The Hooker Telescope Dome with shutter partly open, c 1917

The Hooker Telescope Dome with shutter partly open, c 1917. One of a series of 41 bromide prints showing the construction of the Hooker 100-inch reflector at Mount Wilson, California, United States. The observatory at Mount Wilson was founded in 1904 by the astronomer George Ellery Hale (1868-1938), with funding from the Carnegie Institution. The 100-inch reflecting telescope installed at the observatory in 1917 was the largest telescope in the world at the time, and remained so until the 200-inch reflector at Mount Palomar became operational in 1948. Mount Wilson was at the forefront of astronomy in the first half of the 20th century. Observations by astronomers working there confirmed that the Universe was expanding, as well as leading to substantial advances in understanding of the workings of the Sun. ©SSPL/Science Museum