About forty miles southwest of Tucson, on a site nearly 7000 feet above sea level owned by the Tohono O'odham Indians, is one of the largest and most diverse astronomical observatories in the world. With a perpetual lease from the tribe, the observatory opened in 1958 following a comprehensive search for a suitable location. The site now operates 24 different observatories, including the largest solar telescope in the world. Visitors are welcome to visit and tour the grounds on their own without charge. Three guided tours are available during the day, while several levels of night programs are offered. I spent the entire day there, taking all three guided tours and walking several miles up and down the roads to see the various observatories. It was a workout similar to hiking a large canyon. The roads are laid out not for the convenience of visitors, but to drain all rainwater and snow melt into a catch basin. This is the only source of water on the mountain!
A spur road off the highway to Ajo leads up the mountain to the observatory, some twelve miles away and almost 4000 feet higher. That equates to an average grade of roughly six percent on a twisting, narrow road with sheer drops and few guard rails. The drive up presented some good views of the peak itself, as well as the surrounding countryside. It really drove home how the various mountain ranges just seem to pop up out of the flat desert terrain.
The solar telescope is more than 100 feet high above ground, but continues for a couple hundred feet into the earth, with a mirror increasing the light path to 500 feet. Two posters show the design of the telescope. (The second poster included a reflection of the site's largest observatory, about half a mile away.)
The actual telescope, of course, could not be photographed in its entirety.
The 4 meter telescope, which means its mirror diameter is 4.1 meters (just over 13 feet), was the second largest in the world when installed, but has now been surpassed by several others. Its building is 180 feet high, with massive machinery to house the mirror and related gear, to rotate and open the dome, and to be operated remotely. The dome was rotated for our tour, a very impressive operation.
While I was unable to photograph the interior of the observatory, I did get a photo of the poster showing the equipment inside. Notice the people standing near the mirror housing. Also, from inside the building, I got a pretty good view of the mountain top and many of the observatories scattered about.
In this next photo, lower right, is one of two radio telescopes in use at Kitt Peak. It captures images via radio waves, rather than light waves. It can be combined with other radio telescopes around the world through communication links, with the combination producing much greater strength than a single instrument.
At the visitor center, a mural on an exterior wall pays homage to the Mayans, who built one of the earliest observatories at Chichen Itza, Mexico around 900 AD. The circular element at bottom center represents the design of the Mayan observatory, while the mural also depicts the sun, thee moon and several planets. The Mayans were able to predict lunar and solar eclipses, and developed a calendar more precise than the Gregorian calendar in use currently.
Also on display is the "mock" four meter mirror, made of concrete, that was used in the construction of the observatory while the real mirror was still being created. The artwork that has been added honors the Tohono O'odham tribe for allowing the observatory to be built on its reservation. Incidentally, the reservation is the second largest in the country, encompassing about three million acres, roughly the size of Connecticut.
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