Date of Birth: 06/22/1784
Place of birth: Minden
German astronomer and mathematician Friedrich Wilhelm Bessel (1784-1846) was born in the small town of Minden in the north-west of Germany, in the family of a petty official. His career began trading Bessel employees. Diligently engaged in self-education, he quickly and successfully mastered the knowledge of mathematics and astronomy. For 20-year-old boys Bessel independently calculated the orbit of Halley`s Comet. Becoming an assistant astronomer at large J. Schroeter, Bessel studied observations of the stars. This work soon earned him a reputation as a prominent astronomer observer and evaluator-math.
In 1810, Bessel was invited to Koenigsberg, where he became a professor of astronomy at the University of Konigsberg. Here, under his leadership, the observatory was built, the director of which he remained until his death.
Bessel - one of the founders of astrometry. He has consistently implemented the idea of ??the need to make amendments to the results of observations, taking into account the influence of the most seemingly insignificant factors, reducing the accuracy of astrometric measurements. Bessel has developed a rigorous mathematical correction methods rezultatovnablyudeny. The first major work of the Bessel in this direction was processing the results of observations of the stars of the provisions in the catalog compiled in the 40-50-ies of the 18th century the English astronomer John. By Bradley. Later he led Bessel observation positions of the stars. He defined the position of the stars and 75,000 created extensive star catalogs, which became the basis of current knowledge about the starry sky.
Bessel was one of the first astronomers to measure the parallax, and thus the distance to the stars. After Struve, who in 1837 first defined the distance to the star Vega in the constellation Lyra, Bessel in 1838, measured the distance to the star 61 Cygni. This star was one of the closest to the solar system.
Watching for a number of years, the bright stars Sirius and Procyon, Bessel found in their movement of such features, which can be explained only by the fact that these stars have satellites. But these satellites are so weak on the luminosity that they can not be seen through telescopes. Assumption Bessel subsequently confirmed: in 1862. detected companion star Sirius, and in 1896 - a satellite of Procyon.