Friedrich Georg Wilhelm Struve (15 April 1793 Altona – 23 November 1864 Pulkovo) Director in 1820-1839

Friedrich Georg Wilhelm Struve (15.04.1793 Altona – 23.11.1864 Pulkovo) Direktor 1820−1839 Wilhelm Struve was born in Altona belonging to Denmark (at present the suburb of Hamburg). His father Jacob Struve (1755-1841) was a professor of the local high school (later Rector). His mother Maria Emerentia (1764-1847) was a daughter of the local pastor. In 1808 Wilhelm had to flee from the town to avoid conscription to the Napoleon’s army. In Tartu his elder brother Karl was a private asssistant professor and Jacob Struve’s friend Heinrich Christian Schumacher worked as a private home tutor.

Taking his father’s will into consideration, Wilhelm began to study philology at Tartu University but he also registered himself to the courses of philosophy and astronomy. As his life was hard without the material support from parents, he began to work as a private home tutor of the children of the family Meiners and the sons of Count von Berg. His summers he spent in the Sangaste manor belonging to Count von Berg. During the war of 1812 he was arrested by the patrol as a French spy when he tried the Troughton sextant. The case was decided only in the military court in Pärnu.

Already at the end of 1810 Struve passed the candidate’s examination in philology and was awarded with the golden medal for a critical treatment of the works of Alexandrian poets. After graduating from the university, he was offered a post in the high school of Tartu but Struve refused because he wanted to continue his studies of mathematics and physics. Supported by a special grant given to him by Rector Parrot, Wilhelm began to study primarily astronomy and in October 1813 he simultaneously defended both his Master’s and Doctoral theses devoted to the determination of geographical coordinates of the Tartu observatory (De geographicae positione speculae Dorpatensis). Being only twenty years old, Struve became the astronomer-observer at the Tartu observatory and professor extraordinary of mathematics and astronomy. In 1820 the position of the observer was changed into ordinary professorship of astronomy which also included the responsibilities of official leadership of the observatory.

After having been nominated professor extraordinary, Wilhelm went back home in Altona to visit his parents whom he had not seen for six years. Being at home, he met Emilie Wall whom he married during his next visit to Altona at the beginning of June 1815. In October the same year he came back Tartu together with Emilie. During the marriage twelve children were born, four of them died in childhood.

In the spring of 1814 Struve began to deliver courses of lectures on practical geometry or land surveying, mathematical geography, trigonometry and astronomy. Despite intensive astronomical observations and frequent participation in geodetic field work, he did not interrupt lecturing for a single term. All in all during 25 years he delivered 20 lecture courses at Tartu University, on average six times each subject. Under the guidance of Struve, a number of outstanding scientists occupying key position in astronomy in Russia were prepared.

In the summers of 1815 and 1816 Struve travelled in Germany getting acquainted with leading astronomers and mathematicians (H. W. M. Olbers, C. F. Gauss, F. W. Bessel and others) and builders of observation instruments (J. G. Repsold, J. Fraunhofer). The result of the trip was that in 1817 the meridian circle was ordered from the Reichenbach and Ertel workshop in Munich.

In 1814 Struve started investigating binary stars. Although it was already known that many stars were binary or multiple, the relative coordinates of their components, their changes, also relative brightness and other features were not measured much. Since 1818 the attempts of measuring the distance of stars, the so-called observations of the parallactical shift, were added. Having carried out observations with the passage instrument, Struve came to the conclusion that parallactical shifts were smaller in general than the threshold of accuracy of the observation instruments in fundamental astronomy. This work helped deny the statements of some astronomers who erroneously thought that they had discovered parallactical shifts from the measurements of absolute coordinates.

In 1816-1819, ordered by the Livonian Generally Useful and Economic Society, under the guidance of Struve the astronomical and trigonometric measurements were carried out for preparing a new more exact map of Livonia. Inspired by the success of the work, in 1918 Struve offered a project to the university council to measure the 3 degree 35 minute meridian arc from the island of Högland in the Gulf of Finland to Jacobstadt (Jēkabpils) in Courland. The Emperor Alexander I also gave monetary support for buying the necessary instruments for measurement. Then followed the grand project of measuring the degree from Nordkap to the estuary of the River Danube in the range of 25 degree 20 minute which lasted until 1855 and ended when Wilhelm was already the director of the Pulkovo Observatory. The results of measuring the meridian arc in the years 1816-1855 Struve published in his book Arc du meridien in 1860.

