Christian Sørensen Longomontanus
Encyclopedia
Christen Sørensen Longomontanus (or Longberg) (4 October 1562 – 8 October 1647) was a Danish
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

.

The name Longomontanus was a Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

ized form of the name of the village of Lomborg, Jutland
Jutland
Jutland , historically also called Cimbria, is the name of the peninsula that juts out in Northern Europe toward the rest of Scandinavia, forming the mainland part of Denmark. It has the North Sea to its west, Kattegat and Skagerrak to its north, the Baltic Sea to its east, and the Danish–German...

, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

, where he was born. His father, a laborer called Søren, or Severin, died when he was eight years old. An uncle took charge of the child, and had him educated at Lemvig
Lemvig
Lemvig is a municipality in Region Midtjylland on the west coast of the Jutland peninsula in west Denmark. The municipality covers an area of 510 km², and has a population of 22,067 . Its mayor is Erik Flyvholm, a member of the Venstre political party.The main town and the site of its municipal...

; but after three years sent him back to his mother, who needed his help to work the fields. She agreed that he could study during the winter months with the clergyman of the parish; this arrangement continued until 1577, when the ill-will of some of his relatives and his own desire for knowledge caused him to run away to Viborg
Viborg, Denmark
Viborg , a town in central Jutland, Denmark, is the seat of both Viborg municipality and Region Midtjylland. Viborg is also the seat of the Western High Court, the High Court for the Jutland peninsula...

.

There he attended the grammar school
Grammar school
A grammar school is one of several different types of school in the history of education in the United Kingdom and some other English-speaking countries, originally a school teaching classical languages but more recently an academically-oriented secondary school.The original purpose of mediaeval...

, working as a labourer to pay his expenses, and in 1588 went to Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...

 with a high reputation for learning and ability. Engaged by Tycho Brahe
Tycho Brahe
Tycho Brahe , born Tyge Ottesen Brahe, was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations...

 in 1589 as his assistant in his great astronomical observatory of Uraniborg
Uraniborg
Uranienborg was a Danish astronomical observatory operated by Tycho Brahe; built circa 1576-1580 on Hven, an island in the Øresund between Zealand and Scania, which at that time was part of Denmark. The observatory was shortly after its construction expanded with an underground facility,...

, he rendered invaluable service for eight years. Having left the island of Hven
Hven
Ven is a small Swedish island in the Öresund strait, between Scania and Zealand . It is situated in Landskrona Municipality, Skåne County. The island has 371 inhabitants and an area of . During the 1930s, the population was at its peak, with approximately 1,300 inhabitants...

 with his master, he obtained his discharge at Copenhagen on 1 June 1597, in order to study at some German universities. He rejoined Tycho at Prague
Prague
Prague is the capital and largest city of the Czech Republic. Situated in the north-west of the country on the Vltava river, the city is home to about 1.3 million people, while its metropolitan area is estimated to have a population of over 2.3 million...

 in January 1600, and having completed the Tychonic lunar theory, turned homeward again in August.

He visited Frauenburg, where Copernicus
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....

 had made his observations, took a masters degree at Rostock
University of Rostock
The University of Rostock is the university of the city Rostock, in the German state of Mecklenburg-Vorpommern.Founded in 1419, it is the oldest and largest university in continental northern Europe and the Baltic Sea area...

, and at Copenhagen found a patron in Christian Friis, chancellor of Denmark, who employed him in his household. Appointed in 1603 rector of the school of Viborg, he was elected two years later to a professorship in the University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...

, and his promotion to the chair of mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

 ensued in 1607. This post he held till his death.

Longomontanus was not an advanced thinker. He adhered to Tycho's erroneous views about refraction
Refraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

, believed that comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...

s were messengers of evil, and imagined that he had squared the circle
Squaring the circle
Squaring the circle is a problem proposed by ancient geometers. It is the challenge of constructing a square with the same area as a given circle by using only a finite number of steps with compass and straightedge...

