Johann Heinrich von Mädler (29 May 1794,

Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...

– 14 March 1874,

Hannover Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German States of Germany, state of Lower Saxony. Its 535,932 (2021) inhabitants make it the List of cities in Germany by population, 13th-largest city in Germa ...

) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

Life and work

His father was a master tailor and when 12 he studied at the Friedrich‐Werdersche Gymnasium in Berlin. He was orphaned at age 19 by an outbreak of

typhus Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposure. ...

, and found himself responsible for raising three younger sisters. He began giving academic lessons as a private tutor and in this way met

Wilhelm Beer Wilhelm Wolff Beer (4 January 1797 – 27 March 1850) was a banker and astronomer from Berlin, Prussia, and the brother of Giacomo Meyerbeer. Astronomy Beer's fame derives from his hobby, astronomy. He built a private observatory with a ...

, a wealthy banker, in 1824. In 1829 Beer decided to set up a private observatory in Berlin, with a 95 mm

refractor telescope A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...

made by

Joseph von Fraunhofer Joseph Ritter von Fraunhofer (; ; 6 March 1787 – 7 June 1826) was a German physicist and optical lens manufacturer. He made optical glass, an achromatic telescope, and objective lenses. He also invented the spectroscope and developed diffract ...

, and Mädler worked there. In 1830 they began producing drawings of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

which later became the first true maps of that planet. They were the first to choose what is today known as Sinus Meridiani as the

prime meridian A prime meridian is an arbitrary meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian (the 180th meridian in a 360°-system) form a great c ...

for Martian maps. They made a preliminary determination for Mars's

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

, which was off by almost 13 seconds. A later determination in 1837 was off by only 1.1 seconds. Mädler-2

They also produced the first exact map of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

, ''Mappa Selenographica'', published in four volumes in 1834–1836. In 1837 a description of the Moon (''Der Mond'') was published. Both were the best descriptions of the Moon for many decades, not superseded until the map of

Johann Friedrich Julius Schmidt Johann Friedrich Julius Schmidt (25 October 1825 in Eutin, Germany – 7 February 1884 in Athens, Greece) was a German astronomer and geophysicist. He was the director of the National Observatory of Athens in Greece from 1858 to 1884. Julius Schmi ...

in the 1870s. Beer and Mädler drew the firm conclusion that the features on the Moon do not change, and there is no atmosphere or water. In 1836,

Johann Franz Encke Johann Franz Encke (; 23 September 179126 August 1865) was a German astronomer. Among his activities, he worked on the calculation of the periods of comets and asteroids, measured the distance from the Earth to the Sun, and made observations ...

appointed Mädler an observer at the

Berlin Observatory The Berlin Observatory (Berliner Sternwarte) is a German astronomical institution with a series of observatories and related organizations in and around the city of Berlin in Germany, starting from the 18th century. It has its origins in 1700 w ...

, and he observed with its 240-mm refractor. In 1840, Mädler was appointed director of the Dorpat (Tartu) Observatory in

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

(then

Russian Empire The Russian Empire was an empire and the final period of the Russian monarchy from 1721 to 1917, ruling across large parts of Eurasia. It succeeded the Tsardom of Russia following the Treaty of Nystad, which ended the Great Northern War. ...

), succeeding Friedrich Wilhelm Struve who had moved to

Pulkovo Observatory The Pulkovo Astronomical Observatory (russian: Пулковская астрономическая обсерватория, Pulkovskaya astronomicheskaya observatoriya), officially named the Central Astronomical Observatory of the Russian Academ ...

. He carried out

meteorological Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...

as well as astronomical observations. He continued Struve's observations of

double star In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a bi ...

s. He remained in Tartu until he retired in 1865, and then returned to Germany. By examining the

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

s of stars, he came up with his "Central Sun Hypothesis", according to which the center of the galaxy was located in the

Pleiades The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance of ...

star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clust ...

and that the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

revolves around it. He got the location wrong. He published many scientific works, among them a two-volume ''History of Descriptive Astronomy'' in 1873. Mädlers ''Populäre Astronomie – Wunderbau des Weltalls'' ("Popular Astronomy – the Miraculous Architecture of the Universe") reached out to wider audiences; an eighth edition was published in 1885. In 1864, he proposed a calendar reform for Russia: After dropping 12 days to align with

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years dif ...

dates before the year 1900, the leap year in 1900 along with every 128th year afterwards (2028, 2156, etc.) under the Julian rules would be cancelled. This would give a mean year of 365 days, 5 hours, 48 minutes, 45 seconds, which is extremely close to the mean tropical year. Neither the Tsar nor Orthodox clergy accepted this unsolicited proposal, though a modified version of it was made by Sergey Glazenap in 1900, and ultimately Russia would adopt the Gregorian calendar in 1918. The craters Mädler on the Moon and Mädler on Mars are both named in his honor.

References

Bibliography

* Heino Eelsalu, Dieter B. Herrmann: ''Johann Heinrich Mädler (1794–1874): Eine dokumentarische Biographie.'' Akademie-Verlag Berlin, 1985 ISSN 0138-4600 (German)

External links

* Frank J. Tipler
"Olbers's Paradox, the Beginning of Creation, and Johann Mädler,"
''Journal for the History of Astronomy'', Vol. 19, Pt. 1 (February 1988), pp. 45–48. *F. J. Tipler
"Johann Mädler's Resolution of Olbers' Paradox,"
''Quarterly Journal of the Royal Astronomical Society'', Vol. 29, No. 3 (September 1988), pp. 313–325. *Frank J. Tipler
"More on Olbers's Paradox,"
a review of Edward Harrison, ''Darkness at Night: A Riddle of the Universe'' (Cambridge, Mass.: Harvard University Press, 1987), ''Journal for the History of Astronomy'', Vol. 19, Pt. 4 (November 1988), pp. 284–286. (Note that the last page is missing in the PDF version of the article at the foregoing link, but is contained in the GIF version.) *http://www.uapress.arizona.edu/onlinebks/mars/chap04.htm *http://www.obs.ee/obs/maedler/maedler.html * *

Obituary

{{DEFAULTSORT:Madler, Johann Heinrich 1794 births 1874 deaths 19th-century German astronomers Selenographers Historians of astronomy Recipients of the Lalande Prize