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By Blog Master
Posted: 05/31/2022

The Carnegie Observatories

Did you know that the oldest scientific institution in Pasadena can be found on a quiet residential street in central Pasadena?  The main offices of the Carnegie Observatories are located in Pasadena on Santa Barbara Street, with about 65 scientific, support, and technical staff in residence. Last month, a group of Pasadena Village members were privileged to visit the facility on a tour led by Dr. Jeff Rich, Outreach Coordinator, and Erica Clark, Strategic Initiatives Coordinator.

On our tour we learned how, in 1904, George Ellery Hale (founder of Caltech), whose motto was “make no little plans”, obtained support from the newly formed Carnegie Institution of Washington to build the Mount Wilson Solar Observatory in the mountains near Pasadena.  Dr. Hale, one of the founders of modern astrophysics, was determined to push beyond the astronomy of earlier generations to understand the internal physics of the Sun and the stars.  In pursuit of this goal, stellar telescopes soon followed the initial complement of solar telescopes on Mount Wilson: first the 60-inch, then the 100-inch Hooker telescope, each the largest in the world at the time of its construction.

The Mount Wilson telescopes transformed astronomy and astrophysics. It was with these instruments that scientists first mapped the globular cluster system of the galaxy and “discovered” the Milky Way. With the aid of the 100-inch telescope Edwin Hubble then discovered that the Milky Way is only one of millions of galaxies in an expanding universe.

We learned about Milton Humason, who dropped out of school and had no formal education past the age of 14. Because he loved the mountains, and Mount Wilson in particular, he became a "mule skinner" taking materials and equipment up the mountain while Mount Wilson Observatory was being built. In 1917 he became a janitor at the observatory where he volunteered to be a night assistant at the observatory. His technical skill and quiet manner made him a favorite on the mountain. Recognizing his talent, in 1919, George Ellery Hale made him a Mt. Wilson staff member. This was unprecedented, as Humason did not even have a high school diploma. He soon proved Hale's judgment correct, as he made several key observational discoveries and was instrumental in assisting Hubble in his key discoveries. In 1950 he earned a D.Sc. from Lund University. 

Dr. Rich explained how, as the night skies surrounding Pasadena became less dark, the ability of the Mt. Wilson telescopes to “see” into the night skies diminished. Thus, in 1970 the Carnegie Observatories began constructing the Las Campanas Observatory located in the Atacama desert in Chile, in a region of dark and clear skies and excellent viewing unsurpassed by any site on Earth.  

Fifty-two hundred miles from Chile, scientists and administrative personnel in Pasadena analyze and study the data coming from the faraway telescopes. The scientific staff of about a dozen Staff Members, and an equal number of postdoctoral fellows and associates, have access to time on the institution's four telescopes. The principal telescopes at Las Campanas are the Swope 1-meter telescope (named after astronomer Henrietta Swope), the du Pont 2.5-meter telescope, and the twin 6.5-meter Magellan telescopes. Carnegie operates the latter for a consortium whose other members are Harvard, MIT, and the Universities of Arizona and Michigan.  

Our group walked through the machine shop where most of the instruments for the Las Campanas telescopes are designed and built under the direction of Carnegie astronomers, including the broad suites of optical and near-infrared cameras and spectrographs. Work at the machine shop also continues to craft cutting edge equipment to aid in the science, including equipment that allows modern day cameras to take a new look at the data gathered in the past.

Though a succession of earthquakes felled many of the early buildings, the original 1912 office building still stands. This building, designed by Myron Hunt, houses the library and offices. We made ourselves comfortable in the book-lined library as we listened to Dr. Rich and Ms. Clark describe the work and interactions of scientists including Albert Einstein. Although the walls are lined with books, today everything is done digitally. We learned that the basement contains historical documents including the photographic plate upon which Carnegie astronomer Edwin P. Hubble captured the image of the Andromeda Galaxy (Messier 31) with the Hooker 100-inch telescope of the Mount Wilson Observatory. Only two people know the exact storage location of this historic photo that is known as “the photo that changed the world”, as it was evidence that there are more galaxies than we had ever imagined.

In order to continue to attract the best scientists, staff members and research fellows at the Pasadena campus have no other responsibility than to do great science; neither teaching, nor the search for outside funding, nor any other institutional priority need distract them from their own intellectual goals. It is this exceptional environment, nestled away in a quiet area of Pasadena that has enabled the relatively small Carnegie staff to make such disproportionately large contributions to astronomy.

All of us on the tour came away impressed by the breadth and scope of the Carnegie Observatories research and impact on our understanding of the universe. Research fellows like Dr. Rich demonstrate the commitment and willingness to engage in what to us is mind boggling ideas. We are indeed fortunate to have this resource in our community.

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