Johann Heinrich von Mädler

Who was Johann Heinrich von Mädler?

Johann Heinrich von Mädler was a German astronomer.

He was orphaned at age 19 by an outbreak of typhus, 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 made by Joseph von Fraunhofer, and Mädler worked there. In 1830 they began producing drawings of Mars 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 for Mars maps.

They made a preliminary determination for Mars' rotation period, 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, Mappa Selenographica, published in four volumes in 1834–1836. In 1837 a description of the Moon 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 Both were the best descriptions of the Moon for many decades, not superseded until the map of Johann Friedrich Julius Schmidt in the 1870s.