'100-inch Reflecting Telescope, Mount Wilson Solar Observatory', c 1917.
© Science Museum / Science & Society Picture Library
Drawing of a cross-section of the Hooker Telescope showing the construction of the instrument mounting. With a glass mirror 100 inches in diameter, the Hooker Telescope was the largest instrument of its kind when it was completed in 1917. The brainchild of American astronomer George Ellery Hale (1868-1938), it is located at a height 5,000 feet overlooking the city of Los Angeles in the United States. Although light pollution from the encroaching city has degraded the once dark skies, the telescope is still in use today. Using adaptive optics, which removes the blurring effects of the atmosphere, the telescope can now see much finer detail. These modifications have extended the working life of this venerable telescope, so that it is still at the vanguard of astronomical research.