This week sees the centenary of the death of Irish astronomer Agnes Mary Clerke, probably the most famous woman working in the field in Victorian times, writes Dick Ahlstrom.
One of the leading chroniclers of astrophysics and astronomy through the later part of the 19th century was an Irish woman. Self-taught and with no formalised education, Agnes Mary Clerke had a tremendous impact on the field and her most famous work is still being reprinted.
Last Saturday marked the 100th anniversary of her death in London where she lived and wrote about astronomy for several decades. But she was born in Skibbereen, Co Cork in 1842 and lived in Dublin and later Florence, Italy.
Her father was a bank manager in Skibbereen and a Trinity College graduate. Her mother was an intellectual with a talent for music, says astronomer and Clerke biographer Dr Mary Bruck, a UCD graduate originally from Ballivor, Co Meath who is better known in Ireland as Marie.
The parents decided to educate Agnes and her sister Ellen at home. The two sisters were brought to an academic level unusual for women of that generation, and this self-education continued in Dublin and later when the two sisters left Ireland to live in Florence for 10 years.
Clerke spent her time studying in the city's libraries, says Bruck. "It was at the time the Galileo papers were released. They were being collected by the scholars in Florence. Agnes was in Florence at that very interesting time."
During this time, Agnes developed a keen interest in Renaissance astronomy and, after her move to London in 1879, she began submitting articles on Galileo and Copernicus to the Edinburgh Review. She also began writing scientific biographies in the Encyclopaedia Britannica on figures such as Galileo and the French mathematician Pierre-Simon Laplace.
"After a few years she was asked would she review a number of books on astronomical spectroscopy and she just got completely hooked," says Bruck.
She began teaching herself modern astronomy and physics and began to write regularly about astronomy in journals including Nature, Observatory and Knowledge.
These were the early days of astrophysics, when astronomy began to link with the development of theories on the formation of the Milky Way and the universe based on data from observations.
"She was a self-taught expert in astronomy and particularly astrophysics," says Bruck. "She had a brilliant mind, she was able to figure it out."
These studies launched Clerke on her greatest work, a book for both the layman and the scientist about the latest developments in astronomy. "She didn't tell anyone about what she was doing until, after four years, she published A Popular History of Astronomy during the Nineteenth Century," explains Bruck.
"The History was a sensation. The first person to review it was Sir Robert Ball, who gave it tremendous praise."
Her great achievement in the History, published in 1885, was to take the latest advancements in the science of astronomy and cosmology and make it understandable to a lay readership while retaining its scientific content and accuracy for the specialist, says Bruck.
"For a quarter of a century she was the leading commentator on astronomy and astrophysics in the English-speaking world, and widely regarded as an exceptional communicator of astronomical discoveries," says University College Cork astrophysicist Dr Paul Callanan. "Think Patrick Moore or Carl Sagan, except female and Victorian."
Astronomers also sought her out, hoping she would write about their discoveries, says Bruck. "They all wanted Agnes Clerke to know about their work because it was a sure way to get it published in London."
She wrote other important books, including The System of the Stars (1890) after spending time at the Royal Observatory, Cape of Good Hope, the only time in her career she conducted astronomical observations.
Agnes Clerke's third major book, Problems in Astrophysics (1903) attempted to identify unresolved questions, particularly in stellar spectroscopy, says Bruck. She also wrote 150 biographical entries in the original volumes of the Dictionary of National Biography.
The History remained her greatest accomplishment, however. "She made astronomy accessible to people but without over-simplifying it. She had the gift of writing prose that was, scientifically, completely correct," states Bruck.
It went into three editions in her lifetime, each one fully updated with the latest discoveries, says Bruck. "It was the last word on cosmology until about 1920." Its latest reprint was as recently as 2003.
Agnes Clerke died of pneumonia, aged 65, at her London home on January 20th, 1907. She is buried in the family plot in Brompton cemetery, London.
Bruck speaks with some authority on Clerke's accomplishments. Bruck completed her PhD in Edinburgh before a stint at Dublin's Dunsink Observatory before marrying its director, Dr Herman Bruck.
He later became Scotland's Astronomer Royal and the director of the observatory at Edinburgh, where she worked on the staff and also lectured at the University of Edinburgh.