The Lake County Astronomical Society

Astronomy Bio...Friedrich Wilhelm Bessel

Jay Bitterman

Wilhelm Bessel was born on July 22, 1784 in Minden, Westphalia (now Germany). His father, Carl Friedrich Bessel, was a government civil servant in Minden. His mother was Friederike Ernestine Bessel. He went to the Gymnasium in Minden for four years but was an unremarkable student with limited talent and found Latin to be difficult. In later years he taught himself and became proficient in Latin, which suggests that the Gymnasium failed to inspire Bessel. At the age of 14, in January 1799, he left school to work as an apprentice for the commercial import-export firm of Kulenkamp in Bremen. Initially the firm did not pay him but the firm so appreciated his accounting skills that he was given a small salary. Because the firm had dealings with exporting to England and Spain, Bessel spent his evenings studying geography, Spanish and English. Geography sparked his interest in navigation and the problem of finding the position of a ship at sea. In 1801 he took a course in navigation. Consequently he had to study astronomy and mathematics and so he began to make observations to determine longitude.

At the age of 20, in 1804, he calculated and wrote a paper on the orbit of Halley's Comet by utilizing Harriot's 1607 data and observations. His paper was passed on to the leading comet expert of the time, Heinrich Olbers. Olbers immediately recognized the quality of Bessel's work and gave him the mission of making further observations and to continue his work. Since his paper was at the level requisite for a doctoral dissertation, on Olbers' recommendation it was published. Now Bessel devoted more of his time to astronomy, celestial mechanics and mathematics.

Olbers suggested to Bessel, that although he was still an apprentice to the import-export firm, he should pursue astronomy as a profession. In 1806 he was offered and accepted the post of assistant at the private Lilienthal Observatory near Bremen. Reluctantly, after much thought, Bessel quit the affluence of his commercial job and chose instead the near poverty of the Observatory post.

In 1807 he started to work on reducing the English astronomer James Bradley's 1750 observations of the positions of 3222 stars that were made at Greenwich.

In 1809 Bessel was picked to be director of Frederick William III of Prussia's new Königsberg Observatory (construction completed in 1813) and professor of astronomy. He was awarded a doctorate by the University of Göttingen on the recommendation from Gauss, who had recognized Bessel's talents when they met in Bremen in 1807. In May 1810 he assumed his new post and continued his work on Bradley's observations. Bessel's work on Bradley's observations become known internationally and was awarded the Lalande Prize from the Institute de France for his tables of refraction. In 1812, Bessel married Johanna Hagen and had one son (Wilhelm) and three daughters (Marie, Elisabeth, and Johanna.) While at Königsberg, Bessel embarked on the colossal task of determining the positions and proper motions of over 50,000 stars that led to his 1838 discovery of the parallax of 61 Cygni.

In 1840 Bessel's health began to deteriorate and his last long trip, in 1842, was to England, where he participated in the Congress of the British Association in Manchester. He died on March 17, 1846 in Königsberg, Prussia.