Anders Celsius

Anders Celsius
Olof Arenius · Public domain · source
Name	Anders Celsius
Caption	Portrait of Anders Celsius
Birth date	27 November 1701
Birth place	Uppsala
Death date	25 April 1744
Death place	Uppsala
Nationality	Swedish
Fields	Astronomy, Physics, Meteorology
Institutions	Uppsala University, Royal Society
Alma mater	Uppsala University
Known for	Celsius temperature scale, geodesy, astronomy

Anders Celsius was an 18th-century Swedish astronomer and physicist noted for proposing a temperature scale that evolved into the modern Celsius scale. He served as professor at Uppsala University and directed the university observatory during a period of expanding European scientific collaboration involving institutions such as the Royal Society and the French Academy of Sciences. His work combined observational astronomy, geodesy, and instrument design, and he participated in international efforts to measure the shape of the Earth.

Early life and education

Celsius was born into an academically prominent family in Uppsala in 1701, the son of the astronomer Nils Celsius and nephew of the botanist Olof Celsius. He was educated at Uppsala University, where he studied under professors affiliated with the Swedish scientific network connected to the Royal Swedish Academy of Sciences. During his student years Celsius became acquainted with contemporary European scientists and their instruments, including influences from work published by astronomers at the Royal Observatory, Greenwich, the Paris Observatory, and scholars associated with the University of Leiden. His formative training combined classical university instruction at Uppsala University with practical observational practice on telescopes and barometers akin to those used by researchers at the University of Göttingen and the Academy of Sciences in Saint Petersburg.

Scientific career and astronomical work

After completing his studies Celsius was appointed to a position at Uppsala University and, in 1730, became professor of astronomy. He oversaw the construction and operation of the new observatory at Uppsala, equipping it with instruments comparable to those used at the Royal Observatory, Greenwich and the Paris Observatory. Celsius carried out systematic observations of comets, planetary occultations, and stellar positions, contributing data relevant to ephemerides compiled by astronomers such as Edmond Halley and Giovanni Cassini. He corresponded with leading figures including Joseph-Nicolas Delisle, James Bradley, and Leonhard Euler, exchanging observations and technical advice.

Celsius also led campaigns in geodetic measurement tied to the question debated by proponents like Isaac Newton and critics like Christiaan Huygens regarding the oblateness of the Earth. He organized arcs of measurement in northern latitudes, collaborating with surveyors and mathematicians in a manner similar to the Franco-Swedish expeditions that involved members of the French Academy of Sciences. The resulting data contributed to the broader 18th-century effort exemplified by the equatorial and polar expeditions led by scientists such as Pierre Bouguer and Alexis Clairaut.

Invention and development of the Celsius temperature scale

In 1742 Celsius published a proposal for a centigrade temperature scale initially defined with 0 degrees at the boiling point of water and 100 degrees at the freezing point, an inversion of the modern convention. He described the scale in the context of improved thermometer design and standardized calibration for meteorological and astronomical use, echoing instrument standardization efforts by makers associated with George Graham and Daniel Gabriel Fahrenheit. Celsius’s notation aimed to provide a decimal division between the fixed points of water, facilitating temperature comparison among observers across observatories like Uppsala Observatory, the Royal Observatory, Greenwich, and the Paris Observatory.

Following Celsius’s death, the inverted orientation was reversed by other scientists and instrument makers, including proponents working in France and Germany, to place 0 as the freezing point and 100 as the boiling point; this adjusted form spread via networks that involved instrument makers and scientific societies such as the Royal Society and the Royal Swedish Academy of Sciences. The adoption of the centigrade scale in continental scientific practice was accelerated by translations and publications by figures familiar with work from the University of Göttingen and the University of Edinburgh. Over the 19th and 20th centuries, the scale became codified internationally and is now defined through thermodynamic temperature relations treated by institutions such as the International Bureau of Weights and Measures.

Other scientific contributions and memberships

Beyond the temperature scale, Celsius contributed to meteorology through systematic temperature series and barometric observations at Uppsala Observatory, joining contemporaries who maintained long-term climate records like Daniel Fahrenheit and Edme Mariotte. He designed and commissioned instruments, working with instrument makers comparable to John Smeaton and continental craftsmen, to enhance precision in observations relevant to astronomy and surveying. Celsius was an active member of the scientific community, participating in the Royal Swedish Academy of Sciences activities and corresponding with members of the Royal Society and the French Academy of Sciences. His publications addressed instrument calibration, celestial observations, and geodetic methodology, placing him within a European network of scholars including Pierre-Louis Moreau de Maupertuis and Leonhard Euler who pursued Newtonian and cartographic questions.

Personal life and legacy

Celsius remained based in Uppsala for most of his career, maintaining scholarly ties across Sweden and continental Europe. He died in 1744, leaving manuscripts and instruments that influenced successors at Uppsala University and instrument makers in Stockholm and abroad. His name became eponymous with the centigrade scale as modified by colleagues and later standardized internationally, and his observational records contributed to the developing fields of climatology and geodesy. Commemorations include naming in scientific histories and institutional references within organizations such as the Royal Swedish Academy of Sciences and archival holdings at Uppsala University. Category:Swedish astronomers