Friedrich Wilhelm Bessel (July 22, 1784 – March 17, 1846) was a German mathematician, astronomer, and systematizer of the Bessel functions (which, despite their name, were discovered by Daniel Bernoulli). He was born in Minden, Westphalia and died of cancer in Königsberg (now Kaliningrad, Russia). Bessel was a contemporary of Carl Gauss, also a mathematician and astronomer. July 22 is the 203rd day (204th in leap years) of the year in the Gregorian Calendar, with 162 days remaining. ... 1784 was a leap year starting on Thursday (see link for calendar). ... March 17 is the 76th day of the year in the Gregorian Calendar (77th in Leap years). ... 1846 was a common year starting on Thursday (see link for calendar). ... A mathematician is a person whose area of study and research is mathematics. ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... In mathematics, Bessel functions, first defined by the Swiss mathematician Daniel Bernoulli and named after Friedrich Bessel, are canonical solutions y(x) of Bessels differential equation: for an arbitrary real number α (the order). ... Daniel Bernoulli Daniel Bernoulli (Groningen, February 9, 1700 – Basel, March 17, 1782) was a Dutch-born mathematician who spent much of his life in Basel, Switzerland. ... Minden is a town in North Rhine-Westphalia, Germany. ... Westphalia (in German, Westfalen) is a (historic) region in Germany, centred on the cities of Dortmund, Münster, Bielefeld, and Osnabrück and now included in the Bundesland of North Rhine-Westphalia (and the (south-)west of Lower Saxony). ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Locator map on an international level map of Kaliningrad Oblast Kaliningrad ( Russian: Калининград, German: Königsberg, Polish: Królewiec, Lithuanian Karaliaučius ), seaport city, capital and main city of the Kaliningrad Oblast, a Russian exclave between Poland and Lithuania with access to the Baltic Sea. ... Johann Carl Friedrich Gauss Johann Carl Friedrich Gauss (Gauß) (April 30, 1777 – February 23, 1855) was a German mathematician and scientist who contributed significantly to many fields, including number theory, analysis, differential geometry, geodesy, magnetism, astronomy and optics. ...

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 longitude. Map of Earth showing curved 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. ...

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 Bradley's stellar observations to produce precise positions for some 3222 stars. Categories: Astronomers stubs | 1758 births | 1840 deaths | German astronomers | German physicists | Lists of asteroids ... Comet Halley as taken with the Halley Multicolor Camera on the ESA Giotto mission. ... Andor Lilienthal (b. ... For other uses, see Bremen (disambiguation). ... see Jim Bradley for the Ontario Member of Provincial Parliament James Bradley (1693 - July 13, 1762) was an English astronomer, Astronomer Royal from 1742. ...

This work attracted considerable attention, and at the age of 26 he was appointed director of the Königsberg Observatory by Frederick William III of Prussia. There he published tables of atmospheric refraction based on Bradley's observations, which won him the Lalande Prize from the Institut de France. On this base, he was able to pin down the position of over 50,000 stars during his time at Königsberg. ... Frederick William III Frederick William III, known in German as Friedrich Wilhelm III, reigned as king of Prussia from 1797 to 1840. ... The tendancy of light to diverge from a striaght path as it moves from one medium to another is refraction. ... The Institut de France (French Institute) is a French learned society, grouping five académies, the most famous of which is probably the Académie française. ...

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 parallax 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. Parallax (Greek: παραλλαγή (parallagé) = alteration) 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. ... A calculation is a deliberate process for transforming one or more inputs into one or more results. ... personal space, proxemics. ... The Pleiades star cluster A star is any massive gaseous body in outer space, just like the Sun. ... 1838 was a common year starting on Monday (see link for calendar). ... 61 Cygni is a star in the Cygnus constellation. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ... The parsec (symbol pc) is a unit of length used in astronomy. ... The High Precision Parallax Collecting Satellite of the Hipparcos Space Astrometry Mission was a project of the European Space Agency (ESA) dedicated to the measurement of stellar parallax and the proper motions of stars. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... Friedrich Georg Wilhelm von Struve Friedrich Georg Wilhelm von Struve (April 15, 1793 – November 23, 1864 (Julian calendar: November 11)) was a German-Russian astronomer. ... Thomas Henderson (December 28, 1798 – November 23, 1844) was an astronomer noted for being the first person to measure the distance to Alpha Centauri, the major component of the nearest stellar system to Earth, and for being the first Astronomer Royal of Scotland. ... Vega (α Lyr / α Lyrae / Alpha Lyrae) is the brightest star in the constellation Lyra, and the fifth brightest star in the sky. ... The position of Alpha Centauri Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and contains the fourth brightest star in the sky, with a total visual magnitude of −0. ...

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. This article is about the star. ... The position of Procyon Procyon (α CMi / α Canis Minoris / Alpha Canis Minoris) is the brightest star in the constellation Canis Minor and the eighth brightest star in the nighttime sky. ... 1841 is a common year starting on Friday (link will take you to calendar). ... This article is about the star. ...

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. The Royal Society of London for the Improvement of Natural Knowledge, known simply as the Royal Society, is claimed to be the oldest learned society still in existence. ... This article is about impact craters, also known as meteor craters. ... A map of Mare Serenitatis. ...

He won the Gold Medal of the Royal Astronomical Society in 1841. The asteroid 1552 Bessel was named in his honour. The Gold Medal is the highest award of the Royal Astronomical Society. ... 1841 is a common year starting on Friday (link will take you to calendar). ...

External links

• http://www-groups.dcs.st-andrews.ac.uk/~history/Mathematicians/Bessel.html