Tag Archives: history of astronomy

February Skywatch


It’s been an exciting month for skywatchers! Last month I talked about some of the easy sights for backyard telescopes in the constellation Orion, which is looming large in our evening skies. The first couple weeks of February though, offer an even more impressive naked-eye sight in our morning sky: the possibility of glimpsing all five visible planets arranged in a straight line across much of the sky. The arrangement is best right now and will continue throughout the first week of February.

Standing outside before dawn, look to the east. Venus is bright above the eastern horizon, and if you have a clear view you may catch elusive Mercury even lower toward the Sun’s glow. Saturn is above Venus to the south, with Mars riding high in the southern sky. Jupiter is the bright object beyond Mars, toward the southwest. Altogether, the planets make a lovely arrangement that spreads across nearly the entire southern skies. The best time to look for them is just before sunrise, around 5:30 to 6:30, at which time the Sun’s glare begins to wash them out.

The mornings of this first week also bring an additional sight to the arrangement: a lovely slender crescent moon which passes by Mars on February 1st, is near Saturn by the morning of the 3rd, and moves down toward Venus on the 5th. An arrangement like this, with all the planets neatly in a row along the ecliptic, is fairly rare, so make an effort to rise early and take a look at this vista of the closest worlds of our solar system.

I mentioned last month I’d spend this column talking about telescope basics, but planetary happenings are enough to push that back a bit. Besides the arrangement of visible planets, astronomers grew quite excited this week with news of new evidence that might indicate the existence of an undiscovered ninth planet in our solar system.

When you look up at the pre-dawn sky this week, you can see all the visible planets in our solar system, which are all the planets that were known throughout most of history. It was only in the late 1700s that we began to realize there were other planets in our own backyard, and this most recent announcement may herald that our family of planets is about to expand again, for the first time in over a century.

All of this obviously makes astronomers pretty excited but also cautious, as there have been lots of false claims for Planet X in the past.

Until William Herschel stumbled upon Uranus in his telescope sights in 1781 and subsequent calculations showed that it wasn’t something like a comet, Saturn was considered the outer boundary of our planetary system. As astronomers observed the new planet though, they eventually realized that something was causing it to speed up and slow down in its orbit. The French astronomer Le Verrier correctly deduced that this was caused by an additional planet in our solar system and predicted its location, and Neptune was thus discovered in 1846.

Since then, astronomers on and off have believed they’ve seen evidence in the motions of the outer planets to hint at other planets lurking out there in the darkness. It was while searching for such a world that Illinois native Clyde Tombaugh found Pluto in 1930. However, it was later realized that Pluto was far too small to be causing any gravitational perturbations and in fact the perturbations themselves didn’t actually exist.

But this is where things get interesting, because it turned out that Pluto was actually simply the first in an entire class of tiny, distant solar system bodies called Kuiper Belt objects. Indeed, it was the discovery of more and more of these objects—some farther away and more distant than Pluto—that eventually caused Pluto to be reclassified as a dwarf planet.

Now, two astronomers from Caltech have published a paper arguing that the orbits of a handful of Kuiper Belt objects show evidence for an even larger body, about the size of Neptune, in the far reaches of the solar system. The reasoning is similar to that which led to the discovery of Neptune: it appears as though a large, massive object is affecting the orbits of these objects. Mathematical modeling indicates these observations could be explained by a ninth planet.

Of course this doesn’t mean that it’s there for sure. That’s how science works: observations provide evidence, and scientists offer a theory or hypothesis to explain it. A good hypothesis is one that can be tested. And that’s exactly what’s happening now: telescopes are being trained toward the outer reaches of the solar system to see if this posited body does indeed exist. If it does, it should be large enough to spot in very large telescopes, despite its enormous distance.

And if it is spotted, the total number of planets in the solar system will go back up to the number we learned in grade school.

This column originally appeared in the Kankakee Daily Journal.

Mason & Dixon

Mason and DixonMason and Dixon by Thomas Pynchon

My rating: 2 of 5 stars

The past is a different country, but in Pynchon’s work it might as well be a different planet– or at least a different reality. It is without a doubt someplace foreign, somewhere on the boundary of narrative and myth. Pynchon’s Mason & Dixon is, superficially, a historical fiction recounting the work of the British astronomers Charles Mason (1728–1786) and Jeremiah Dixon (1733–1779), who observed the 1761 transit of Venus across the Sun from the Cape of Good Hope but are better known today for measuring the colonial boundary known today as the Mason-Dixon line.

