Johann Heinrich von Mädler

Johann Heinrich Mädler since 1865 by Mädler, (* May 29, 1794 in Berlin, † March 14, 1874 in Hannover ) was a German astronomer.

From Mädler made ​​to, among other detailed maps of the moon, which had for decades the standard work of lunar exploration, calculated precisely the tropical year, hit 1864 before a new switching rule for the calendar and had coined the term photography in the year 1839.

Life and work

Mädler was the son of a master tailor in Berlin to the world. At birth, however, he was so weak that it was feared he could survive only a few hours. Over the years, his physique improved. Early on, fell on his intellectual talents. From 1806 he attended the Berlin Friedrichwerdersche school.

1813 both parents died within six weeks of typhoid fever and the 19 -year-old Johann Mädler had to take over from now on the education of his three younger sisters, who were 14, 11 and 5 years old.

He had always had a desire to study mathematics and astronomy. Due to the loss of his parents, this was not possible for now. The next five years brought Mädler by himself and his sisters by giving private lessons. He was trained to 1817 at a teacher training college as an elementary school teacher. After that he gave private lessons and gave lectures at the teacher training college.

Alongside he studied from 1818 at the newly constructed University of Berlin under Martin Ohm mathematics and astronomy under Johann Elert Bode Johann Franz Encke and.

1831 Mädler took a teaching position at the royal teacher seminar in Berlin with Adolph Diesterweg on. It dealt mainly with mathematics, science and calligraphy customer. To calligraphy customer, he published a textbook and teaching aids.

From 1822 he began meteorological observations that he published. In 1833, he led the Cape Arkona, the northernmost point of the island of Rügen, on behalf of the Prussian government exact time provisions by. These were for a Russian " chronometric expedition " is required.

In 1824 he had made the acquaintance of William Berry, one interested in astronomy wealthy Berlin banker and brother of the composer Giacomo Meyerbeer. Beer was taught by Mädler in astronomy and higher mathematics. In 1829 he had a private observatory near his villa building, which was equipped with a very good achromat with 9.5 cm aperture and 1.5 m focal length by Joseph von Fraunhofer. Here Mädler and Beer led in the next few years in particular observations of the moon and the planets.

Both 1830 observed Mars, made ​​at first accurate maps of the planet and its specific rotation period. The measured value deviates only 13 seconds from the value given with today's means. Mädler and Beer also laid firmly the prime meridian of Mars.

Between 1830 and 1836 made ​​Mädler during 600 nights drawings of the lunar surface at. There was a large map of the moon with four leaves. The first paper appeared in 1834, the lithographs had created his cousin, Lieutenant bird. Together with a text Work General selenography the maps were published in 1837 in two volumes. The cost of this was Beer. 1838 appeared a smaller moon map with 33 cm diameter. The cards were in the period following the standard work. Mädler became world famous and has received numerous awards. He received a doctorate degree and was designed by Frederick William III. appointed in December 1837 Professor of Astronomy.

His work on the earth's moon Mädler met his future wife. The councilor's wife Wilhelmine von Witte (November 17, 1777 to September 17, 1854 ) from Hannover, which was also very interested in astronomy, made ​​a moon globe on personal observations and Mädler drawings. When she learned that he stayed in Pyrmont in autumn 1839, she traveled in the company of her eldest daughter Minna von Witte ( 1804-1891 ) there to ask him for his opinion. Mädler was not only impressed by the moon globe, but also by the poet Minna, who had been taught by her mother in astronomy. 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 built Berlin Observatory, whose leader was his former professor Johann Franz Encke. Here he conducted observations with the telescope through a 24 cm opening width.

In 1840 he went as a successor of Friedrich Georg Wilhelm Struve, who had been appointed to the new Russian Central Observatory Pulkova, at the observatory of Dorpat ( now Tartu in Estonia). Here was the largest made ​​by Fraunhofer refractor. He had actually planned to create 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 Struve continued observations of double stars and determined the proper motions of the fixed stars. From his observations, he headed the presence of a massive celestial body, which would have to be in the direction of the Pleiades in five billion miles away. Around this center of gravity, the stars would orbit our sun would need for a round 25 million years. Today we know that the center of our Milky Way is in the direction of Sagittarius and about 28,000 light years away. Our solar system requires approximately 250 million years to revolve.

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

In addition Mädler calculated the tropical year very precise. Based on his results, he proposed to the Russian Empire, which still use the Julian calendar and thus the conventional tropical year of Sosigenes from Alexandria of exactly 365 days used 6 hours ago, in 1900, the residue of 12 days, catch up with the Gregorian calendar, but afterwards observed an astronomically correct 128- year sunset clause for the " 'exceptional common years " (see Mädler calendar). The proposal was not taken up, and after the Bolshevik Revolution, the Gregorian calendar was introduced instead, the conventional tropical year of 365.2425 days exactly (365 days, 5 hours, 49 minutes, 12 seconds) back to Christopher Clavius ​​. In astronomy, usually the conventional tropical year according to Simon Newcomb to 365.2422 days ( 365T. 5H 48min. 46.08 s ) used today. The actual measured in 2000.0 tropical year was 365.242190517 days, or about 365T. 5H 48min. 45,26 see This is the conventional tropical year according Mädler: 365.2421875 days (. . Exactly 365T 5H 48min 45s ) very close. Since the length of the actual tropical year decreases slowly at present, currently about half a second per century, Mädlerisches and actual tropical year will be in a few decades the same length, after which the difference will increase again.

Mädler was an avid writer throughout his scientific activity. He discussed scientific issues of the day in the public papers and magazines in common understandable way. In a report on a presentation of the photographic pioneer William Henry Fox Talbot, he went far beyond the Talbot releases and coined as the first (even before the English or French publications ) in the Vossische newspaper dated February 25, 1839 the concept of photography.

1865 Mädler retired, was elevated into the Russian nobility, and returned to Germany. Increasing eye problems had made his own observations impossible. In Wiesbaden, he underwent a successful eye surgery. He devoted himself to his work history of astronomy, which appeared in 1873. From Wiesbaden, he moved to Bonn, where he lived for three years. During this time he traveled to England, where he attended the Royal Greenwich Observatory among others. At the request of his wife's family, the couple moved to Hanover. Here Mädler died at the age of 79 after six months of illness.

Moon crater Mädler - - In his memory, each a crater on the Moon and Mars are named after him.