ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY
At right is the secondary mirror, used to reflect light from the larger primary mirror towards the camera (left) that contains photographic plates. This 30-inch telescope was erected at the Helwan Observatory, Cairo, Egypt. It was provided in 1905 by British astronomer John Henry Reynolds (1874-1949). The first large telescope erected in Africa and the Middle East, it began operations in January 1909, observing Halley's Comet that year. It was used to observe galaxies, providing data for modern galaxy classification. It was also used to observe comets, Jupiter's eighth satellite, Pluto, and solar eclipses.
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