Mason & Dixon had been recommended to me because of its treatment of the history of astronomy. And there is indeed some great historical astronomy in here. I tagged a passage for my introductory astronomy class to read to illustrate that much of what we know as astronomy in the eighteenth century had nothing to do with probing the nature of celestial objects but was instead a means of measuring position and distances on the Earth’s surface. The primary characters are historical personages, and the narration frequently alludes to Mason’s journals. I wish, however, Pynchon would have explained in either a prefix or an afterward exactly what his sources were that formed the kernel of truth behind what was in many respects a shifting landscape of surreality.

On the skeleton of a historical framework, Pynchon rears a sprawling, phantasmagoric edifice that belies any sort of easy classification. Early on in the narrative the main characters meet a talking dog. Things get stranger from there, and their travels include encounters with a sentient, robotic duck, erotic Jesuit assassins, a Jewish Golem as large as a mountain, ghosts, giant vegetables, and signs of a pre-historic advanced civilization among ancient burial mounds. Most of the action takes place in the wilds of colonial America, where Pynchon uses his stream-of-consciousness approach to paint a wilderness of our own national legends and myths. It is a realm where what we think of as “real” history blends with history-that-could-have-been, or should have been, or was once imagined.

Pynchon’s writing style doesn’t make it any easier for the casual reader. The first thing to master is the eighteenth-century spellings and capitalizations, carried throughout the work. To be fair, once you’ve gotten used to this, it is no longer quite so noticeable and indeed deepens the feeling that you’re actually experiencing life as it was lived and thought over two hundred years ago. The following passage gives a good feeling for Pynchon’s stylistic approach. All of the ellipses are true to the text:

“What Machine is it,” young Cherrycoke later bade himself goodnight, “that bears us along so relentlessly? We go rattling thro’ another Day,– another Year,– as thro’ an empty Town without a Name, in the Midnight . . . we have but Memories of some Pause at the Pleasure-Spas of our younger Days, the Maidens, the Cards, the Claret,– we seek to extend our stay, but now a silent Functionary in dark Livery indicates it is time to re-board the Coach,and resume the Journey. Long before the Destination, moreover, shall this Machine come abruptly to a Stop . . . gather’d dense with Fear, shall we open the Door to confer with the Driver,. . . no Horses, . . . only the Machine, fading as we stand, and a Prairie of desperate Immensity. . . .”

What is harder to come to grips with is Pynchon’s casual treatment of chronology. Dialogue between characters describing a past event will move without warning into a firsthand narrative of said event with no transition. Pynchon’s approach of presenting the entire narrative as a story being told as a recollection by one of Mason and Dixon’s traveling companions in post-independence Philadelphia and switching back and forth between the narrative and description of what’s happening in this Philadelphia drawing room– frequent at first but falling away by the novel’s end– is also disconcerting. All of these scene and temporal shifts come on top of the reality-surreality disjunction that runs through the entire work, contributing to a sense vertigo that makes the whole thing– the primary extent of which chronicles the wanderings of the surveyors in America– feel like an extended fever dream.

It was beautiful in many places, and the weirdness and wonder of the story itself hung nicely with the practice of astronomy during this period, often portrayed in other sources as dull and unromantic. Pynchon plays with connections between carving lines of latitude across a wilderness and early modern (and lingering) beliefs in lines of energy and occult forces across landscapes. (Dixon, we learn, spent his student years not only learning how to mark surveying lines but also using them to fly across the English countryside on a broomstick by night.) But the sheer volume of the tale and its dizzying arabesques of flashback and fantasy and story within story grew (for me) wearing. Maybe Pynchon was making us feel the grind of Mason and Dixon across the unexplored countryside, driving a carefully calibrated visto across America’s “dreamtime,” but all of their eastward and westward peregrinations started to blend together in my own mind. What was I supposed to find in Mason’s melancholy and Dixon’s tales under those strange stars?

The strongest aspect of the story was the relationship between the two astronomer-surveyors, which is played to an excellent effect in the novel’s beginning, during their time at the Cape of Good Hope in South Africa, loses momentum in the bulk of the novel, and only reappears after they have returned to England at the novel’s conclusion. In between, for much of the work, I was as lost as Pynchon makes it feel Mason and Dixon were themselves, with only their lenses and latitudes to guide them. It’s a journey with no real destination– into the wilderness and back, and Pynchon shows you that not even the astronomers themselves were satisfied with it, leaving the reader with ghosts and narrative echoes: an imagined image of them continuing westward and Mason at long last returning (maybe?) from England to America to die.

