Johann Heinrich von Mädler

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Johann Heinrich von Mädler, lithograph by Rudolf Hoffmann , 1856
Signature Johann Heinrich von Mädler.PNG

Johann Heinrich Mädler , von Mädler since 1865 , (born May 29, 1794 in Berlin , † March 14, 1874 near Hanover ) was a German astronomer .

Among other things, von Mädler produced detailed maps of the moon , which had been the standard work of lunar research for decades, calculated the tropical year precisely , proposed a new switching rule for the calendar in 1864 and had already coined the term photography in 1839 .

life and work

Mädler was born the son of a Berlin master tailor. When he was born, however, he was so weak that it was feared that he would only survive a few hours. Over the years his constitution improved. His intellectual talents were noticed early on. From 1806 he attended the Berlin Friedrichwerder high school .

In 1813, both parents died of typhus within six weeks and the 19-year-old Johann Mädler had to take on the upbringing of his three younger sisters, who were 14, 11 and 5 years old.

He had always wanted to study mathematics and astronomy . Due to the loss of his parents, this was initially not possible. For the next five years, Mädler supported himself and his sisters by giving private lessons . Until 1817 he trained as a primary school teacher at a teacher training college. After that he gave private lessons and gave lectures at the teachers' college.

From 1818 onwards he studied mathematics under Martin Ohm and astronomy under Johann Elert Bode and Johann Franz Encke at the newly established University of Berlin .

In 1831, Mädler began teaching at the royal teachers' college in Berlin under Adolph Diesterweg . He dealt mainly with mathematics, science and handwriting . He published a textbook and didactic aids on writing skills.

From 1822 he began with meteorological observations, which he also published. In 1833 he carried out exact time determinations at Cape Arkona , the northernmost point of the island of Rügen , on behalf of the Prussian government. These were needed for a Russian " chronometric expedition".

In 1824 he had made the acquaintance of Wilhelm Beer , a wealthy Berlin banker interested in astronomy and brother of the composer Giacomo Meyerbeer . Beer was instructed by Mädler in astronomy and higher mathematics. In 1829 he had a private observatory near his villa built that with a very good achromatic lens with 9.5 cm opening and 1.5 m focal length of Joseph von Fraunhofer was appointed. In the next few years, Mädler and Beer carried out observations of the moon and the planets in particular .

In 1830 both observed Mars , made the first precise maps of the planet and determined its period of rotation . The determined value deviates from the value determined with today's means by only 13 seconds. Mädler and Beer also established the prime meridian of Mars.

Between 1830 and 1836, Mädler made drawings of the lunar surface for 600 nights. A large map of the moon with four sheets was created. The first sheet appeared in 1834; the lithographs were made by his cousin, Lieutenant Vogel. Together with a text work General Selenography , the maps were published in two volumes in 1837. Beer bore the costs for this. In 1838 a smaller moon map with a diameter of 33 cm was published. The maps subsequently became a standard work . Mädler became world famous and received numerous awards. He received a doctorate and was by Friedrich Wilhelm III. appointed professor of astronomy in December 1837 .

Through his work on the earth's moon, Mädler also got to know his future wife. Court councilor Wilhelmine Witte (November 17, 1777 to September 17, 1854) from Hanover , who was also very interested in astronomy, made a moon globe based on her own observations and Mädler's drawings. When she found out that he was in Pyrmont in the autumn of 1839 , she traveled there accompanied by her eldest daughter Minna von Witte (1804-1891) to ask him for his opinion. Mädler was not only taken with the moon globe, but also with the poet Minna, who had been taught astronomy by her mother. The two married in June 1840 and lived together for over 35 years. The moon globe was later praised by Alexander von Humboldt and John Herschel .

From 1836, Mädler worked as an observer at the newly established Berlin observatory , the director of which was his former professor Johann Franz Encke. Here he made observations with a telescope with an aperture of 24 cm .

In 1840 he went to the Dorpat observatory (today Tartu in Estonia ) as the successor to Friedrich Georg Wilhelm Struve , who had been appointed to the new Russian Central Observatory Pulkova . The largest refractor manufactured by Fraunhofer was located here. He had actually planned to make an even larger map of the moon. However, this failed due to the relatively small number of clear nights and he limited himself to detailed drawings.

