Dom Pedro II Observatory, Saint Thomas Island, Danish Possession in the Antilles: Interior View of the East Pavillion with the Equatorial Telescope of the Lieutenant Commander Calheiros da Graça


This photograph is contained in an album that commemorates the participation of Brazil in the international effort to track the transit of Venus in 1882. This involved the establishment by the Imperial Observatory of an observatory, named after Emperor Dom Pedro II (1825-91), on the island of Saint Thomas in the Danish West Indies (present-day U.S. Virgin Islands). The transit of Venus is a rare astronomical event that occurs when Venus passes between the Earth and the sun, becoming visible in daylight against the solar disk. The transits occur in eight-year pairs at intervals of more than a century. Since the 17th century, astronomers had been especially interested in these transits, as they offered the chance, using multiple observations and complex mathematical calculations, to determine the distance between the Earth and the sun (the Astronomical Unit). There thus was great scientific as well as public interest in the transits of 1874 and 1882. The album is part of the Thereza Christina Maria Collection at the National Library of Brazil. Composed of 21,742 photos assembled by Emperor Pedro II throughout his life and donated by him to the national library, the collection covers a wide variety of subjects and documents the achievements of Brazil and Brazilians in the 19th century. The collection, named after Empress Thereza Christina Maria, was inscribed on the UNESCO Memory of the World register in 2003.

Last updated: July 1, 2014