Jean-Philippe Loys de Cheseaux (; 4 May 1718 – 30 November 1751) was a

Swiss Swiss most commonly refers to: * the adjectival form of Switzerland * Swiss people Swiss may also refer to: Places * Swiss, Missouri * Swiss, North Carolina * Swiss, West Virginia * Swiss, Wisconsin Other uses * Swiss Café, an old café located ...

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

Biography

Loys de Cheseaux was born on 4 May 1718 in

Lausanne Lausanne ( , ; ; ) is the capital and largest List of towns in Switzerland, city of the Swiss French-speaking Cantons of Switzerland, canton of Vaud, in Switzerland. It is a hilly city situated on the shores of Lake Geneva, about halfway bet ...

Vaud Vaud ( ; , ), more formally Canton of Vaud, is one of the Cantons of Switzerland, 26 cantons forming the Switzerland, Swiss Confederation. It is composed of Subdivisions of the canton of Vaud, ten districts; its capital city is Lausanne. Its coat ...

, to Paul-Etienne Loys de Cheseaux, a

banneret A knight banneret, sometimes known simply as banneret, was a Middle Ages, medieval knight who led a company of troops during time of war under his own banner (which was square-shaped, in contrast to the tapering Heraldic flag#Standard, standar ...

, and Estienne-Judith de Crousaz. His brother was Charles-Louis Loys de Cheseaux. He was educated by his maternal grandfather, the mathematician and philosopher

Jean-Pierre de Crousaz Jean-Pierre de Crousaz (13 April 166322 March 1750) was a Swiss theologian and philosopher. He is now remembered more for his letters of commentary than his formal works. Life De Crousaz was born in Lausanne, Switzerland. He was a many-sided man, ...

, and wrote his first essays, under the title ''Essais de Physique'', in 1735, aged 17. In 1736, Loys de Cheseaux installed an observatory in his father's lands in

Cheseaux-sur-Lausanne Cheseaux-sur-Lausanne (, literally ''Cheseaux on Lausanne''; ) is a municipality in the district of Lausanne in the canton of Vaud in Switzerland. It is a suburb of the city of Lausanne. History Cheseaux-sur-Lausanne is first mentioned in 1228 ...

. He acquired a reputation in Europe as an astronomer with the publication of his ''Traité de la Comète'', in 1744, a treatise on his observations of the comet

C/1743 X1 The Great Comet of 1744, whose official designation is C/1743 X1, and which is also known as Comet de Chéseaux or Comet Klinkenberg-Chéseaux, was a spectacular comet that was observed during 1743 and 1744. It was discovered independently in lat ...

in which he also became one of the first to state, in its modern form, what would later be known as

Olbers' paradox file:Olbers' Paradox - All Points.gif, As more distant stars are revealed in this animation depicting an infinite, homogeneous, and static universe, they fill the gaps between closer stars. Olbers's paradox says that because the night sky is d ...

(that, if the

universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...

is infinite, the night sky should be bright). After his discovery of C/1743 (along with

Dirk Klinkenberg Dirk Klinkenberg (15 November 1709, Haarlem – 3 March 1799, The Hague) was secretary of the Dutch government for 40 years. He was also known as a mathematician and amateur astronomer. Jan de Munck, Dirk Klinkenberg, and Jean-Philippe de Chese ...

), Loys de Cheseaux discovered the comet C/1746 P1. In 1746, he presented a list of

nebula A nebula (; 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 regions, such as in the Pillars of Creation in ...

e, eight of which were his own new discoveries, to the

French Academy of Sciences The French Academy of 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 method, scientific research. It was at the forefron ...

. The list was noted privately by

Le Gentil Guillaume Joseph Hyacinthe Jean-Baptiste Le Gentil de la Galaisière (, 11 or 12 September 1725 – 22 October 1792) was a French astronomer who discovered several nebulae and was appointed to the Royal Academy of Sciences. He wrote on the est ...

in 1759, but only made public in 1892 by

Guillaume Bigourdan Camille Guillaume Bigourdan (; 6 April 1851 – 28 February 1932) was a French astronomer. Personal life Bigourdan was born at Sistels, Tarn-et-Garonne to Pierre Bigourdan and Jeanne Carrière. When his teachers and local curate recognised ...

. From 1747, Loys de Cheseaux was a

corresponding member The corresponding member is one of the possible membership types in some organizations, especially in the learned societies and scientific academies. This title existed or exist in the Soviet Union, GDR, Polish People's Republic, Czechoslovak S ...

of the science academies of

Göttingen Göttingen (, ; ; ) is a college town, university city in Lower Saxony, central Germany, the Capital (political), capital of Göttingen (district), the eponymous district. The River Leine runs through it. According to the 2022 German census, t ...

Saint Petersburg Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

and

Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...

, as well as the

and 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 ...

of London. He was offered the post of director of the St. Petersburg observatory, but declined the invitation. In 1751, Loys de Cheseaux travalled to Paris and was presented to the Academy of Sciences. There he died, after a short illness, on 30 November 1751, aged 33. In addition to astronomy, Loys de Cheseaux researched

Biblical chronology The chronology of the Bible is an elaborate system of lifespans, "generations", and other means by which the Masoretic Hebrew Bible (the text of the Bible most commonly in use today) measures the passage of events from the creation to around 164 ...

, calculating the movements of the Sun and Moon relative to descriptions in the

Book of Daniel The Book of Daniel is a 2nd-century BC biblical apocalypse with a 6th-century BC setting. It is ostensibly a narrative detailing the experiences and Prophecy, prophetic visions of Daniel, a Jewish Babylonian captivity, exile in Babylon ...

and the occurrence of

solstices A solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around 20–22 June and 20–22 December. In many countries, the s ...

and

equinoxes A solar equinox is a moment in time when the Sun appears directly above the equator, rather than to its north or south. On the day of the equinox, the Sun appears to rise directly east and set directly west. This occurs twice each year, arou ...

Jerusalem Jerusalem is a city in the Southern Levant, on a plateau in the Judaean Mountains between the Mediterranean Sea, Mediterranean and the Dead Sea. It is one of the List of oldest continuously inhabited cities, oldest cities in the world, and ...

at the time of the

Old Testament The Old Testament (OT) is the first division of the Christian biblical canon, which is based primarily upon the 24 books of the Hebrew Bible, or Tanakh, a collection of ancient religious Hebrew and occasionally Aramaic writings by the Isr ...

story. In his ''Dissertation Chronologique'' (1748), Loys de Cheseaux tried to establish the date of the

eclipse An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ...

known as "

crucifixion darkness The crucifixion darkness is an event described in the synoptic gospels in which the sky becomes dark in daytime during the crucifixion of Jesus for roughly three hours. Most ancient and medieval Christian writers treated this as a miracle, and b ...

" in order to determine the date of the

crucifixion of Jesus The crucifixion of Jesus was the death of Jesus by being crucifixion, nailed to a cross.The instrument of Jesus' crucifixion, instrument of crucifixion is taken to be an upright wooden beam to which was added a transverse wooden beam, thus f ...

References

Works

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External links

Short biography
at

SEDS Students for the Exploration and Development of Space (SEDS) is a non-profit international student organization whose purpose is to drive space advocacy of space exploration and development through educational and engineering projects. Hist ...

De Cheseaux's List of 21 "Nebulae"
at SEDS 1718 births 1751 deaths Scientists from Lausanne 18th-century Swiss astronomers Swiss nobility Discoverers of comets Swiss biblical scholars {{Europe-astronomer-stub