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

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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 ...

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, 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, 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. 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 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), 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 in 1759, but only made public in 1892 by Guillaume Bigourdan. From 1747, Loys de Cheseaux was a corresponding member of the science academies of

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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 and equinoxes in

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" 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
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