March 27: Mapping the Moon in the 1830s

Wilhelm Wolff Beer, a German banker and astronomer who built a private observatory in Berlin and produced (with his mentor, Johann Heinrich Mädler) the first exact map of the Moon between 1834-1836, died at 53 on this date in 1850. Beer also mapped the planet Mars in 1840 and accurately calculated its rotation period to within less than a second of accuracy. Beer’s Moon map remained the best available for several decades, and helped convince most astronomers that the Moon, despite contrary theories by other stargazers, was uninhabited. He also helped build Prussia’s first railway system, was an advocate on behalf of the German Jewish community, and was elected to the Prussian parliament the year before his death. Craters on both the Moon and Mars, as well as an asteroid, are named for Beer. Their moon map “was incomparably superior to anything of its kind previously attempted, being executed with the utmost care and representing years of laborious micrometric measurements. Each landmark discovered on the moon’s surface was noted with great precision, and 919 spots and 1,095 determinations of the heights of lunar mountains were measured by the two astronomers . . .” —Encyclopedia Judaica