon , planets and comets . Rather, he wanted to study the objects of the fixed star sky and even create a complete list of all visible stars and nebulae . However, the telescopes and reflector telescopes common around 1770 were not technically capable of doing this. Therefore, he began to build mirror telescopes himself, which he succeeded after initial failures. For the mirror he used the alloy speculum . From 1766 onwards he manufactured numerous telescopes with constantly growing diameters (and thus greater resolution ). Herschel was assisted in his observations by his brother Alexander and sister Caroline Herschel , who later became a recognized astronomer.

In 1780 Herschel became director of the orchestra in Bath, and he was also accepted as a member of the newly formed Bath Literary and Philosophical Society .

Herschel suddenly became famous when he discovered a new object in the solar system in 1781 : the planet Uranus , which he initially named in honor of the English king Georgium Sidus (Georg's star). He was elected a member of the Royal Society of London. King George III promised him an annual pension of £ 200, which enabled him to leave his musical activities and devote himself entirely to astronomy. In 1785 he moved to Old Windsor and a year later to Slough. In the years that followed, Herschel manufactured telescopes not only for his own use, but also to increase his income. Since 1785 he was a member of the American Philosophical Society . In 1786 he was elected a foreign member of the Göttingen Academy of Sciences and in 1788 of the American Academy of Arts and Sciences . Also in 1788 he married Mary Pitt, the widow of one of his neighbors. His only son, John Frederick William Herschel (1792–1871) later also became an important astronomer. Joseph Haydn was among the many personalities who visited Herschel in 1791 . From 1789 he was a member of the Académie des Sciences in Paris. In 1793 he was elected a member of the Leopoldina ; in the same year he acquired British citizenship and has been called William ever since. In 1816 he was the Prince Regent , the future King George IV. , As a Knight of the Guelph-order to defeat Knight . In 1820 he was elected the first president of the Royal Astronomical Society , which his son John founded with Charles Babbage and others. He lived and worked in Slough until his death in 1822. Herschel was buried in St. Laurence's Chapel in Upton, Slough. On his tombstone is the Latin phrase Caelorum perrupit claustra ("He broke through the boundaries of heaven").

In 1935 the moon crater Herschel was named after him. In 1973 the Herschel Crater was jointly baptized after him and his son, Sir John Herschel . The largest crater on the Saturn moon Mimas, which he discovered, has been named Herschel since 1982 , and the asteroid (2000) Herschel , discovered in 1960, was named after him. The ESA named her in 2009 launched space telescope after him. There is a bust of him in the Walhalla near Regensburg.

Discoveries

Uranus, moons, rings and nebulae

Depiction of Wilhelm and Caroline Herschel on the night Uranus was discovered.

Dr. Herschel (1814) - This dotted engraving by James Godby based on a model by Friedrich Rehberg shows Herschel in front of the constellation of Gemini , in which he discovered the “new” planet Uranus in 1781. The winter night sky as a backdrop lets Herschel appear as "romantic wise men".

Since prehistoric times, people have only known the five closest planets to the sun and earth thanks to the clear-eyed starry sky : Mercury , Venus , Mars , Jupiter and Saturn . On March 13, 1781, during a systematic survey of the sky with a self-made reflector telescope, Herschel discovered an object that struck him with its clearly planar appearance. At first he thought of a comet. But then he realized that it had to be a planet and named it georgium sidus ( St. George's star ), after the English king who was ruling at the time. But since all the planets known in the sky at that time had a Latin name from Greco-Roman mythology, it was renamed Uranus. With this discovery, the spatial extent of the solar system had doubled. After the two moons Titania and Oberon (both 1787), Herschel discovered the ring system of Uranus in 1797, but this was dismissed as an error until its rediscovery in 1977. The sightings of Saturn's moons Mimas and Enceladus can also be attributed to him.

Herschel's interest, however, was in the misty celestial objects. Charles Messier had published a catalog in 1780/81 with 103 non-punctiform ("foggy") appearing objects; the experts disagreed as to whether they were countless stars or glowing clouds or liquids. From autumn 1782 onwards, Herschel looked specifically for other objects of this type (until 1802). With his superior device he soon found that he could resolve several of the “nebulae” into single stars. He suspected that the other objects were also star clusters and could only not be resolved because they were much further away - and therefore much larger - than previously thought. This assumption made in 1785 has proven to be correct in principle. However, Herschel could not yet know that the types were fundamentally different: real glowing gas nebulae (such as the Orion Nebula ), star clusters (such as the Pleiades or M13 ) and galaxies (such as the Andromeda Nebula ).

