Newer, fainter, and more distant things

The life and times of the Cape Town Observatory.
By | Published: October 24, 2017 | Last updated on May 18, 2023
The McClean Dome and Victoria Telescope.
Shaun Cameron
4.24 light-years from Proxima Centauri, 150 million kilometers from the Sun, 385 thousand kilometers from the Moon, and 6,000 nautical miles from the Royal Observatory in Greenwich sits the chalky-white cluster of buildings housing the South African Astronomical Observatory (SAAO).

Known as the Royal Observatory at the Cape of Good Hope until South Africa assumed two-thirds ownership in 1972, the observatory became so synonymous with this picturesque corner of Cape Town that the surrounding area appropriated its name. Say “observatory” to most Capetonians now and they’ll direct you to an eclectic and bohemian conurbation bordering the Salt River in the northeastern corner of the Western Cape. The SAAO itself is tucked quietly away on a hill in this suburb, calm and stately on a cool and sunny August day, the dramatic mountainscape of Devil’s Peak and Lion’s Head puncturing the sky on the western horizon.

Two centuries ago, the lush trimmed lawns of the SAAO complex were cattle pastures surrounded by disease-ridden swamps, the main building still a twinkle in the eye of a naval power casting increasingly amorous eastward glances. The British Empire invaded the Cape in 1806, and its navy needed a Southern Hemisphere observatory somewhere along its trading route to the Orient. Exploration of choppy southern waters could be perilous, and the development of sophisticated navigational equipment was still in its infancy; ships could sometimes find themselves hundreds of miles off-course.

Dr. Glass.
Shaun Cameron
“When ships sailed from England at that time, chronometers were very important for longitude determination,” says Dr. Ian Glass, an infrared astronomer and scientific historian who has worked at the observatory for 40 years, and is author of a book on its history and heritage. “They were very expensive, and were not all that reliable — they were clockwork — so a typical naval ship might have three or five chronometers on board, in case one went haywire. When they got here, one of the things they wanted to do was set the chronometers and get a new time.”

The accurate resetting of chronometers required reliable time signals from a static station; scientists based at the proposed observatory would measure time using pendulum clocks and star positions, providing a standard chronological marker for vessels moored in Table Bay. This time would then be visually communicated to the ships by firing a flare pistol and dropping a colorful time ball on the observatory grounds (a cannon is still fired every day at noon on Signal Hill near Table Mountain).

So it was perhaps fortuitous that imperial demand had overlapped with scientific appetite, which had long coveted an opportunity to properly map the Southern Celestial Hemisphere. Few, however, would volunteer to undertake the grueling task of overseeing the construction of the initial buildings and taking receipt of the first items of equipment. This responsibility fell to a British mathematician with the swashbuckling name of Fearon Fallows, who survived in the feverish and insanitary conditions just long enough to witness the completion of the main building — an impressive classical structure with teak floors and window frames, which now accommodates the observatory library (home to a 500-year-old copy of Ptolemy’s Almagest).

The grave of Fearon Fallows.
Shaun Cameron
“The story is that he was asked to be buried very deep, 14 feet down,” says Glass. “Apparently the standard thing in English or Scottish wills in those days was to specify a deep grave, because of grave robbers.” His Majesty’s Astronomer is honored with an elegant engraved slab a few feet from the SAAO’s most recognizable building, the sedate McClean Dome. “He only really got going with the main instruments about 1828, so he only had about three years before he died. But he got the instruments nicely set up for his successor, Thomas Henderson, who was able to use them very successfully. He [Henderson] was the first person to measure the distance to a star, Alpha Centauri, using these instruments, and it’s really thanks to all the hard work that Fellows had put in.”

Over the course of its close to 200-year history, the observatory has hosted an impressive array of scientific trailblazers. Thomas Maclear, His Majesty’s Astronomer between 1833 and 1870, modified the famous French astronomer de la Caille’s assertion that Earth was pear-shaped (Maclear showed it is oblate and symmetrical, though American astrophysicist Neil deGrasse Tyson has recently suggested it may indeed be slightly portlier below the equator).

