Wilhelm Beer was a Berlin banker and brother of the composer Meyerbeer, who set up a private observatory equipped with a 9.5-cm refractor. In collaboration with Johann H. Mädler, he produced, in 1830, the first accurate map of the Moon (Mappa Selenographica) and a companion descriptive volume (Der Mond), describing the surface features. These showed the Moon to be a world very unlike the Earth and contradicted the pro-selenite claims of Gruithuisen and William Herschel. Beer and Mädler's map remained the best available for several decades and helped persuade most professional astronomers that the Moon is uninhabited. The two also collaborated in the production of the first systematic chart of the surface of Mars.