Nebula classification and Milky Way statistics

Herschel was the first to introduce a classification of these objects. In his fog catalogs he differentiated them according to their apparent brightness , size, regularity of shape and concentration towards the center. In the course of his investigations, he developed a theory of the formation of star clusters: Over time, gravity has caused more densely packed systems to emerge from loose clusters. So he introduced the concept of development (or evolution) into astronomy: the starry sky was no longer eternal and immutable. Herschel thus became the founder of the field of cosmology .

When he observed a fixed star with a surrounding cloud in 1790, he revised his earlier view. He now thought it possible that all the stars would have contracted under the influence of gravity from a kind of cloud of gas or liquid.

He was also the first astronomer to use statistics and probability considerations: He found that a piece of the Milky Way , 15 ° long and 2 ° wide, contains more than 50,000 clearly recognizable stars. He tried to derive the shape of the Milky Way from the distribution of the fixed stars and their number in calibration fields of equal size . He came to the conclusion that it was a lenticular cluster of stars. Since he assumed that all fixed stars had the same absolute brightness , he believed that he could deduce the distance from the apparent brightness. This approach later turned out to be wrong. Herschel also made the first attempts to determine the movement of the solar system in space - a work that was only carried out by Argelander et al. a. could be successfully tackled with sharper telescopes.

He also found that not all double stars could only be arranged randomly (visual double stars). Rather, there had to be a considerable number bound together by gravity (physical binary stars). He was able to observe the circular motion of some of these pairs of stars and began systematically comparing the brightness of the components.

Double stars and light spectrum

In the course of time he created a catalog of foggy objects with more than 2500 entries (called the "Herschel catalog") and a catalog with 848 double stars. Without the selfless help of his sister Caroline these catalogs would not have come about.

He discovered the Uranus moons Titania and Oberon as well as the Saturn moons Mimas and Enceladus - making him the only lunar discoverer of the 18th century. He determined the period of rotation for Saturn and demonstrated seasonal changes for Mars . From observing the Lomonosov effect , he concluded that Venus must have an atmosphere. Lomonossow had already suspected this in 1761, but did not publish it.

Herschel discovered infrared radiation in 1800 by directing sunlight through a prism and placing a thermometer behind the red end of the visible spectrum . The temperature rose in this area, and Herschel concluded that an invisible form of energy must be operating there.

Herschel's observations were only possible due to the extraordinary light output of his telescopes, but were impaired by their inadequate sharpness. He was an extraordinarily talented and tireless observer; his solutions were (sometimes too) bold, but always groundbreaking.

Sunspots and Climate

Herschel suspected an influence of cyclical changes in solar radiation on the climate. He was the first to try to quantify the alleged connection. To this end, he compared historical observations of sunspots and, as an indicator of the climate, the development of London wheat prices, which he took from Adam Smith's work " The Wealth of Nations ". He found five periods when low prices coincided with many sunspot observations, and five when there were high prices and few sunspot observations. He concluded that a few sunspots could indicate a “deficit of the sun's rays”.

“The result of this review of the foregoing five periods is, that, from the price of wheat, it seems probable that some temporary scarcity or defect of vegetation has generally taken place, when the sun has been without those appearances which we surmise to be symptoms of a copious emission of light and heat. "

- Sir William Herschel : Philosophical Transactions of the Royal Society of London. Volume 91, 1801, p. 265.

The thesis of a connection between climate and sunspots was the subject of ongoing discussions in the 19th century (see also sunspot theory ). Indeed, a high number of sunspots is an indicator of increased activity of the sun and higher radiation intensity, which tends to cause the earth to warm slightly. Even if the relation of the variables examined by Herschel is not significant according to modern statistical standards, his analysis was important for the history of ideas of solar-terrestrial influences.

