Johann Heinrich Mädler (29 May 1794 Berlin – 14 March 1874 Hannover) Director in 1840-1865

Mädler was born to the family of a tailor and he chose the career of a schoolteacher. He lost his parents when he was nineteen and had to start working to earn money to support his sisters and brothers. He established a private school for poor children, gave private lessons and then he worked as a teacher of calligraphy at the college for teachers headed by the famous educationalist F. A. W. Diesterweg.

He began to be interested in astronomy in 1811 when he saw a comet which could be well observed in the sky with a naked eye. From 1818 he began to attend lectures of astronomy at Berlin University. Private lessons took Mädler in 1824 to the banker Wilhelm Beer (1797-1850) who founded his private observatory in Berlin in Tiergarten. As a result of observations at 600 nights, Mädler and Beer published an extraordinarily exact and profound atlas of the Moon (“Mappa selenographica”, 1837) and the first complete map of the Mars.

In Tartu Mädler made different observations. First of all he continued to study the Moon and continued the measurements of the location of stars and binary stars started by Struve. Beside that he observed the planets, comets, noctilucent clouds, carried out regular weather observations and wrote articles which were published in the newspapers of Tartu and Riga, also in different science journals of Europe. In Tartu Mädler wrote an extensive “Popular astronomy” which came out in eight prints. He also compiled a book about the history of astronomy, published a textbook of cosmography and geography and worked at the principles of the calendar reform. Mädler’s bibliography contains 290 publications in total.

Mädler was interested in cosmology, i.e. the study of the universe as a whole. His book Centralsonne (1846), which contained hypotheses about the structure of the galaxy, caused a dispute of a long-time duration. His main book (Fixsternsysteme) is considered to be one of the corner stones of stellar dynamics. Mädler was the first who tried to join different catalogues of stars into a system and proposed that the stars move in the stellar systems on circular orbits. Both his right and wrong ideas have helped develop the theory of cosmology further.

Mädler was a member or a honorary member of 19 academies and learned societies. He was a doctor of Leipzig University and a honorary doctor of Vienna University. For the research of the Moon he was awarded with a medal of France, service award of Denmark and Prussia, a diamond ring from the Czar of Russia. In the history of astronomy Mädler’s name is recorded as the founder of stellar dynamics and scientific cosmology and the developer of selenography.

In 1996 the Mädler memorial plaque was fixed to the house belonging to the observatory ensemble. One crater of the Moon and one crater of the Mars bear Mädler’s name.