Dr. Cunnama and Dr. Glass in the observatory library.
Shaun Cameron
Maclear was also mentor to a brilliant young astronomer named Charles Piazzi Smyth, who had a keen interest in a photographic process known as the calotype. Piazzi Smyth is now regarded as the pioneer of South African photography; his work would have been an inspiration to David Gill, the watchmaker-turned-astronomer who presided over the observatory at the dawn of the 20th century. Gill fostered a halcyon period of innovation and discovery. He was instrumental in pushing forward an expensive and costly project cataloging the southern stars using photographic plates, a process that years earlier had been undertaken as essential but laborious observations of the positions of single stars.

“They employed a lot of people called computers — that was their job, to just work out figures,” says Glass. “And they mostly wanted youngsters who had a good head for figures, but they would go crazy after a few years — they wouldn’t last very long doing this. Then photography became the technique of choice, and this place became a world center for photography, so some of the earliest photographic sky maps were made from here.”

In 1896, Gill secured funding for the construction of the 36-foot McClean Dome, which houses the Victoria Telescope, the largest on the compound. The trichotomic telescope was retired in the early 80s but remains fully functional, and the star of the regular open nights co-organized by Dr. Daniel Cunnama, a computational astrophysicist who also contributes to the observatory’s busy outreach program.

Dr Glass and the Victoria Telescope.
Shaun Cameron
Visits from school parties are frequent during the week, and the biweekly open nights often attract upwards of 200 people. Cunnama is well versed in the astronomical conundrums at the forefront of these young minds. “We get through about 35,000 school kids a year,” he says. “There’s been a lot of interest in Mars — this comes from recent movies, and then obviously Elon Musk talking about sending humans to Mars in the Mars One program. So I get quite a few emails about Mars and ‘Can we really go there? Are we going there?’ The scales of distance when we talk about the nearest star, or going to Mars, or the nearest black hole, are extremely large, so that’s something that I try and get across: the enormity of space.”

The observatory also embraces concepts rooted in ethnoastronomy, an important allegorical compass for many African cultures with its own intricate cosmology of meanings and function. “I think it’s very important to understand it and engage with it, rather than push against it,” Cunnama says. “This sort of indigenous knowledge, these beliefs and understandings of the stars, of the universe, they’re important, in the same way that in western civilization we take for granted the cultural or societal knowledge we have, which isn’t necessarily taught at school. To not incorporate other societies’ cultural knowledge into your teaching is very short-sighted.”

Dr. Cunnama and the 1833 flare pistol.
Shaun Cameron
The modern world has had a more damaging effect on the usable data of the observatory itself, and the deleterious impact of air and light pollution became difficult to ignore by the early 1960s. Site testing soon began in the clear-skied desert region of Karoo, and by 2005 the town of Sutherland had become home to SALT: the South African Large Telescope, the largest optical telescope in the Southern Hemisphere.  The Cape Town site is now home to data reduction facilities and a small but fascinating museum housing some of the original equipment from the earliest days of the observatory.  These exquisitely crafted bronze and wood artifacts from a bygone age — the 19th century signaling pistol is reassuringly heavy in the hand, but filigreed with the airiest of decorative inscriptions — are a universe away from the AI-assisted number crunching of modern astronomical calculations.

“Faced with the task of having so much data, one individual human cannot process that sort of information,” says Cunnama. “You can’t look at 100 million galaxies and try and work out what is interesting. Whereas if you can have some kind of machine learning algorithms that can process this data, look for interesting features, and identify them for you, you can then maybe understand better what’s going on.” Global astronomy’s mothership project, the jointly-financed Square Kilometer Array, is set to plant one foot in the Karoo in 2018, and is projected to boast the computing power of 100 million PCs.

Dr. Glass.
Shaun Cameron
These gigantic shifts in scale, generations after a sickly and overworked Fallows first set up a temporary home in an inhospitable corner of the Cape, are perhaps too staggering for the human brain to comprehend. But they still share a common impulse, a communal curiosity.

“The thing about discoveries is that you don’t know what to expect,” says Glass. “There’s always a problem when you have a new instrument like SALT or the SKA — you expect because of its sheer size it’s going to find newer, fainter, more distant things, but you don’t know ahead of time.”

He’s about to be interrupted by the boom of the noonday gun on Signal Hill, 25 seconds away.

“Otherwise… what’s the point of doing it if you know what you’re going to get?”

Dr. Glass’ book, The Royal Observatory at the Cape of Good Hope, can be purchased by contacting Dr. Glass at

Dr. Glass in front of the McClean Dome.
Shaun Cameron