. He found that the circle whose diameter is 43 has for its circumference the square root of 18252 which gives 3.14185 ... for the value of π. John Pell
John Pell
-Early life:He was born at Southwick in Sussex. He was educated at Steyning Grammar School, and entered Trinity College, Cambridge, at the age of thirteen. During his university career he became an accomplished linguist, and even before he took his B.A. degree corresponded with Henry Briggs and...

 and others tried in vain to convince him of his error. He inaugurated, at Copenhagen in 1632, the erection of a stately astronomical tower
Rundetårn
The Rundetårn is a 17th-century tower located in central Copenhagen, Denmark. One of the many architectural projects of Christian IV, it was built as an astronomical observatory...

, but did not live to witness its completion. King Christian IV of Denmark
Christian IV of Denmark
Christian IV was the king of Denmark-Norway from 1588 until his death. With a reign of more than 59 years, he is the longest-reigning monarch of Denmark, and he is frequently remembered as one of the most popular, ambitious and proactive Danish kings, having initiated many reforms and projects...

, to whom he dedicated his Astronomia Danica, an exposition of the Tychonic system of the world, conferred upon him the canonry of Lunden in Schleswig
Schleswig
Schleswig or South Jutland is a region covering the area about 60 km north and 70 km south of the border between Germany and Denmark; the territory has been divided between the two countries since 1920, with Northern Schleswig in Denmark and Southern Schleswig in Germany...

.

However, it was Longomontanus who really developed Tycho's geoheliocentric model empirically and publicly to common acceptance in the 17th century in his 1622 astronomical tables. When Tycho died in 1601, his program for the restoration of astronomy was unfinished. The observational aspects were complete, but two important tasks remained, namely the selection and integration of the data into accounts of the motions of the planets, and the presentation of the results on the entire program in the form of a systematic treatise. Longomontanus, Tycho's sole disciple, assumed the responsibility and fulfilled both tasks in his voluminous Astronomia Danica (1622). Regarded as the testament of Tycho, the work was eagerly received in seventeenth-century astronomical literature. But unlike Tycho's, his geoheliocentric model gave the Earth a daily rotation as in the models of Ursus and Roslin, and which is sometimes called the 'semi-Tychonic' system. As an indication of his book's popularity and of the semi-Tychonic system, it was reprinted in 1640 and 1663. Having originally worked on calculating the Martian orbit for Tycho with Kepler, he had already modelled its orbit to within 2 arcminutes error in longitude in his geoheliocentric model when Kepler had still only achieved 8 arcminutes error in his heliocentric system. Some historians of science claim Kepler’s 1627 Rudolphine Tables based on Tycho Brahe’s observations were more accurate than any previous tables. But nobody has ever demonstrated they were more accurate than Longomontanus’s 1622 Danish Astronomy tables, also based upon Tycho’s observations.

Publications

His major works in mathematics and astronomy were:
  • Systemalis Mathematici, etc. (1611)
  • Cyclometria e Lunulis reciproce demonstrata, etc. (1612)
  • Disputatio de Eclipsibus (1616)
  • Astronomia Danica, etc. (1622)
  • Disputationes quatuor Astrologicae (1622)
  • Pentas Problematum Philosophae (1623)
  • De Chronoiabio Historico, seu de Tempore Dispulatsones tres (1627)
  • Geometriae quaesita XIII. de Cyclometria rabionali et vera (1631)
  • Inventio Quadraturae Circuli (1634)
  • Disputatio de Matheseos Indole (1636)
  • Coronis Problematica ex Mysteriis trium Numerorum (1637)
  • Problemata duo Goemetrica (1638)
  • Problema contra Paulum Guidinum de Circuli Mensura (1638)
  • Introductio in Theatrum Astronomicum (1639)
  • Rotundi in Piano, etc. (1644)
  • Admiranda Operatio trium Numerorum 6, 7, 8, etc. (1645)
  • Caput tertium Libri primi de absoluta Mensura Rotundi plani, etc. (1646)

External links

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