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  • Writer's pictureDale DeBakcsy

Making Spectroscopy Hip: Agnes Mary Clerke at the Nerve Centre of 19th Century Astrophysics

For a solid century and a half, from Mary Somerville’s The Mechanism of the Heavens of 1830 to Helen Sawyer Hogg’s final With the Stars column in 1981, it was largely from women that the English speaking world learned its love of the night sky and its inhabitants. Somerville (1780–1872) had brought continental mathematics and celestial mechanics to an England that had been experiencing a heavy intellectual drought since the time of Newton, and Hogg (1905–1993) was for decades the steady and reliable popular source for enthusiasm about backyard astronomy and the cosmos beyond, but filling the void between them was perhaps the most important figure in the coordination, advancement, and popularisation of 19th century astronomy, Agnes Mary Clerke (1842–1907).

She lived during the tectonic shift of astronomy from a concern of enthusiastic, privately funded amateurs to the state-funded, big equipment, mountaintop observatory profession of the modern era, and was one of a handful of people not to get swallowed and obliterated in the transition. You don't have to look very hard to see why. She was a master of languages, and knew Latin, Ancient Greek, German, Italian, and French on top of her native English. She once learned Portugese in six weeks because she had some technical articles in that language she wanted to reference.

Apparently that's something people can do.

That easy command of the world’s major past and present languages of science made her the foremost historian of astronomy’s past as well as the most gifted, widely read, and internationally connected chronicler of its rapid late-century advancement.

She read everything and kept connected with everyone. Pickering at the Harvard Observatory, Gill at the Royal Cape Observatory, Hale at Yerkes, Wolf at Heidelberg, Holden and Barnard at Lick – these were the great names at the great observatories, and all of them checked in regularly with Clerke as their point of contact with the detailed goings on of the larger astronomical community. She received results from the world over before they were published and acted as the spokesperson for a field rapidly growing more complicated than the popular astronomy periodicals could simply convey. She saw clearly the value of spectroscopy (using the tell-tale elemental lines of a star’s light to identify star composition and direction of motion) to revolutionise how astronomy was done, and promoted it with eloquence and infectious passion.

It was a calling honestly come by – her father was an enthusiastic amateur astronomer who used precise astronomical measurements to calibrate the main clock of the town where he worked as a banker. His shelves were filled with texts on astronomy and mathematics and he devoted himself to personally educating all of his children, giving them a grounding in science, mathematics, the classics, and history that far outstripped the standard school curriculum for boys, not to speak of its titanic improvement over the Knitting And Dancing curriculum that British girls of the age could expect as the summit of their education.

After moving from Skibbereen to Dublin at the age of 19, Agnes added piano to her growing list of abilities, and would eventually meet and perform for Franz Liszt and study under a student of the legendary Berlin Philharmonic conductor Hans von Bulow. Making music was to be a lifelong love of hers, though she rarely overcame her shyness to do so for others. Meanwhile her brother Aubrey studied astronomy at Trinity College and brought home the newest developments in the field to be eagerly devoured by the star-mad Clerke clan.

In 1867 she had a chance to witness the birthplace of modern astronomy firsthand when her family moved to Italy, there to stay for a decade. Agnes absorbed languages and history and took particular advantage of the open libraries to research the Italian masters of the cosmos, chief among them the complicated story of Galileo Galilei. The notes she took and sources she investigated stood her in good stead when she returned to England and began, with her sister, a career as an author. The caliber of her research and depth of her sources, combined with a native gift for writing, opened doors immediately to all the best periodicals of the day. In a story we don't often get to tell in Women in Science, instead of spending decades clawing for slivers of recognition, she enjoyed the sight of journals falling over themselves to feature her writing.

She made easy friends of editors, publishers, and members of the tight-knit international group of astronomers who were at that very moment working a revolution, and produced a stream of deeply researched articles about the modern state of science, as well as its deep past, totally unique in the science literature of the age. This was the time when astronomy was making the great spectroscopic shift, spreading out the spectra of starlight to determine what atoms were present and, after the application of Red and Blue Shift, what direction stars might be traveling relative to the Earth. With one method, astronomy went from the painstaking but relatively robotic categorisation of points in the sky to a deep knowledge about the chemical constitution and likely motion of those points, and Clerke was there to document these exciting early steps.

She wrote for The Edinburgh Review, Observatory, Nature, Knowledge, The Dictionary of National Biography, and the Encyclopedia Britannica, dense articles about new scientific developments culled from her network of contacts at the world’s major observatories and her constant review of the scientific literature in four different languages. Keeping up with her extensive correspondence, visiting foreign observatories, entertaining visiting astronomers, and honouring her journal deadlines consumed masses of time, but somewhere in the midst of it all she also managed to write four books that, between them, both immaculately summed up the past astronomical age and gave shape and direction to the coming one.

A Popular History of Astronomy in the Nineteenth Century (1885) was her first book-length summation of astronomy’s shift from star counting to star analysis, and it was, in spite of its unusual wealth of detail, a popular smash that went through four editions in two decades and long remained (and in some universities, remains) the standard history of the subject. She followed it up with The System of the Stars in 1890, which sought to sum up all the leading knowledge and theories about the nature and formation of stars, nebulae, and ultimately the universe itself. She was repeatedly honoured for the contribution these books represented to the cause of science – works of enough depth for professional astronomers to learn more about the breadth of their field yet written clearly enough for amateur enthusiasts to follow and take inspiration from.

But it was her third book, Problems in Astrophysics (1903), that saw her breaking new ground. After years of observing, communicating, and synthesizing information from the world over, she felt it was time to put her storehouse of knowledge to positive use by setting out a definitive account of open questions to be pursued along with suggestions about how the new wave of observational technology could be employed to answer those questions. She had been long privately pushing her astronomer friends to adopt various projects with regard to variable stars and peculiar spectra, but here at last she set a towering program of research before the astronomical community. It was an accomplishment of such obvious importance that the Royal Astronomical Society had no choice but to break its over sixty year ban on honourary memberships for women to bestow one on her.

All of her books were received with almost unilateral critical praise and popular appreciation, with Europe’ and America’s most esteemed astronomers reviewing each in words of unchecked admiration. She was seriously consulted for her opinion on astronomical problems by the age’s most significant scientists, and her work would continue to be referenced in scholarly circles for a century after its original publication. Cripplingly shy of social encounters and public speaking, she never sought or accepted a research or academic position, but kept to what she enjoyed best: sitting in her study and letting her brain reach out to the world through the printed word that had been her constant companion since her father placed book after book in her young hands and urged her to use them to explore the history of man and universe.

She died in 1907 of influenza, and the astronomical community mourned the loss as one in tribute papers and obituaries. She was the greatest synthesiser of England’s great age of self-taught astronomy enthusiasts, and her death closed the book on a heroic era of daring expeditions and backyard observatories that, through sheer chutzpah and ingenuity, pushed us into a new understanding of what astronomy could do and say. She gave astronomy a sense of its fertile past and pushed it into a full appreciation of its coming potential, and took the rest of us along for the ride. And all it took was a pen, some books, some paper, and a mind ready at every moment to learn something new.


Mary Brück was the great historian of English and Irish women astronomers of the 19th century, and her book, Agnes Mary Clerke & the Rise of Astrophysics (2002), is the place to go for Clerke, but if you can find it a neat follow up is her Women in Early British and Irish Astronomy: Stars and Satellites (2009) though, man, good luck finding a decently priced one.

And if you'd like to read more about women astronomers like Jill Tarter, check out my History of Women in Astronomy and Space Exploration, which you can order from Amazon, or from Pen and Sword US or UK.


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