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Virtual Tours of the Great Refractor, Plate Stacks Now Available

The public can now "walk-through" two popular facilities at the Center for Astrophysics.

The Center for Astrophysics | Harvard & Smithsonian now offers virtual tours of two popular facilities on campus: the Great Refractor and the Plate Stacks. Both tours allow visitors to walk through the facilities from the comfort of their own homes while learning about the history and purpose of each space.

The Great Refractor

This historic telescope on the rooftop of the Center for Astrophysics was built in 1847 and was the largest telescope in the United States for 20 years. Fundraisers for the first-class telescope include David Sears, John Quincy Adams and Joseph Peabody.

The Great Refractor was active for nearly three-quarters of a century. During the first 30 years, the work was chiefly determination of stellar positions and visual observation of planets, variable stars, comets and nebulae. After the appointment in 1877 of the observatory's fourth director, Edward C. Pickering, the telescope was employed almost entirely for photometry, or the measurement of light.

For the past 50 years, the Great Refractor has been used only for an occasional student or special research project, but still stands as an incredible example of 19th century scientific, engineering and architectural achievements.

Walk through and explore the Great Refractor below:


The Plate Stacks

The Astronomical Photographic Plate Collection, also known as the Plate Stacks, is the largest archive of celestial glass plates in the world. These historical images of the sky are preserved on glass photographic plates, the way professional astronomers often captured images before the advent of digital technology.

The Plate Stacks collection spans nearly a century of images taken from 1885-1992 and includes over 500,000 images covering both the northern and southern hemispheres. The photos include a wide range of astronomical subjects, such as Hailey’s Comet, galaxies, eclipses, the Horsehead Nebula and Pluto.

Since the early 2000s, researchers with the DASCH (Digital Access to a Sky Century @ Harvard) project have actively scanned the plates for digital storage and analysis. Digitization of the data and images can be used by contemporary astronomers to understand how objects in the night sky change over periods of years to decades.

Click below to explore the Plate Stacks: