German banker and amateur astronomer who (with Johann Heinrich von Mädler) constructed the most complete map of the Moon of his time, Mappa Selenographica (1836). The first lunar map to be divided into quadrants, it contained a detailed representation of the Moon's face and was accompanied, in 1837, by a volume providing micrometric measurements of the diameters of 148 craters and the elevations of 830 mountains.

The Mappa Selenographica remained unsurpassed until 1878, when J.F. Julius Schmidt's more detailed map appeared. Beer and Mädler also published (1830) a description and map of Mars that was the first to depict the light and dark areas.