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This 140-foot (43-meter) aluminum-clad parabolic dish antenna sits on the world’s largest polar-aligned mount in Green Bank, West Virginia. The rounded yoke swivels around the central axis of the telescope which is aligned perfectly with the rotational axes of the Earth. The dish can swivel up and down, giving it a contortionist’s amount of flexibility. In this way, the telescope can easily track objects in the sky as they appear to rise and set from the Earth’s spin on its axis.

This 140-foot aluminum-clad parabolic dish antenna was completed in spring of 1965 after many years of design and development. Even from miles away, this 200-foot tall giant was an impressive sight in Green Bank, West Virginia. In this rare photo, the 43-meter dish is aimed directly at the Pole Star. Look directly below the dish to the right to see that the polar shaft is aiming there as well. This telescope is the largest polar-aligned telescope in the world.

The 140-foot dish of this telescope in Green Bank, West Virginia is supported by a 266-ton aluminum dish superstructure (BUS). A huge yoke is attached to the tilting axis that runs through the BUS, allowing the enture dish to dip and lift on a 42-foot diameter gear. The yoke’s middle is anchored to a 67-foot long shaft that is parallel to the axis of the Earth. The yoke can then turn on its huge gear against the spinning of the Earth to let the 140-foot (43-meter) telescope track objects in the sky.

The original polar shaft of the 140-foot (43-meter) telescope in Green Bank, West Virginia was a welded steel unit delivered in 1959. A 22-foot wide welded steel bearing was meant to attach to the end to form the spin axis of the telescope; however, small cracks were discovered throughout the sphere. By 1962, and after many heated debates and re-evaluations, these welded steel designs were abandoned. The steel from the sphere was taken to Long Island to shield the particle accelerator at Brookhaven National Laboratory, and this shaft was installed as a culvert under one of the roads at our observatory.

This 140-foot aluminum-clad parabolic dish antenna sits on the world’s largest polar-aligned mount. The rounded yoke swivels around the central axis of the telescope which is aligned perfectly with the rotational axes of the Earth. In this way, the 43-meter dish can easily track objects in the sky as they appear to rise and set from the Earth’s spin on its axis. The small white tower to the left is rolled up to the telescope when the dish is lowered to the ground for engineers to work on the prime focus at the tips of the four support legs.

In December of 1964, the last of 60 aluminum surface panels was installed on the 140-foot (43-meter) telescope in Green Bank, West Virginia.