Johann Heinrich von Mädler (29 May 1794,

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

– 14 March 1874,

Hannover Hanover ( ; ; ) is the capital and largest city of the States of Germany, German state of Lower Saxony. Its population of 535,932 (2021) makes it the List of cities in Germany by population, 13th-largest city in Germany as well as the fourth-l ...

) was a German

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

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 exposu ...

, 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, 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 developed diffraction grating and also invented the ...

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

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

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 arbitrarily chosen meridian (geography), meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. On a spheroid, a prime meridian and its anti-meridian (the 180th meridian ...

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

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

, which was off by almost 13 seconds. A later determination in 1837 was off by only 1.1 seconds. They also produced the first exact map of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

, ''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 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, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

(then

Russian Empire The Russian Empire was an empire that spanned most of northern Eurasia from its establishment in November 1721 until the proclamation of the Russian Republic in September 1917. At its height in the late 19th century, it covered about , roughl ...

), succeeding Friedrich Wilhelm Struve who had moved to

Pulkovo Observatory The Pulkovo Astronomical Observatory (), officially named the Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, is the principal astronomical observatory of the Russian Academy of Sciences. It is located 19 km south ...

. He carried out

meteorological Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agriculture ...

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 ...

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 changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

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 Seven Sisters and Messier 45 (M45), is an Asterism (astronomy), asterism of an open cluster, open star cluster containing young Stellar classification#Class B, B-type stars in the northwest of the constellation Tau ...

star cluster A star cluster is a group of stars held together by self-gravitation. Two main types of star clusters can be distinguished: globular clusters, tight groups of ten thousand to millions of old stars which are gravitationally bound; and open cluster ...

and that the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

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 went into effect in October 1582 following the papal bull issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian cale ...

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