Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German
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, moons, comets and galaxies – in either ...
,
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
On ...
,
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
, and
geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method 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 object ...
. A special type of mathematical functions were named
Bessel function
Bessel functions, first defined by the mathematician Daniel Bernoulli and then generalized by Friedrich Bessel, are canonical solutions of Bessel's differential equation
x^2 \frac + x \frac + \left(x^2 - \alpha^2 \right)y = 0
for an arbitrar ...
s after Bessel's death, though they had originally been discovered by
Daniel Bernoulli and then generalised by Bessel.
Life and family
Bessel was born in
Minden
Minden () is a middle-sized town in the very north-east of North Rhine-Westphalia, Germany, the greatest town between Bielefeld and Hanover. It is the capital of the district (''Kreis'') of Minden-Lübbecke, which is part of the region of De ...
,
Westphalia
Westphalia (; german: Westfalen ; nds, Westfalen ) is a region of northwestern Germany and one of the three historic parts of the state of North Rhine-Westphalia. It has an area of and 7.9 million inhabitants.
The territory of the regio ...
, then capital of the Prussian administrative region
Minden-Ravensberg, as second son of a civil servant into a large family. At the age of 14 Bessel was apprenticed to the import-export concern Kulenkamp at
Bremen
Bremen ( Low German also: ''Breem'' or ''Bräm''), officially the City Municipality of Bremen (german: Stadtgemeinde Bremen, ), is the capital of the German state Free Hanseatic City of Bremen (''Freie Hansestadt Bremen''), a two-city-state cons ...
. The business's reliance on cargo ships led him to turn his
mathematical skills to problems in
navigation
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation ...
. This in turn led to an interest in
astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
as a way of determining
longitude
Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...
.
Bessel came to the attention of a major figure of German astronomy at the time,
Heinrich Wilhelm Olbers, by producing a refinement on the orbital calculations for
Halley's Comet in 1804, using old observation data taken from
Thomas Harriot and
Nathaniel Torporley in 1607.
Franz Xaver von Zach edited the results in his journal ''Monatliche Correspondenz''.
Two years later Bessel left Kulenkamp and became assistant at
Johann Hieronymus Schröter's private observatory in
Lilienthal near
Bremen
Bremen ( Low German also: ''Breem'' or ''Bräm''), officially the City Municipality of Bremen (german: Stadtgemeinde Bremen, ), is the capital of the German state Free Hanseatic City of Bremen (''Freie Hansestadt Bremen''), a two-city-state cons ...
as successor of
Karl Ludwig Harding
Karl Ludwig Harding (29 September 1765 – 31 August 1834) was a German astronomer, who discovered 3 Juno, the third asteroid of the main-belt in 1804. The lunar crater '' Harding'' and the asteroid 2003 Harding are named in his honor.
...
. There he worked on
James Bradley's stellar observation data to produce precise positions for some 3,222 stars.
Despite lacking any higher education, especially at university, Bessel was appointed director of the newly founded
Königsberg Observatory
Koenigsberg Observatory (german: Sternwarte Königsberg; Königsberger Universitätssternwarte; obs. code: 058) was an astronomical observatory and research facility which was attached to the Albertina University in Königsberg, what is now Kal ...
by King
Frederick William III of Prussia
Frederick William III (german: Friedrich Wilhelm III.; 3 August 1770 – 7 June 1840) was King of Prussia from 16 November 1797 until his death in 1840. He was concurrently Elector of Brandenburg in the Holy Roman Empire until 6 August 1806, w ...
in January 1810, at the age of 25, and remained in that position until his death. On the recommendation of fellow mathematician and physicist
Carl Friedrich Gauss, with whom he corresponded from 1804 to 1843, he was awarded an honorary doctor degree from the
University of Göttingen
The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...
in March 1811.
Around that time, the two men engaged in an epistolary correspondence. However, when they met in person in 1825, they quarrelled; the details are not known.
In 1842 Bessel took part in the annual meeting of the
British Association for the Advancement of Science
The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Science (BA). The current Chi ...
in Manchester, accompanied by the geophysicist
Georg Adolf Erman
Georg Adolf Erman (12 May 1806 – 12 July 1877) was a German physicist.
Erman was born in Berlin as the son of Paul Erman. He studied natural science at the universities of Berlin and Königsberg, spent from 1828 to 1830 in a journey round ...
and the mathematician
Carl Gustav Jacob Jacobi.
Bessel married Johanna, the daughter of the chemist and pharmacist
Karl Gottfried Hagen who was the uncle of the physician and biologist
Hermann August Hagen and the hydraulic engineer
Gotthilf Hagen, the latter also Bessel's student and assistant from 1816 to 1818. The physicist
Franz Ernst Neumann
Franz Ernst Neumann (11 September 1798 – 23 May 1895) was a German mineralogist, physicist and mathematician.
Biography
Neumann was born in Joachimsthal, Margraviate of Brandenburg, near Berlin. In 1815 he interrupted his studies at Berlin ...
