100 years ago, 'telescope of huge size' launched UArizona's leading role in astronomy

On Saturday, the community is invited to an open house celebration to rededicate Steward Observatory to continuing its education, outreach and research missions. 

By Daniel Stolte, University Communications
April 19, 2023

36-inch telescope.jpg

The original 36-inch telescope installed in the dome at Steward Observatory
The telescope that started it all: At the time nicknamed the "All-American" because it was the first astronomical telescope built using domestic-made products, it is still being used today to keep track of comets and asteroids.

On April 23, 1923, the University of Arizona community, distinguished visitors and Andrew Ellicott Douglass, the first director of Steward Observatory, gathered on campus to celebrate the dedication of a new "telescope of huge size." With a primary mirror measuring 36 inches in diameter, the new telescope allowed for the start of major astronomical research, student education and public outreach by the university. The new observatory was made possible by the generosity of Lavinia Steward, whose historic gift of $60,000 funded its construction.  


Historic photograph of the Steward Observatory dome
At the it was built, the Steward Observatory dome was located outside of the university campus, on a former ostrich farm.

"During his dedication speech for the observatory, Douglass articulated his aspirations for the future use of the telescope and the observatory," said current Steward Observatory director Buell T. Jannuzi, the seventh person to hold the position. "Douglass got us started on a wonderful mission, and it still is the same that he envisaged. Our students and faculty – with support of the talented staff of Steward Observatory and the Department of Astronomy – explore the universe and share what we learn with the rest of the world through our courses, publications and our public outreach activities. The last 100 years of our public telescope viewings and our public evening lecture series reflect this commitment." 

Other public outreach facilities under the Steward Observatory umbrella include the Mt. Lemmon SkyCenter science learning facility and the Sky School, which provides science education programs to K-12 students in Arizona. 

Douglass anticipated that the astronomical endeavor at the university would grow over time and require adding new facilities. Over the past century, Steward Observatory and the university as a whole have grown and developed into a world leader in space sciences, said Jannuzi, also a professor and head of the university's Department of Astronomy.

"The students, staff and faculty of Steward Observatory now number more than 300 people," Jannuzi said. "We have added many facilities to the original 36-inch telescope."

UArizona now operates more than a dozen telescopes across the state and has helped build and operate observatories in Chile, Antarctica and even in outer space. The university is a partner in three observatories featuring large telescopes with 6.5-meter primary mirrors made in Steward Observatory's Richard F. Caris Mirror Lab: the two Magellan Telescopes in Chile and the MMT (formerly known as the Multiple Mirror Telescope) on Mount Hopkins just south of Tucson. Steward also operates two millimeter/submillimeter telescopes through the Arizona Radio Observatory. Steward also is a partner in the Large Binocular Telescope Observatory. Located on Mount Graham in southeastern Arizona, the LBT is the world's largest optical telescope, boasting two 8.4-meter primary mirrors that were also made at the university's mirror lab.


Technicians at the Richard F. Caris Mirror Lab load chunks of glass in preparation of casting one of the primary mirrors for the Giant Magellan Telescope.
Technicians at the Richard F. Caris Mirror Lab load chunks of glass in preparation of casting one of the primary mirrors for the Giant Magellan Telescope.

"Together with the activities of our sister space science units – the Lunar and Planetary Lab and the Department of Planetary Sciences – we have a huge economic impact on the state of Arizona totaling $560 million annually," Jannuzi said.

On Saturday, the community is invited to an open house celebration at 1 p.m. at the observatory to rededicate Steward to continuing its education, outreach and research missions. 

"We will celebrate our first century of astronomical research and look forward to the next century," Jannuzi said. "We will also celebrate the ongoing legacy of the original 36-inch telescope."

Despite being a century old, the telescope that started it all is still being used today. At the time nicknamed the "All-American" because it was the first astronomical telescope built using domestic-made products, it was later moved to Kitt Peak, known to the people of Tohono O'odham Nation as I’lokum Duag, after the site was developed for astronomy by Kitt Peak National Observatory. Currently, the telescope is on duty with the Spacewatch Program. Founded in 1980 by UArizona planetary scientists Tom Gehrels and Robert McMillan, the program has played a key role in keeping track of asteroids and comets that could someday pose a hazard to Earth. Spacewatch is led by lunar and planetary research scientist Melissa Brucker.

Jannuzi said he looks forward to new facilities in development, and said he is grateful for the support the university has received from generous donors.  

"In 1923, a 36-inch telescope was pretty cutting edge," Jannuzi said. "But a century later, we needed another generous philanthropist to help us, and Richard F. Caris came forward to keep astronomy evolving and growing at the university." 

Caris, in addition to providing funding that supported the


Daytime rendering of the Giant Magellan Telescope, or GMT
Here pictured in a rendering, the Giant Magellan Telescope will be one of the world's largest telescopes once completed. All its seven primary mirrors are being manufactured at Steward Observatory's Richard F. Caris Mirror Lab. Giant Magellan Telescope - GMT Corporation

development of the Mt. Lemmon SkyCenter, provided $20 million that allowed UArizona to become one of the founding partners of the Giant Magellan Telescope Organization. In recognition of this gift, Steward Observatory's mirror lab, founded by Regents Professor of Astronomy Roger Angel, was renamed in honor of Caris. Scientists and technicians at the lab fabricate gigantic mirrors for the next generation of astronomical observatories, including the Vera C. Rubin Observatory and the Giant Magellan Telescope, both in Chile

Always hungry for the next breakthrough in observing technology, Steward astronomers point to the quest of finding Earthlike planets around other stars as the "big holy grail." Once completed and operational, the Giant Magellan Telescope will make it possible to address ambitious research challenges such as trying to understand the nature of dark matter and dark energy; how matter first formed in the universe and how it came together to form stars and galaxies; and whether stars came before galaxies or vice versa. 

"We look forward to the next 100 years," Jannuzi said. "Our programs continue to grow, because our students have a unique opportunity to pursue their ideas at such an early stage of their careers. During these formative stages of development, our students have access to all our facilities, observatories, and computing resources to pursue their research. We provide them with the chance to succeed and fail as they grow the skills, experience and confidence necessary to take on the challenging problems of the future."

Extra info

A rededication ceremony will be held on Saturday, April 22 from 1-5 p.m. at the Steward Observatory Dome and Steward Room N210. Campus community members, the public and distinguished guests are invited to celebrate Steward Observatory's continuing mission in education, outreach and research.

University of Arizona Land Acknowledgement:

We respectfully acknowledge the University of Arizona, including our observatories, are on the land and territories of Indigenous peoples. Today, Arizona is home to 22 federally recognized tribes, with Tucson being home to the O'odham and the Yaqui. Committed to diversity and inclusion, the University strives to build sustainable relationships with sovereign Native Nations and Indigenous communities through education offerings, partnerships, and community service.


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Daniel Stolte

Science Writer, University Communications