Herschel's telescopes

Light path in a Herschel-Lomonosov reflecting telescope

18.7 inch telescope with 20 feet focal length

Wilhelm Herschel's 48-inch reflector telescope

Herschel invented an alternative to the side view of the Newton telescope because its mirrors were big enough for it. These writes Meyers encyclopedia 1885:

“With the giant telescopes by Herschel and Lord Rosse , the mirrors of which were 1–2 m in diameter, such a second mirror [note: secondary mirror ] and thus the loss of light it caused was avoided by a simple trick. The concave mirror (see Fig. 5) is namely a little inclined relative to the axis of the tube, so that the image comes to lie close to the edge of the mirror and can be viewed there through an ocular lens. In doing so, of course, the head of the observer partially steps in front of the opening of the tube, but this is of little importance given the large diameter of the mirror. Herschel called his instrument Front view telescop. H. Vornschaufernrohr. "

The procedure requires a comparatively low aperture ratio (mirror diameter / focal length ). The tilting of the main mirror against the optical axis of the telescope otherwise leads to strong imaging errors (see Schiefspiegler ).

Of the multitude of telescopes that Herschel built and used, the following are particularly noteworthy:

• Herschel discovered the planet Uranus with a reflecting telescope 6 inches (about 15 cm) in diameter and 7 feet (about 210 cm) focal length.
• For his nebula catalog, he mainly used a device with an 18.7 inch (47.5 cm) mirror diameter and 20 feet (6.1 m) focal length (from 1783).
• His largest telescope (see picture) was built under his supervision in 1789 and had a mirror diameter of 48 inches (122 cm) and a length of 40 feet (12 m). The aperture ratio was about 1:10. It was only surpassed by Lord Rosses " Leviathan " two generations later . The 48-inch telescope was destroyed by a storm in 1839.

Herschel only built mirror telescopes . Their mirrors were cast from a metal alloy ( speculum ) and often had to be repolished as they tarnished easily.

Herschel as a musician and composer

In addition to the violin, Herschel also played the cello , oboe and organ . His first musical works are still entirely in the tradition of the north German sensitive style ; the associated aspects such as rapid dynamic changes and small-scale changes in the musical structure are particularly noticeable in the first oboe concerto in E flat major and in the first viola concerto in D minor (both from 1759). Applications of counterpoint and sudden harmonic developments with chromatics can also be found in his early works. Probably through suggestions from the compositions of Johann Christian Bach and Carl Friedrich Abel , he later came to a gallant musical style with often simple harmony. "What is striking in these works are the sometimes differentiated sound effects and the efforts of the composer to create an inner connection through a motivic relationship in multi-movement works."

Musical works

• Symphonies
  • Symphonies No. 1–6 in G major, D major, C major, D minor, F minor, B major; Instrumentation: 2 violins, viola, cello and double bass obligato and 2 violins, 2 bassoons and harpsichord in ripieno (1760)
  • Symphonies No. 7–12 in D minor, C minor, F major, G minor, F minor, D major with the same scoring as the symphonies 1–6 (1761)
  • Symphonies No. 13-18 in D major, D major, E flat major, E flat major, C major, E flat major in the same instrumentation as the symphonies 1–6 (1762)
  • Symphonies No. 19–24 in C minor, C major, B minor, A minor, D major, C major in the same instrumentation as the symphonies 1–6 and extended wind section (1762–1764)
  • Symphony in E minor (1761), only a few parts survive
• Concerts
  • Concerto in E flat major for oboe, strings and figured bass (1759)
  • Concerto in C major for oboe, strings and 2 horns (around 1760–1762)
  • Concerto in C major for oboe, strings, 2 horns and 2 bassoons (around 1760–1762)
  • Concert movement in C major for oboe, strings and 2 horns (around 1760–1762)
  • Concerto in A minor for violin, strings, bassoon and figured bass (1760)
  • Concerto in G major for violin, strings and figured bass (1761)
  • Concerto in C major for violin and strings (1762)
  • Concerto in D minor for violin and strings (1764)
  • Concerto in D minor for viola, strings and figured bass (1759)
  • Concerto in F major for viola, strings and figured bass (1759)
  • Concerto in C major for viola and strings (1761/62 at the earliest), incomplete
  • Concerto in D major for organ and strings (1767)
  • Concerto in G major for organ and orchestra (1767)
  • Andante in G major for organ and strings
• Chamber music
  • 12 solos for violin and figured bass (around 1763)
  • 6 sonatas for harpsichord, with violin and violoncello ad libitum, Bath (1769)
  • Andantino for 2 basset horns, 2 oboes and 2 bassoons
  • 24 capriccios for violin solo (1763)
  • 3 sonatas for harpsichord, with violin and violoncello ad libitum
  • "25 Variations upon the Ascending Scale" for keyboard instrument
  • "Miss Shafto's Minuet" in D major and "Miss Hudson's Minuet" in G major for harpsichord
• Organ works
  • 6 fugues for organ
  • 24 sonatas for organ, 14 of which have survived
  • 33 “Voluntaries” and “Full Pieces”, incomplete
  • 24 "full pieces", incomplete
  • 12 “Voluntaries”, of which 1 received