, Bessel's close companion and colleague, was married to Johanna Hagen's sister Florentine. Neumann introduced Bessel's exacting methods of measurement and data reduction into his mathematico-physical seminar, which he co-directed with
Carl Gustav Jacob Jacobi at Königsberg. These exacting methods had a lasting impact upon the work of Neumann's students and upon the Prussian conception of precision in measurement.
Bessel had two sons and three daughters. His elder son became an architect but died suddenly in 1840 aged 26; his younger son died shortly after birth. His eldest daughter, Marie, married the physicist
Georg Adolf Erman
Georg Adolf Erman (12 May 1806 – 12 July 1877) was a German physicist.
Erman was born in Berlin as the son of Paul Erman. He studied natural science at the universities of Berlin and Königsberg, spent from 1828 to 1830 in a journey round ...
, member of the scholar family
Erman Erman Rašiti may refer to:
Given name
* Erman Bulucu (born 1989), Turkish footballer
* Erman Eltemur (born 1993), Turkish karateka
* Erman Güraçar (born 1974), Turkish footballer
* Erman Kılıç (born 1983), Turkish footballer
* Erman Kunter (b ...
. One of their sons in turn was the renowned
Egyptologist Adolf Erman. His third daughter Johanna married the politician
Adolf Hermann Hagen
Adolf Hermann Wilhelm Hagen (23 September 1820 – 17 August 1894) was a public official in Prussia. He was also a banker and a liberal politician.
He is known for the "Hagen resolution", presented in the Prussian House of Representatives in ...
, their son was the physicist
Ernst Bessel Hagen.
After several months of illness Bessel died in March 1846 at his observatory from
retroperitoneal fibrosis.
Work
While the observatory was still in construction Bessel elaborated the ''Fundamenta Astronomiae'' based on Bradley's observations. As a preliminary result he produced tables of
atmospheric refraction that won him the
Lalande Prize from the
French Academy of Sciences
The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at ...
in 1811. The Königsberg Observatory began operation in 1813.
Starting in 1819, Bessel determined the position of over 50,000 stars using a
meridian circle from
Reichenbach, assisted by some of his qualified students. The most prominent of them was
Friedrich Wilhelm Argelander.
With this work done, Bessel was able to achieve the feat for which he is best remembered today: he is credited with being the first to use the
stellar parallax
Stellar parallax is the apparent shift of position of any nearby star (or other object) against the background of distant objects, and a basis for determining (through trigonometry) the distance of the object. Created by the different orbital p ...
in
calculating the distance to a star. Astronomers had believed for some time that parallax would provide the first accurate measurement of interstellar distances. In 1838 Bessel announced that
61 Cygni had a parallax of 0.314
arcsecond
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...
s; which, given the diameter of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
's orbit, indicated that the star is 10.3
ly away. Given the current measurement of 11.4 ly, Bessel's figure had an error of 9.6%.
Thanks to these results astronomers had not only enlarged the vision of the universe well beyond the cosmic magnitude, but after the discovery in 1728 by
James Bradley of the
aberration of light a second empirical evidence of the Earth's relative movement was produced.
Nearly at the same time
Friedrich Georg Wilhelm Struve and
Thomas Henderson measured the parallaxes of
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, a ...
and
Alpha Centauri
Alpha Centauri ( Latinized from α Centauri and often abbreviated Alpha Cen or α Cen) is a triple star system in the constellation of Centaurus. It consists of 3 stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centa ...
.
As well as helping determine the parallax of 61 Cygni, Bessel's precise measurements using a new meridian circle from Adolf Repsold allowed him to notice deviations in the motions of
Sirius
Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CM ...
and
Procyon, which he deduced must be caused by the gravitational attraction of unseen companions.
His announcement of Sirius's "dark companion" in 1844 was the first correct claim of a previously unobserved companion by positional measurement, and eventually led to the discovery of
Sirius B
Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CMa ...
.
Bessel was the first scientist who realized the effect later called ''
personal equation'', that several simultaneously observing persons determine slightly different values, especially recording the transition time of stars.
In 1824, Bessel developed a new method for calculating the circumstances of eclipses using the so-called
Besselian elements. His method simplified the calculation to such an extent, without sacrificing accuracy, that it is still in use today.
Bessel's work in 1840 contributed to the
discovery of Neptune
The planet Neptune was mathematically predicted before it was directly observed. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet were made on the night of September 23–24, 1846, at the ...
in 1846 at
Berlin Observatory, several months after Bessel's death. On Bessel's proposal (1825) the
Prussian Academy of Sciences started the edition of the ''Berliner Akademische Sternkarten'' (''Berlin Academic Star Charts'') as an international project. One unpublished new chart enabled
Johann Gottfried Galle
Johann Gottfried Galle (9 June 1812 – 10 July 1910) was a German astronomer from Radis, Germany, at the Berlin Observatory who, on 23 September 1846, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the pl ...
to find Neptune near the position calculated by LeVerrier in 1846.
In the second decade of the 19th century while studying the dynamics of 'many-body' gravitational systems, Bessel developed what are now known as
Bessel function
Bessel functions, first defined by the mathematician Daniel Bernoulli and then generalized by Friedrich Bessel, are canonical solutions of Bessel's differential equation
x^2 \frac + x \frac + \left(x^2 - \alpha^2 \right)y = 0
for an arbitrar ...
s. Critical for the solution of certain
differential equations, these functions are used throughout both classical and
quantum physics.
