This past fall my wife and I had the opportunity to visit the Dublin home of Agnes Mary Clerke. The publisher information on Mary T. Brück’s biography of Clerke, Agnes Clerke and the Rise of Astrophysics (Cambridge University Press, 2002), describes Clerke as the “leading commentator on astronomy and astrophysics in the English-speaking world” at the end of the nineteenth century. She was an astronomer; she made some observations. But her most important work was as a sort of one-woman, multi-lingual, Catholic, information hub.
Clerke has been featured here at Sacred Space Astronomy before:
- Agnes Mary Clerke, M31 and Thomas Aquinas (click here)
- No Such Thing as RANDOM? (click here)
- From the V.O. Faith and Science Pages: Agnes Mary Clerke and the Rise of Astrophysics (click here)
Clerke kept up with what was going on in astronomy in all parts of the world. She communicated personally with astronomers in various languages, helping to make sure that different astronomers knew what other astronomers were doing, especially if their work complemented each other. Some of those astronomers did not get along with each other very well, and would not have been likely to follow each other’s work, but Clerke got along well with everyone, and thus facilitated communication and progress in astronomy. As my wife puts it (my wife has become a big Clerke fan), Clerke was like a library, a librarian, and a good friend to so many astronomers. Clerke also wrote books for broad audiences that contained a lot of cutting-edge information useful to astronomers, too.
Within those books, Clerke made some interesting insights. For example, in her 1908 book A Popular History of Astronomy during the Nineteenth Century, Clerke provided a very clear discussion of the impact that star observations were having on our view of the universe. At the start of the nineteenth century, she wrote, very little was known about stars; astronomers largely viewed the stars as a background against which the motions of planets were measured. Even in the last quarter of the eighteenth century, she wrote, “the sidereal world… was the domain of far-reaching speculations,” unencumbered by systematic study. William Herschel, she noted, operated on the assumption that “the brightness of a star afforded an approximate measure of its distance” — meaning that one star was more or less the same as another; those stars that appeared faint to us he reckoned to be more distant, and those that appeared bright to us, less distant. This assumption meshed with the general idea, popular since the Copernican Revolution, that all stars are more or less identical suns. But it was an assumption. Nothing stood against it, since so little was known about the stars, but there was no science to particularly support it, either — the stars were the domain of speculation, unencumbered by real data.
Throughout the nineteenth century, however, more and more was learned about the stars, largely thanks to advances in technology. Astronomers finally developed telescopes of sufficient quality to be able to determine stellar distances through parallax measurements. By the end of the century, Clerke wrote, the distances to roughly one hundred stars had been measured. Moreover:
the list [of stars with measured distances] is an instructive one, in its omissions no less than in its contents. It includes stars of many degrees of brightness, from Sirius down to a nameless telescopic star in the Great Bear.
Many of the brightest stars had been found to be too far away for their distances to be measured, while most of the stars that were found to be nearest to Earth were quite faint. And so, she wrote,
The obvious conclusions follow that the range of variety in the sidereal system is enormously greater than had been supposed, and that estimates of distance based upon [brightness seen from Earth] must be wholly futile. Thus, the splendid Canopus, Betelgeux, and Rigel can be inferred, from their indefinite remoteness, to exceed our sun thousands of times in size and lustre; while many inconspicuous objects, which prove to be in our relative vicinity, must be notably his inferiors. The limits of real stellar [luminosity] are then set very widely apart.
In other words, stars are not all suns. To be clear, today we understand that the sun is a star. That is, we understand that the sun is a gravitationally-bound globe of dense gas, heated to incandescence by nuclear reactions occurring deep within it; we understand that all stars are these nuclear-powered, incandescent, gas globes.
But as Clerke observed, the range of what counts as a “star” is very wide. We have learned more about more stars in the century-plus since she wrote, but her observation still holds true. There are stars that are enormous, larger than the orbit of the Earth; these are rare. More common are stars comparable to the sun. But most common of all are those stars “notably inferior” to the sun. Of the hundred stars currently known to be the sun’s nearest neighbors in space, roughly eighty have less than one one-hundredth of the sun’s power output. All these combined would not equal the sun, and most are not even visible to the naked eye.
Clerke recognized that the data was showing that diversity was present in the universe, when for so long astronomers had assumed that the universe would be more or less like our world. Clerke was right. As we keep learning about the universe we keep finding out that our planet, our star, and our solar system are not representative of the universe as a whole. Br. Guy Consolmagno and I discuss this (and Clerke) in our new book When Science Goes Wrong: The Desire and Search for Truth (click here for it). I discuss this in my recent paper in the International Journal for Astrobiology: “The Challenging History of other Earths” (click here for it), which I wrote in part because it seems the astronomical community is still having difficulty with this diversity idea that Clerke saw so clearly (and which will be the topic of an upcoming post, a few weeks from now).
Clerke lived in Dublin when she was fairly young. According to Brück (whose book is listed in our Faith and Science Resource Center):
Agnes was 19 and [her sister] Ellen 20 when… their father took up an entirely new profession – in the Law. The post to which Mr Clerke was appointed was that of Registrar at the court of his brother-in-law, Rickard Deasy, newly appointed Baron of the Exchequer.
Brück describes how, after “Catholic emancipation” in Great Britain, Deasy in the 1840s and 1850s had been a barrister, had been elected to Parliament, and held the posts of Solicitor General and Attorney General for Ireland. As Attorney General, he had been responsible for an Act of Parliament, called “Deasy’s Act” (1861), “which attempted to solve one of Ireland’s most intractable problems, that of relations between landlords and their tenants”, but which accomplished little. Deasy resigned his seat in Parliament in 1861 when he became Baron of the Exchequer, and, in that role, one of the country’s first Roman Catholic judges. The Clerkes moved to Dublin for Mr. Clerke’s new job with Deasy. As Brück describes things, it was pretty nice living:
The Clerke family home was at 12 Herbert Place, a spacious terraced house on the fashionable south side. Herbert Place is one of Dublin’s most beautiful and dignified Georgian streets which still stands unspoiled. The Grand Canal, which was then a busy route for commerce, runs parallel to the terrace on the opposite side of the road. From the windows of the houses the inhabitants could watch the barges on the canal, and could take the same pleasant walks along the canal bank as the citizens of Dublin do today. The canal and its environs have strong associations with the literary world. A novelist of a later era, Elizabeth Bowen, was born in Herbert Place, a few doors away from where the Clerkes once lived; the canal bank nearby was a favourite haunt of the twentieth-century writer Patrick Kavanagh, to whom a statue and memorial bench have been erected in recent times….
The hallway [of #12 featured a] sweeping staircase, illuminated by a large window, the drawing room on the first floor and the bedrooms above. In a design typical of many of the Dublin Georgian houses, the entrance was reached by a flight of outside steps, under which was the entrance to the lower floor at street level.
Herbert Place was not far from Judge Deasy’s residence at 27 Merrion Square, the best address in Dublin. He had recently married, and the two families were to remain very close, though the Deasy children were considerably younger than their cousins.
Herbert Place still is pretty nice. When we visited #12, it was for sale — for €2.5 million! The realtor’s website allowed for a virtual tour. We could see the staircase and everything else that Brück describes. You too can still get a look at the Clerke home via that website — click here!
My wife and I were really pleased to be able to visit this little bit of astronomical history (unmarked — there’s no plaque saying “Agnes Clerke lived here”, and the realtor selling the place does not mention Clerke, either). And when we were there the moon was just visible off the top of #12 — fittingly enough for the home of Agnes Mary Clerke!