“Meanwhile, there all of you are, accosting Strangers in Taverns, spilling forth your Sorrows, Gratis. One day, if it be his Will, God will seize and shake you like wayward daughters, and you will thenceforward give nothing away for free.”


Sometimes I’m a lazy stargazer. The first lunar eclipse of the year was April 15th. I wrote a post about it on the Adler Planetarium blog. But when it came to setting the alarm to get up in the middle of the night to view it, I was secretly relieved to go to bed to an overcast sky. William Herschel used to fall asleep reading astronomy books in bed. He, of course, eventually got out under the night sky. I often don’t get beyond the books in bed.

Which is perhaps one reason why the history of astronomy appeals to me. I admit it: sometimes I like reading about the discoveries made by observers throughout history more than I like sitting under a cold observatory dome alone at night. Books don’t cloud over. Manuscript collections usually can only be visited by day. If I fall asleep over my work, there’s no real fear– as there was for the Herschels– of falling off a telescope platform.

I do wish though I had caught the most recent lunar eclipse. They’re slow events, more sublime than spectacular. Not like a solar eclipse (which I have never witnessed, though 2017 is fast approaching).

The most recent display I curated at the Adler was of eclipse depictions throughout history. These are all from the works on paper collection at the Adler (maps, diagrams, pictures, things that can be hung on a wall). The images really are quite nice, though the pictures I took don’t do them justice. (The gallery has subdued lighting, and a camera flash would have only created glare.) My favorite is of a broadside poster printed in the 1760s in England providing information on an upcoming solar eclipse. This would have been hung in a public place and is an early form of public science education, explaining what causes the eclipse and what the public could expect to see.

There’s a diagram from a medieval textbook as well, illustrating how the shape of the Earth can be deduced from the shape of the shadow during a lunar eclipse, and a few other images.

If you’re in Chicago, stop by the planetarium and take a look.




And this is me with my best (and unfortunately completely unintentional) mad scientist face. I presented a poster on the Dioptrice project, a database of pre-1775 refracting telescopes that I’ve been working on as a research assistant for the past few years at the Adler Planetarium as part of my graduate program in the history and philosophy of science at Notre Dame. I didn’t win the student poster presentation, but I did garner some good publicity.

A writer for ScienceNOW, the online publication of the AAAS, picked up the story and wrote up a summary of the Dioptrice project you can view here.

I got a call a few days later from another writer, this time for the science news site motherboard.tv, who wanted to do a piece on the project. His story is here.

Essays from the Edinburgh and Quarterly Reviews

Essays from the Edinburgh and Quarterly Reviews by John F.W. Herschel

My rating: 3 of 5 stars

Historians of Victorian science often speak about a common intellectual context that fragmented in the latter half of the nineteenth century. The growth of scientific disciplines, the specialization of fields, and the proliferation of specialized journals made it difficult to stay abreast of all developments in science or maintain a synthetic view of the entire field. What’s more, as science became professionalized, science writing moved to periodicals and publications written specifically for scientists. There arose a divide between science and popular writings or cultural criticism that largely remains to this day.

The Edinburgh and Quarterly Reviews represented what popular, high-brow literature looked like before these changes took place. In their glory days at the beginning of the nineteenth century, the Reviews were a place to discuss politics and culture– including science. This collection of essays and poems by John Herschel illustrates the place that science held in popular culture. Though largely forgotten today, Herschel was arguably the leading popular figure in science in the generation before Einstein. In these essays he discusses everything from Laplace’s celestial mechanics to Whewell’s philosophy of science to Quetelet’s statistics. What’s fascinating is the detailed (though largely non-mathematical) treatment he goes into for a “popular” audience. These essays, important for historians of Victorian society in general and astronomy in particular, are recommended reading (or, more likely, skimming) for anyone who is interested in the sort of treatment science was given in the Victorian period for the general, educated reader.

