Relocation of the Berlin Observatory to Babelsberg

At the end of the 19th century, the Berlin Observatory, originally built outside the city, had become surrounded by blocks of flats, making scientific observation almost impossible. Therefore, Wilhelm Foerster proposed the relocation of the observatory to a place outside Berlin with better observational conditions. To realize this project, he appointed Karl Hermann Struve, former director of the observatory of Königsberg, as his successor in 1904.

After test observations made by Paul Guthnick in the summer of 1906, a new site was found on a hill in the eastern part of the Royal Park in Babelsberg. The crown placed the ground at the observatory's disposal free of charge. The costs of the new buildings and the new instruments amounted to 1.5 million Goldmark, which was covered by selling the landed property of the Berlin Observatory. The old observatory, built by Schinkel, was later pulled down. In June 1911 the construction of a new observatory began in Babelsberg and on August 2, 1913 the move from Berlin to Babelsberg was completed.

The first new instruments were delivered in the spring of 1914. The 65cm refractor, which was the first big astronomical instrument manufactured by the famous Carl Zeiss Jena company, was mounted in 1915. As a result of the First World War, the completion of the 120cm mirror telescope was delayed until 1924. When Struve died in an accident in 1920, he was succeeded by Paul Guthnick, who had introduced photoelectric photometry into astronomy as the first objective method of measuring the brightness of stars in 1913. With the completion of the 122cm telescope, which at that time was the second largest in the world, the Babelsberg Observatory became the best-equipped observatory in Europe.

The development of the photoelectric method for investigating weak variable stars and spectroscopic investigations with the 122cm telescope also made the Babelsberg observatory well known outside Europe.

At the start of 1931, the Sonneberg Observatory, founded by Cuno Hoffmeister, was linked to the Babelsberg Observatory. For more than sixty years it carried out a photographic sky survey, which is the world’s second largest archive of astronomical photographic plates. This archive, along with the discovery and investigation of variable stars, popularized Sonneberg throughout the astronomical world.

With the onset of the fascist regime, the fortunes of astronomy in Potsdam and Babelsberg began to decline. The banishment of Jewish workers played an essential role in this process. The outbreak of the Second World War resulted in almost complete cessation of astronomical research.