In addition, Mädler Struves continued to observe binary stars and determined the proper motions of fixed stars. From his observations he derived the existence of a massive celestial body that should be located 5 billion miles away in the direction of the Pleiades . The stars would circle around this center of gravity , our sun would need 25 million years for one orbit  . Today we know that the center of our Milky Way galaxy is in the direction of Sagittarius and is about 28,000  light years away. Our solar system takes about 250 million years to orbit.

During his time in Dorpat, Mädler undertook two expeditions on behalf of the Russian government to observe total solar eclipses . The first, in Brest-Litowsk ( Poland ) in 1860 , could not be observed due to bad weather. The second, in Vitoria ( Spain ) in 1861 , was successful.

In addition, Mädler calculated the tropical year very precisely. On the basis of his results, he proposed to the Russian Empire , which still used the Julian calendar and thus the conventional tropical year of Sosigenes from Alexandria of exactly 365 days 6 hours, to make up the 12-day lag compared to the Gregorian calendar in 1900 , after that, however, an astronomically correct 128-year rule for the "exceptional common years" must be observed (see Mädler calendar ). The proposal was not accepted, however, and after the Bolshevik Revolution the Gregorian calendar was introduced instead, whose conventional tropical year of exactly 365.2425 days (365 days, 5 hours, 49 minutes, 12 seconds) dates back to Christophorus Clavius . In astronomy today, the conventional tropical year is mostly used according to Simon Newcomb with 365.2422 days (365d. 5H 48min. 46.08s). The actual tropical year measured in 2000.0 was 365.242190517 days, or about 365T. 5H 48min. 45.26s. This comes very close to the conventional tropical year according to Mädler: 365.2421875 days (exactly 365D. 5H 48Min. 45s). Since the length of the actual tropical year is currently slowly decreasing, currently by about half a second per century, the girlish and actual tropical year will be the same in a few decades, after which the difference will increase again.

Madler was an avid publicist throughout his academic career. He discussed scientific questions of the day in public papers and magazines in a generally understandable manner. In a report on a presentation by the photography pioneer William Henry Fox Talbot , he went far beyond the Talbot communiqués and was the first to coined the term photography in the Vossische Zeitung on February 25, 1839 (before English or French publications) . He was a member of the Society of German Natural Scientists and Doctors . Since 1845 he was a corresponding member of the Bavarian Academy of Sciences . In 1860 he was elected a member of the Leopoldina .

In 1865, Mädler retired, was raised to the Russian nobility and returned to Germany. Increasing eye problems had made my own observations impossible. In Wiesbaden he underwent a successful eye operation. From then on he devoted himself to his work History of Celestial Science , which appeared in 1873. He moved from Wiesbaden to Bonn , where he lived for three years. During this time he traveled to England , where he visited, among other things, the Royal Greenwich Observatory . At the request of his wife's family, the couple moved to Hanover. Madler died here at the age of 79 after a six-month illness.

In his memory, the asteroid (65859) Madler and a crater on the moon - the lunar crater, Mädler  - and Mars are named after him.


  • Textbook of calligraphy . Berlin 1827, 1840²
  • The Miraculous Building of Space, or Popular Astronomy. Berlin: 1841 (8th edition 1865), still continued today by Littrow et al. a.
  • Popular astronomy. Berlin: Carl Heymann, 2 1846. 4 1852. 5 1861.
  • Observations from the Dorpat observatory . Vol. 9-16. Dorpat: 1842-1866
  • The central sun . Dorpat: 1846
  • Investigations into the fixed star systems . 2 vols. Mitau: 1847–1848
  • Contributions to fixed star customers . Haarlem: 1855
  • The proper motions of the fixed stars . Dorpat: 1856
  • The fixed star sky . Leipzig: 1858
  • Speeches and treatises on celestial objects . Berlin: 1870
  • History of astronomy . 1. Vol. Braunschweig: 1872–1873
  • History of astronomy . 2. Vol. Braunschweig: 1872–1873


Web links

Commons : Johann Heinrich von Mädler  - Collection of images, videos and audio files
Wikisource: Johann Heinrich von Mädler  - Sources and full texts

Individual evidence

  1. Erich Stenger : The origin of the word "photography". In: der free lichtbildner (official organ of the Arbeiter-Lichtbild-Bund), Vol. 2, No. 2, February 15, 1933, pp. 14f
  2. Members of the Society of German Natural Scientists and Doctors 1857
  3. ^ Member entry by Johann Heinrich von Mädler at the German Academy of Natural Scientists Leopoldina , accessed on September 2, 2016.