Very soon Struve became a distinguished specialist in the field of higher geodesy and Tartu University became the most important centre for preparing astronomers and geodesists in Russia. Struve’s lectures were also attended by the students of the Professors` Institute and the officers of the General Headquarters and the Navy. In 1822 Struve was elected Corresponding Member of the Academy of Sciences of St. Petersburg. He planned and supervised the events of the Academy of Sciences, the General Headquarters, the Russian Geographical Society, etc, like continuing the measurements of the meridian arc in Finland, the astronomical tasks of geographical expeditions on land and the sea and the chronometric expeditions.

On 10 November 1924 the Fraunhofer refractor arrived in Tartu from Munich. But on 15 November Struve had assembled the refractor and on the following morning he started with the first test observations. After his first observation Wilhelm wrote in the journal Astronomishe Nachrichten: “Enchanted, I stood in front of a wonderful piece of art without being able to decide what was more surprising whether the instrument’s beautiful shape, or its perfectness in all the details or its reasonable structure and the most talented mechanism revolving the instrument, or its incomparable light power and the sharpness of the image.”

The Fraunhofer Refractor with micrometers allowed Struve to compile the catalogues of binary stars (observations in 1825-1827 published in the book Catalogus Novus Stellarum Duplicium et Multiplicium, 1827), also to measure reliably, for the first time in the world, the distance of the star (measurements in 1835-1836 are published in the book Mensurae micrometricae, 1837).

Struve became a famous astronomer known all over Europe. For the research of binary stars Struve was awarded with the golden medal of the Royal Astronomical Society in London which was highly appreciated by astronomers and the Czar of Russia Nikolai I presented Wilhelm with a diamond ring. Also, he was elected Honorary Member of the Academy of Sciences of St. Petersburg.

In 1834 the eldest son in the family Alfred died, in February Wilhelm’s wife Emilie died. In February 1835 Struve married again the mathematics professor Martin Bartels’s daughter Johanna. From this marriage six children were born, four of them reached adulthood.

In 1832 Struve was elected an acting member of the Academy of Sciences of St. Petersburg. Ordered by the Czar Nikolai I, he was appointed to the post of the director of the imperial Pulkovo Observatory under construction. He was also holding the post of the director of the Tartu Observatory until the Pulkovo Observatory was completed in 1839. From 13 April 1839 he was the director of the Pulkovo Observatory. In Pulkovo Wilhelm had to devote himself more and more to office work, active observation was the task of his subordinates. On his initiative the Pulkovo star catalogues began to appear exceeding all the other observatory catalogues thanks to their accuracy.

In 1847 the revolutionary work Etudes d´astronomie stellaire was published. In it Struve as the first astronomer proved the presence of the matter absorbing light in the interstellar space. On the basis of the list of stars he found that “the intensity of light decreases more than inversely proportional with the squares of distances which means that the loss of light exists when light goes through the interstellar space.” Saying that, Struve was at least 80 years ahead of his time because only in 1930 when Robert Julius Trumpler proved for the second time that light is absorbed in the interstellar space. This fact was recognized all over the world.

The summary of the work done in 1816-1855 in measuring the meridian arc remained the last book of the great scientist. At the beginning of 1858 he fell ill. The loss of memory did not allow him to do mental work. In the autumn of 1861 F. G. W. Struve left Pulkovo, freeing the post of the director of the Pulkovo Observatory and began to live together with his family in St. Petersburg where he lived until his death. In August 1864 Struve was participating in the celebrations devoted to the 25th anniversary of the opening of the Pulkovo Observatory. In the same year, on 23 November he died of lung inflammation. Struve was buried in the cemetery of the Pulkovo Observatory.

The famous astronomer’s name has been given to two mountains in the islands of Spitzbergen and to a mountain in the Queen Maud’s land in Antarctica.