TelescopesGriffith Observatory is one of the premier public observatories in the world. One of the principal reasons is the presence and regular availability of high-quality public telescopes. Griffith J. Griffith wanted the public to have the opportunity to look through a telescope, which he felt might broaden human perspective. Mounted in the copper-clad domes on either end of the building, the Zeiss and solar telescopes are free to the public every day and night the sky is clear.
Since opening in 1935, more than seven million people have put an eye to Griffith Observatory's original 12-inch Zeiss refracting telescope. More people have looked though it than any other telescope in the world. Located in the roof-top dome on the building's east end, the Zeiss telescope is intended mainly for nighttime viewing by the general public, commonly targeting the Moon, planets, and brightest showpiece objects of our galaxy. A popular public destination when special celestial events occur, more people viewed Halley's Comet and comets Hale-Bopp and Hyakutake through the Observatory's Zeiss telescope than any other telescope on the planet.
The telescope itself is in excellent condition and was unchanged by the renovation and expansion project. The copper roof of the telescope dome was repaired and restored, and the dome's drive mechanisms were replaced. The most significant change is the addition of a new exhibit station located in the Hall of the Eye exhibit hall below the telescope dome. The station provides live video and audio feeds from the telescope and allows visitors unable to climb the stairs into the telescope dome to have an observing experience. Most nights, other telescopes also are available on either the roof or front lawn to allow those in wheelchairs to observe directly.
When the night sky is clear, the Zeiss telescope is open from the roof and serves up to 600 visitors per night. One of the Observatory's experienced telescope demonstrators guides the public in looking through the eyepiece of the 12-inch Zeiss refractor (so called because its light is collected and focused by a 12-inch diameter glass lens at the front of the 16-foot-long telescope tube). The main telescope tube carries a smaller 9 -inch refracting telescope piggyback, which permits two different views of a single object, as appropriate.
The telescope sits on a tilted mounting (an equatorial mount) aligned with the Earth's axis, and it is slowly turned by a motor to compensate for the Earth's rotation so that objects remain centered in view for as long as is desired. Counterweights precisely balance the telescope so that the Telescope Demonstrator can easily move the instrument by hand in spite of its 9,000-pound weight. The unique design of construction by Zeiss also counteracts the bending of the telescope due to gravity with counterweighted levers in the telescope's tube and mounting. Such a system is said to be "stress compensated."
The genesis of Griffith Observatory's public telescope occurred when Griffith J. Griffith was invited to visit to Mount Wilson Observatory, then home to the world's largest operating telescope, the 60-inch reflector. While there, he was given the opportunity to view a celestial wonder through the telescope. Profoundly moved by the experience, Griffith seized on the idea of constructing a public observatory with a telescope that could be used by all residents of Los Angeles. He specified in his will that the telescope was to be "at least 12-inches in diameter" and "complete in all its details" and was to be located "high and above the Hall of Science." In 1931, the Griffith Trust ordered the telescope from the Carl Zeiss Company of Jena, Germany; the $14,900 spent on the instrument was the first purchase of material for Griffith Observatory.
For more information about the Observatory's Zeiss telescope, please click here.
Griffith Observatory's three solar telescopes bring the Sun directly to visitors in the west rotunda of the Ahmanson Hall of the Sky. On clear days, each of these telescopes provides a different real-time view of our local star, including sunspots and solar flares. The three beams of sunlight for the telescopes are focused into the rotunda by a triple-mirrored tracking device called a coelostat (Latin for 'sky-stopper'), which is located above in the western dome of the building. The solar telescopes operate only during clear daytime hours.
Coelostats are often used in solar observatories where moving small tracking mirrors is preferable to moving large telescopes attached to heavy equipment. Designed by Russell Porter, whose drawings served as the basis for both the 200-inch telescope at Palomar Observatory and Griffith Observatory, the three mirrors of the Observatory's coelostat move continuously during the day to remain focused on the Sun as it appears to move across the sky. The incoming light bounces off one mirror to another and then down through openings in the rotunda ceiling to the telescopes below. The telescopes show a white light image of the Sun, a view through an H-alpha filter (spectrohelioscope), and a solar spectrum (spectroscope). One of the largest and most-visited public solar observatories in the world, Griffith Observatory has enabled millions of people to observe the Sun safely.
The coelostat instrumentation in the dome and three telescopes housed in the rotunda remain essentially unchanged by the renovation and expansion project, other than new motors for the dome, new electrical service, and restoration of the telescope bronze and optics. A new station in the gallery receives live signals from each of the telescopes to provide an equivalent observing experience for those unable to climb the stairs to the rotunda where the telescopes are mounted.
For more information about the Observatory's solar telescope, please click here.
On any given night, Observatory staff may set up one or more free-standing telescopes on the lawn or East Observation Terrace to enable more people to put their eyeball to the sky. Once a month, the Los Angeles Astronomical Society and Sidewalk Astronomers hold a star party at the Observatory in which many more telescopes are available for public viewing.
In addition, the Observatory has mounted a number of coin-operated telescopes along the south and west perimeters of the building. These devices enable visitors to look at objects in the Los Angeles Basin and surrounding mountains.