Fonts (selection)

• XVIII. Description of a Forty-feet Reflecting Telescope. In: Philosophical Transactions of the Royal Society of London. Volume 85, London January 1795, pp. 347-409 ( doi: 10.1098 / rstl.1795.0021 ; full text ).
• Account of a Comet. In: Philosophical Transactions of the Royal Society of London. Volume 71, London January 1781 71, pp. 492-501 ( doi: 10.1098 / rstl.1781.0056 ; full text ).
• An Account of the Discovery of Two Satellites Revolving Round the Georgian Planet. In: Philosophical Transactions of the Royal Society of London. Volume 77, London January 1787 pp. 125–129 ( doi: 10.1098 / rstl.1787.0016 ; full text )
• Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure. In: Philosophical Transactions of the Royal Society of London. Volume 80, London January 1790, pp. 1–20 ( doi: 10.1098 / rstl.1790.0001 ; full text )
• About the construction of heaven. Treatises on the structure of the universe and the development of the heavenly bodies 1784–1814. Edited by Jürgen Hamel . Harri Deutsch Verlag, Frankfurt a. M. 2001 (= Ostwald's classic of the exact sciences. Volume 288). ISBN 3-8171-3288-3 .

literature

• Matthias Blazek: Astronomical personalities from Hanover: Caroline and William Herschel - the most famous star explorers of their time. In: home country. Journal of the Heimatbund Lower Saxony. Issue 2, June 2012, pp. 55–58.
• Karl Christian Bruhns :  Herschel, Friedrich Wilhelm . In: Allgemeine Deutsche Biographie (ADB). Volume 12, Duncker & Humblot, Leipzig 1880, pp. 227-238.
• Agnes Mary Clerke:  Herschel, William . In: Leslie Stephen, Sidney Lee (Eds.): Dictionary of National Biography . Volume 26:  Henry II - Hindley. MacMillan & Co, Smith, Elder & Co., New York City / London, 1891, pp 268 - 274 (English).
• Julius Dick:  Herschel, Friedrich Wilhelm. In: New German Biography (NDB). Volume 8, Duncker & Humblot, Berlin 1969, ISBN 3-428-00189-3 , pp. 695-698 ( digitized version ).
• Heinz Gärtner: He broke through the barriers of heaven. The life of Friedrich Wilhelm Herschel . Edition Leipzig, Leipzig 1996, ISBN 3-361-00461-6 .
• Jürgen Hamel: Friedrich Wilhelm Herschel. Leipzig 1988 (= biographies of outstanding natural scientists, technicians and physicians. 89), ISBN 3-322-00482-1 .
• Richard Holmes: The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science. HarperPress, London 2008, ISBN 978-0-00-714952-0 .
• Michael Hoskin: Discoverers of the Universe. William and Caroline Herschel. Princeton University Press, Princeton / Oxford 2011, ISBN 978-0-691-14833-5 .
• Michael Hoskin: Herschel, William (1738-1822), musician and astronomer. In: Henry Colin Gray Matthew, Brian Harrison (Eds.): Oxford Dictionary of National Biography , from the earliest times to the year 2000 (ODNB). Oxford University Press, Oxford 2004, ISBN 0-19-861411-X , ( oxforddnb.com license required ), as of January 2008
• Herschel, Sir Frederick William . In: Encyclopædia Britannica . 11th edition. tape 13 : Harmony - Hurstmonceaux . London 1910, p. 391 (English, full text [ Wikisource ]).
• O. Gingerich: William Herschel's 1784 Autobiography. In: Harvard Library Bulletin. No. 32, 1984, pp. 73-82.
• W. Birtel: The Viola Concertos by Friedrich Wilhelm Herschel. In: Das Orchester , No. 42/4, 1994, pp. 6–9.
• H. Gärtner: He broke through the barriers of heaven. The life of Friedrich Wilhelm Herschel. Leipzig 1996.
• MA Hoskin: Herschel, William . In: Charles Coulston Gillispie (Ed.): Dictionary of Scientific Biography . tape 6 : Jean Hachette - Joseph Hyrtl . Charles Scribner's Sons, New York 1972, p. 328-336 .

