Johann Heinrich von Mädler | |
|---|---|
 Johann Heinrich von Mädler | |
| Born | (1794-05-29)29 May 1794 Berlin |
| Died | 14 March 1874(1874-03-14) (aged 79) |
| Scientific career | |
| Fields | astronomy |
Johann Heinrich von Mädler (29 May 1794,Berlin – 14 March 1874,Hannover) was a Germanastronomer.
His father was a master tailor and when 12 he studied at the Friedrich‐Werdersche Gymnasium in Berlin.[1] He was orphaned at age 19 by an outbreak oftyphus, and found himself responsible for raising three younger sisters. He began giving academic lessons as a private tutor and in this way metWilhelm Beer, a wealthy banker, in 1824.
In 1829 Wilhelm Beer decided to set up a private observatory in Berlin, with a 95 mmrefractor telescope made byJoseph von Fraunhofer, and Mädler worked there.
In 1830 Beer and Mädler began producing drawings ofMars which later became the first true maps of that planet. They were the first to choose what is today known asSinus Meridiani as theprime meridian for Martian maps.
They made a preliminary determination for Mars'srotation period, which was off by almost 13 seconds. A later determination in 1837 was off by only 1.1 seconds.
Beer and Mädler also produced the first exact map of theMoon,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 Both were the best descriptions of the Moon for many decades, not superseded until the map ofJohann Friedrich Julius Schmidt in the 1870s.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 appointed Mädler an observer at theBerlin Observatory, and he observed with its 240-mm refractor. In 1840, Mädler was appointed director of theDorpat (Tartu) Observatory inEstonia (thenRussian Empire), succeedingFriedrich Wilhelm Struve who had moved toPulkovo Observatory. He carried outmeteorological as well as astronomical observations. He continued Struve's observations ofdouble stars. He remained in Tartu until he retired in 1865, and then returned to Germany.
By examining theproper motions of stars, he came up with his "Central Sun Hypothesis", according to which the center of the galaxy was located in thePleiadesstar cluster and that theSun revolves around it. He got the location wrong.
He published many scientific works, among them a two-volumeHistory of Descriptive Astronomy in 1873. MädlersPopuläre Astronomie – Wunderbau des Weltalls ("Popular Astronomy – the Miraculous Architecture of the Universe") reached out to wider audiences; an eighth edition was published in 1885.[2]
In 1864, he proposed a calendar reform for Russia: After dropping 12 days to align withGregorian calendar 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.[3][4] Neither the Tsar nor Orthodox clergy accepted this unsolicited proposal, though a modified version of it was made bySergey Glazenap in 1900, and ultimately Russia would adopt the Gregorian calendar in 1918.
The cratersMädler on the Moon andMädler on Mars are both named in his honor.
