A Unique Research and Educational Facility Near Boston, Massachusetts


Clay Center Observatory
The Clay Center Observatory is operated by Dexter Southfield, a private PK-12 educational institution. The facility includes a unique diffraction-limited 64cm (25-inch) telescope with optically perfect mirrors- better than 1/100th of a wave at 632.8nm.  Superb image quality is maintained by active thermal control in the dome. Multiple negative-pressure fans built into two airlocks cycle 10,000 cubic feet of air per minute through the dome, which keeps the interior temperature to within a fraction of a degree of the ambient air outside. Heat generated from the building is ducted underground to a facility 100 meters downwind, where it is exhausted- keeping thermal distortions near the telescope to a minimum.

Located atop the five-story Clay Center for Science & Technology, the observatory is housed in a 24.5-foot-diameter Ash Dome. Computerized and powered by its own solar-cell panels, the dome rotates in sync with the telescope and can be opened, closed, or rotated remotely by computer control. The north roof deck on Level 5 features a 5-kilowatt array of photovoltaic solar cells and a 1-kilowatt wind turbine, which provide supplemental energy for the facility. A rooftop weather tower delivers real-time atmospheric data. The south roof deck can support smaller telescopes for viewing along the ecliptic.

The pier for the telescope passes vertically through the Clay Center to its own foundation, without any contact with the building itself. This allows the telescope to be isolated from all building vibrations and ensures rock-steady imaging of stars, planets, galaxies, and satellites.

Clay Center for Science & TechnologyClay Center for Science & Technology
Visitors at the main entrance of the Clay Center are welcomed by the Sun Court, a scale-model of the planets and orbits of the inner solar system. Each planet in the display is represented by a round medallion indicating that planet’s distance from the Sun, its orbital period, and diameter. Each medallion also demonstrates the planet’s diameter compared to that of the Sun, which are represented by a small centered pin and the medallion’s outer diameter, respectively.

Nearby is the Moon Court. A visitor seated on the “Earth” (a bench in the middle) can observe major lunar phases from Full Moon to New Moon on surrounding brass globes. This courtyard is a popular spot for astronomy classes, picnic lunches, impromptu classes, and social gatherings.

The Stars Court illustrates classical constellation figures of the northern sky. The figures are rendered to duplicate the famous constellation drawings in Johann Bayer’s Uranometria, published in 1603. At night visitors can walk atop the figures’ illuminated stars etched into the courtyard pavers. Each star is a brilliant fiber-optic light pipe embedded in the precise location it appears in the nighttime sky.

Adjacent to the Stars Court is an Armillary Sphere based on the classical design used by Ptolemy in the second century A.D. Earth sits at its center, and interlocking, graduated rings represent the locations and paths of objects in the skies. Both artistic and historic, the armillary is used for teaching about early astronomers’ views of planetary motion.

Clay Center’s Space Science Laboratory

In the building lobby, beneath the pier’s two-story-tall base, is the Terrazzo Stars display, which accurately depicts the stars and constellations visible over Brookline at several times of the year.

In 2009, the Clay Center opened its Space Science Laboratory, designed not only to meet the needs of the schools’ growing upper-level student body but also to provide a spacious, well-equipped area for assembly and testing of research instrumentation. The Space Science Laboratory is located on the building’s 4th floor, just a few steps from the observatory’s telescopes and control center.

© 2014 Clay Center Observatory at Dexter Southfield