Web links

Commons : Wilhelm Herschel  - Album with pictures, videos and audio files

Wikisource: Wilhelm Herschel  - Sources and full texts

• Literature by and about Wilhelm Herschel in the catalog of the German National Library
• Works by and about Wilhelm Herschel  in the German Digital Library
• Entry to Herschel; Sir; William (1738-1822); Astronomer in the Archives of the Royal Society , London
• Friedrich Wilhelm Herschel and the double stars
• Ingeborg Lechner: The work of the Herschel family (PDF) detailed biography of several family members
• Detailed biography of Herschel
• Publications by W. Herschel in the Astrophysics Data System
• Sheet music and audio files by Wilhelm Herschel in the International Music Score Library Project

Individual evidence

1. ↑ on the ancestors from Pirna see Jürgen Hamel: A contribution to the family history of Friedrich Wilhelm Herschel. The astronomer's stem series based on the sources. Notices from the Archenhold Observatory Berlin-Treptow, No. 164, Berlin 1989.
2. ^ Member History: Sir William Herschel. American Philosophical Society, accessed September 29, 2018 . 
3. ↑ Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 112.
4. ^ Georg Christoph Hamberger , Johann Georg Meusel , Johann Wilhelm Sigismund Lindner : The learned Teutschland: or, Lexicon of the now living Teutschen writers . tape 22 , part 2. Meyersche Hofbuchhandlung, Lemgo 1831, p. 719 ( full text in Google Book Search).
5. ↑ Herschel on the moon in the Gazetteer of Planetary Nomenclature of the IAU (WGPSN) / USGS
6. ^ Herschel on Mars in the IAU's Gazetteer of Planetary Nomenclature (WGPSN) / USGS
7. ↑ Herschel on the Mimas in the Gazetteer of Planetary Nomenclature of the IAU (WGPSN) / USGS
8. ↑ Fact Sheet. In: ESA Science & Technology. ESA, April 29, 2013, accessed on August 2, 2018 . 
9. ↑ Holmes, The Age of Wonder , p. 122 (ill.).
10. ↑ Uranus ring already seen in the 18th century? Scienceticker.info, April 17, 2007.
11. ↑ ^{a b c} Jeffrey J. Love: On the insignificance of Herschel's sunspot correlation . In: Geophysical Research Letters . August 2013, doi : 10.1002 / grl.50846 (open access).
12. ^ The Monthly review. Reprinted by Ralph Griffiths, George Edward Griffiths, 1750, Original from the New York Public Library Digitized May 22, 2007.
13. ↑ quoted from Nir Shaviv in PhysicaPlus. No. 5 Cosmic Rays and Climate 2005 ( physicaplus.org.il ( Memento of October 16, 2013 in the Internet Archive )).
14. ↑ Ilya G. Usoskin: A History of Solar Activity over Millennia . In: Living Reviews in Solar Physics . February 2017, doi : 10.1007 / s41116-017-0006-9 (Open Access).
15. ↑ Telescope (dioptric and catoptric) . In: Meyers Konversations-Lexikon . 4th edition. Volume 6, Verlag des Bibliographisches Institut, Leipzig / Vienna 1885–1892, p. 151.
16. ^ William Herschel: Description of a Forty-Feet Reflecting Telescope . tape 85 . Philosophical Transactions of the Royal Society of London, London May 18, 1795, pp. 347–409 , JSTOR : 106961 ( archive.org - with images between p. 408 and 409).
17. ^ ^{A b} Gilbert Stöck, Charles W. Cudworth:  Herschel, William. In: Ludwig Finscher (Hrsg.): The music in past and present . Second edition, personal section, volume 8 (Gribenski - Hilverding). Bärenreiter / Metzler, Kassel et al. 2002, ISBN 3-7618-1118-7  ( online edition , subscription required for full access)
18. ↑ Marc Honegger, Günther Massenkeil (ed.): The great lexicon of music. Volume 4: Half a note - Kostelanetz. Herder, Freiburg im Breisgau a. a. 1981, ISBN 3-451-18054-5 .