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Bessel was the son of a civil servant, and at the age of 14 he was apprenticed to the import-export concern Kulenkamp . He shortly became an accountant for them, and the business' reliance on cargo ships led him to turn his mathematical skills to problems in navigation. This in turn led to an interest in astronomy as a way of determining longitudeMap of Earth showing vertical lines of longitude Longitude sometimes denoted λ, describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. Longitude is given as an angular measurement ranging from 0° at.
He came to the attention of a major figure of German astronomy at the time, Heinrich Wilhelm Olbers, by producing a refinement on the orbital calculations for Halley's Comet. Within two years he had left Kulenkamp and become an assistant at Lilienthal Observatory near Bremen, Germany. There he worked on James Bradleysee Jim Bradley for the Ontario Member of Provincial Parliament James Bradley ( 1693 July 13, 1762) was an English astronomer, Astronomer Royal from 1742. He was born at Sherborne, Gloucestershire in March 1693. He entered Balliol College, Oxford, on Marc's stellar observations to produce precise positions for some 3222 stars.
This work attracted considerable attention, and at the age of 26 he was appointed director of the Königsberg Observatory by Frederick William III of PrussiaFrederick William III known in German as Friedrich Wilhelm III reigned as king of Prussia from 1797 to 1840. The son of King Frederick William II of Prussia, Frederick William was born in Potsdam on August 3, 1770, and became Crown Prince in 1786, when hi. There he published tables of atmospheric refraction based on Bradley's observations, which won him the Lalande Prize from the Institut de FranceThe Institut de France (French Institute) is a French learned society, grouping five academies the most famous of which is probably the Academie francaise. The institute manages approximately one thousand foundations. It also awards prizes and subsidies,. On this base, he was able to pin down the position of over 50,000 stars during his time at Konigsberg.
With this work under his belt, Bessel was able to achieve the feat for which he is best remembered today: he is credited with being the first to use parallaxParallax is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. Or more simply put, it is the apparent shift of an object against a background due to a change in observ in calculating the distance to a star. Astronomers had believed for some time that parallax would provide the first accurate measurement of interstellar distances -- in fact, the 1830s housed a fierce competition between astronomers to be the first to accurately measure a stellar parallax. In 1838 Bessel won the "race", announcing that 61 Cygni had a parallax of 0.314 arcseconds; which, given the diameter of the Earth's orbit, indicated that the star was ~3 parsecs away. Hipparcos has calculated the parallax at 0.28547 arcseconds. He narrowly beat Friedrich Georg Wilhelm Struve and Thomas Henderson, who measured the parallaxes of Vega and Alpha Centauri in the same year.
As well as helping determine the parallax of 61 Cygni, Bessel's precise measurements allowed him to notice deviations in the motions of Sirius and Procyon, which he deduced must be caused by the gravitational attraction of unseen companions. His announcement of Sirius' "dark companion" in 1841 was the first correct claim of a previously unobserved companion by positional measurement, and eventually led to the discovery of Sirius B.
Despite lacking a university education, Bessel was a major figure in astronomy during his lifetime. He was elected a fellow of the Royal Society, and the largest crater in the moon's Mare Serenitatis was named after him.
He won the Gold Medal of the Royal Astronomical Society in 1841.
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