Thomas Clausen (16 January 1801, Snogbæk, Sottrup Municipality,

Duchy of Schleswig The Duchy of Schleswig ( da, Hertugdømmet Slesvig; german: Herzogtum Schleswig; nds, Hartogdom Sleswig; frr, Härtochduum Slaswik) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km ( ...

(now

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...

) – 23 May 1885,

Dorpat Tartu is the second largest city in Estonia after the Northern Europe, Northern Europe, European country's political and financial capital, Tallinn. Tartu has a population of 91,407 (as of 2021). It is southeast of Tallinn and 245 kilometres ...

Imperial Russia The Russian Empire was an empire and the final period of the List of Russian monarchs, Russian monarchy from 1721 to 1917, ruling across large parts of Eurasia. It succeeded the Tsardom of Russia following the Treaty of Nystad, which ended th ...

(now

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

)) was a

Danish Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish a ...

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 ...

and

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 ...

. Clausen learned mathematics at home. In 1820, he became a trainee at the

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...

Optical Institute and in 1824, at the

Altona Observatory The Altona Observatory () was an astronomical observatory situated in the Palmaille, in Altona, Hamburg. The observatory was founded by Heinrich Christian Schumacher in 1823 and continued to operate until 1871, 21 years after his death. It close ...

after he showed

Heinrich Christian Schumacher Prof Heinrich Christian Schumacher FRS(For) FRSE (3 September 1780 – 28 December 1850) was a German- Danish astronomer and mathematician. Biography Schumacher was born at Bramstedt, in Holstein, near the German/Danish border. He was educ ...

his paper on calculating longitude by the

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

of stars by the moon. He eventually returned to Munich, where he conceived and published his best known works on mathematics. In 1842 Clausen was hired by the staff of the

Tartu Observatory The Tartu Observatory ( et, Tartu Observatoorium) is the largest astronomical observatory in Estonia. On 1 January 2018, Tartu Observatory was joined again to the University of Tartu, and the observatory is now an institute of the university. I ...

, becoming its director in 1866-1872. Works by Clausen include studies on the stability of

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

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 ...

movement, ABC

telegraph code A telegraph code is one of the character encodings used to transmit information by telegraphy. Morse code is the best-known such code. ''Telegraphy'' usually refers to the electrical telegraph, but telegraph systems using the optical telegraph w ...

and calculation of 250 decimals of pi (later, only 248 were confirmed to be correct). In 1840 he discovered the Von Staudt–Clausen theorem. Also in 1840 he also found two compass and straightedge constructions of

lune Lune may refer to: Rivers *River Lune, in Lancashire and Cumbria, England *River Lune, Durham, in County Durham, England *Lune (Weser), a 43 km-long tributary of the Weser in Germany *Lune River (Tasmania), in south-eastern Tasmania, Australia Pl ...

s with equal area to a square, adding to three (including the

lune of Hippocrates In geometry, the lune of Hippocrates, named after Hippocrates of Chios, is a lune (mathematics), lune bounded by Circular arc, arcs of two circles, the smaller of which has as its diameter a Chord (geometry), chord spanning a right angle on the l ...

) known to the ancient Greek mathematician

Hippocrates of Chios Hippocrates of Chios ( grc-gre, Ἱπποκράτης ὁ Χῖος; c. 470 – c. 410 BC) was an ancient Greek mathematician, geometer, and astronomer. He was born on the isle of Chios, where he was originally a merchant. After some misadve ...

; it was later shown that these five lunes are the only possible solutions to this problem.. Translated from Postnikov's 1963 Russian book on

Galois theory In mathematics, Galois theory, originally introduced by Évariste Galois, provides a connection between field theory and group theory. This connection, the fundamental theorem of Galois theory, allows reducing certain problems in field theory to ...

. In 1854 he factored the sixth

Fermat number In mathematics, a Fermat number, named after Pierre de Fermat, who first studied them, is a positive integer of the form :F_ = 2^ + 1, where ''n'' is a non-negative integer. The first few Fermat numbers are: : 3, 5, 17, 257, 65537, 4294967 ...

as 2⁶⁴+1 = 67280421310721 × 274177.

Notes

References

* * * {{DEFAULTSORT:Clausen, Thomas 1801 births 1885 deaths 19th-century Danish mathematicians 19th-century Danish astronomers

See also

Notes

References