Yale–Columbia Southern Observatory

The Yale–Columbia Southern Observatory, established in 1925 in Johannesburg, South Africa, is a significant astronomical facility that played a crucial role in determining the distances of southern stars. Founded by Yale University and later in collaboration with Columbia University, the observatory utilized a 26-inch refractor telescope to conduct extensive observations. Its strategic location aimed to minimize light pollution, enhancing the quality of astronomical research. The observatory completed its primary mission in 1951 but was eventually closed due to urban light pollution. Today, visitors can explore the nearby Wits planetarium, while the historic refractor now resides at Mount Stromlo Observatory.