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Ernst Friedrich Knorre

Ernst Friedrich Knorre
Ernst Friedrich Knorre.jpg
Born Ernst Christoph Friedrich Knorre
(1759-12-11)11 December 1759
Neuhaldensleben, German Empire
Died 1 December 1810(1810-12-01) (aged 50)
Dorpat, Russian Empire
Alma mater University of Halle
Organization
Known for Charting geography of Estonia
Children Karl Friedrich Knorre

Ernst Christoph Friedrich Knorre (11 December 1759 – 1 December 1810) was a German-born astronomer who lived and worked in present-day Estonia as a founding professor of mathematics at the Universität Dorpat and chief observator for the Dorpat Observatory. His son Karl Friedrich Knorre and grandson Viktor Knorre were also notable astronomers. Recently NASA named an asteroid in honor of the three generations of Knorre astronomers.

Knorre was born at Neuhaldensleben, near Magdeburg, in the German Empire. As a young man, he left home with his elder brother Johann to study theology at the University of Halle, where the two also secured positions as private tutors. In 1786, Johann was offered a position as the director of a new secondary school for girls in Dorpat and soon after, he left for the province of Livonia in present-day Estonia. Knorre joined him a short time later, and eventually took over as headmaster of the school in 1780 when Johann left Dorpat for Narva.

At the age of 35, Knorre, who always had a strong interest in science and mathematics, began to explore astronomy. At that time, the city of Dorpat had no university, and Knorre had little support in his scholastic pursuits, but he nevertheless undertook a daily record of his work, making regular entries about his celestial observations in his journal as early as 1795. That same year, he began to design and construct his own astronomical instrument, and set out to determine the geographical latitude of the city of Dorpat. With the help of little more than a plumb-line and bob, he fixed four plates with a series of round holes atop the wall of the two-story home where he lived. With a mirror placed under the lowest opening, Knorre observed the stars, seeking the one with a declination of between 58° and 59° to pass along the diameter of the uppermost opening. He recorded the star as Ursa Minor, though it is uncertain whether it was in fact that star. In spite of the primitive nature of his equipment, upon completing his calculations, Knorre became the first to determine the latitude of the observatory.


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