Bessel is responsible for the correction to the formula for the
sample variance
In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its population mean or sample mean. Variance is a measure of dispersion, meaning it is a measure of how far a set of numbe ...
estimator named in his honour. This is the use of the factor ''n'' − 1 in the denominator of the formula, rather than just ''n''. This occurs when the ''sample mean'' rather than the ''population mean'' is used to centre the data and since the sample mean is a linear combination of the data the residual to the sample mean overcounts the number of degrees of freedom by the number of constraint equations — in this case one. ''(Also see
Bessel's correction)''.
An additional field of work was
geodesy
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equival ...
.
Bessel published a method for solving the main
geodesic problem.
He was responsible for the survey of East Prussia which joined the Prussian and Russian
triangulation networks.
He also obtained an estimate of increased accuracy for the
Earth's ellipsoid
An Earth ellipsoid or Earth spheroid is a mathematical figure approximating the Earth's form, used as a reference frame for computations in geodesy, astronomy, and the geosciences. Various different ellipsoids have been used as approximations ...
, nowadays called the
Bessel ellipsoid
The Bessel ellipsoid (or Bessel 1841) is an important reference ellipsoid of geodesy. It is currently used by several countries for their national geodetic surveys, but will be replaced in the next decades by modern ellipsoids of satellite geode ...
, based on several
arc measurements.
Honors and prizes
* Honorary doctor degree from the
University of Göttingen
The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...
in March 1811
* Member of the
Prussian Academy of Sciences in 1812
* Member of the
French Academy of Sciences
The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at ...
in 1816
* Foreign member of the
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for prom ...
in 1823
* 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 1825
* 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, a ...
in 1832
* Member of the Royal Institute of the Netherlands, predecessor of the
Royal Netherlands Academy of Arts and Sciences
The Royal Netherlands Academy of Arts and Sciences ( nl, Koninklijke Nederlandse Akademie van Wetenschappen, abbreviated: KNAW) is an organization dedicated to the advancement of science and literature in the Netherlands. The academy is housed ...
in 1827
* 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 1840
* Bessel won the
Gold Medal of the Royal Astronomical Society twice, in 1829 and 1841.
The largest
crater
Crater may refer to:
Landforms
* Impact crater, a depression caused by two celestial bodies impacting each other, such as a meteorite hitting a planet
* Explosion crater, a hole formed in the ground produced by an explosion near or below the surf ...
in the Moon's
Mare Serenitatis and the
main-belt asteroid
1552 Bessel, as well as two fjords in Greenland,
Bessel Fjord, NE Greenland and
Bessel Fjord, NW Greenland, were named in his honour.
Publications
;Latin
*
*
;German
*
*
*
*
*
*
*
*
*
*
** Vol. 1: ''I. Bewegungen der Körper im Sonnensystem. II. Sphärische Astronomie''. Leipzig 1875
** Vol. 2: ''III. Theorie der Instrumente. IV. Stellarastronomie. V. Mathematik''. Leipzig 1876
** Vol. 3: ''VI. Geodäsie. VII. Physik. VIII. Verschiedenes – Literatur''. Leipzig 1876.
*
;Correspondence
* Königlich Preußische Akademie der Wissenschaften, ed. (1880)
''Briefwechsel zwischen Gauss und Bessel.'' orrespondenceLeipzig.
See also
*
Carlos Ibáñez e Ibáñez de Ibero
Carlos Ibáñez e Ibáñez de Ibero, 1st Marquis of Mulhacén, (14 April 1825 – 28 or 29 January 1891) was a Spanish divisional general and geodesist. He represented Spain at the 1875 Conference of the Metre Convention and was the first presid ...
– 1st president of the
International Committee for Weights and Measures and president of the
International Geodetic Association
References
*
John Frederick William 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 ...
, ''A brief notice of the life, researches, and discoveries of Friedrich Wilhelm Bessel'', London: Barclay, 1847
on-line
*
*
Jürgen Hamel: Friedrich Wilhelm Bessel. Leipzig 1984 .
* Kasimir Ławrynowicz: Friedrich Wilhelm Bessel, 1784–1846. Basel, Boston, Berlin 1995, .
*
*
*
Publications of Friedrich Wilhelm Bessel Astrophysics Data System ADS
Further reading
*
External links
*
*
*
{{DEFAULTSORT:Bessel, Friedrich Wilhelm
1784 births
1846 deaths
19th-century German mathematicians
Fellows of the American Academy of Arts and Sciences
Foreign Members of the Royal Society
19th-century German astronomers
German geodesists
Honorary members of the Saint Petersburg Academy of Sciences
Members of the French Academy of Sciences
Members of the Royal Netherlands Academy of Arts and Sciences
People from Minden
People from East Prussia
People from the Kingdom of Prussia
Recipients of the Gold Medal of the Royal Astronomical Society
Recipients of the Lalande Prize
Recipients of the Pour le Mérite (civil class)
Members of the Göttingen Academy of Sciences and Humanities