The Sun Kings

The Sun Kings: The Unexpected Tragedy of Richard Carrington and the Tale of How Modern Astronomy BeganThe Sun Kings: The Unexpected Tragedy of Richard Carrington and the Tale of How Modern Astronomy Began by Stuart Clark

My rating: 3 of 5 stars

I don’t get to read a lot of popularizations in the course of my research on nineteenth-century astronomy, so when this one came across my desk I was on the one hand excited about a change of pace (“captivating, fast-paced” says Dava Sobel on the cover) and on the other figuring I’d be skimming much of it and rolling my eyes a lot. I tend to do this with books that have long and overly-dramatic subtitles like “The Unexpected Tragedy of Richard Carrington and the Tale of How Modern Astronomy Began.”

I was half right. I did indeed do a lot of skimming, but I also did much less eye-rolling than I anticipated. Clark weaves a compelling tale, even if you don’t consider an understanding of the dynamic Earth-Sun relationship (think SOHO and Spaceweather.com) to be the beginning of modern astronomy. (I don’t.) The book is a bit less than the subtitle makes it out to be, as I’m still not  sure what Carrington’s “unexpected tragedy” was or how it relates to the scientific quest to understand the Sun’s interaction with the Earth, but it was a quite enjoyable romp through the world of Victorian astronomy.

Because it’s such an interesting place, Victorian astronomy, you almost can’t help to tell a compelling story if you go into it with some historical grounding and a flair for narrative. Clark treats one aspect of what was happening during this period: the development of solar astronomy. At the beginning of the 1800s, no one had any idea what the structure of the Sun was or how it generated its energy. One prevailing theory was that it was composed of a solid (and possibly inhabited!) core surrounded by a luminous atmosphere. Sunspots were rifts in this solar atmosphere. Clarke recounts how a series of dedicated astronomers– both professional and amateur– deduced a link between sunspots, the solar cycle, and effects on the Earth such as magnetic disturbances and auroral activity. Carrington is simply one of a cast that includes many important astronomers from this period, though Carrington’s drive and complex personal life, as well as his final demise (and this is likely the tragedy referred to in the subtitle, though seemingly unrelated to solar physics) make him an especially compelling figure.

Even if you’re not interested in the ins and outs of the interaction between the Sun and the Earth’s magnetic field or the advances in spectroscopy and photography that made the discoveries documented in this book possible, it’s the historical characters like Carrington who make studies in Victorian science so readable. Carrington was one of many amateur astronomers during this period who made their fortune in business (in Carrington’s case a brewery) and then used this wealth to build elaborate personal observatories where they could pursue astronomy as a hobby. Carrington devoted himself to solar astronomy and became a recognized authority on the subject. Besides him though, the pages are filled with other characters equally interesting: Airy, the Astronomer Royal and the story’s villain, storming about at Greenwich pursuing mathematical accuracy and largely dismissive of the new physical astronomy; de la Rue laboring in Spain to photograph the Sun’s atmosphere for the first time during a solar eclipse; Maunder taking up Carrington’s work after Carrington’s death and marrying the young mathematician hired to aid his calculations. Interesting characters pursuing interesting work. Maybe exaggerated or characatured just a bit, but they all come in and out of the story so quickly and in such succession that Clark can’t be blamed much for emphasizing their most interesting features.

It was an exciting time in astronomy, and Clark captures this. I’ll keep it on the shelf, because it would be ideal book report material for an undergraduate astronomy course. A historian will find Clark’s lack of careful documentation maddening and his rhetoric at times excessive or overblown, but a student (or reader) with a passing interest in the history of astronomy might find it a door to a truly remarkable period in history.



One of the largest and longest-running projects I’ve been working on as part of my research fellowship at Notre Dame and the Adler Planetarium has been Dioptrice, a database of surviving pre-1775 refracting telescopes. The brainchild of the former chief curator at the Adler, Dioptrice is the first step toward a richer history of the telescope: its origins, evolution, and diffusion as well as popular perceptions of the instrument in works of art and early books and manuscripts. The principle investigators of the project, which is funded by NSF and NEH grants, travel the world looking for early telescopes in museums and private collections. They analyze and photograph them and then send the data to me, where I add it to the database. I also scour catalogues and websites, initiate contact with additional collections, and search the rare book collection at the Adler for early telescope images. All of this goes into the database, which has been slowly building for the past few years.

Now it’s ready to go public. Information on hundreds of telescopes, fully searchable by year, type, maker, country of origin, and just about every other category you can think of. All hosted online in a sleek website designed by Parallactic Consulting but curated by yours truly. If you’re interested in the history of the telescope as art, artifact, or instrument, feel free to look around. If you know of telescopes that should be hosted here, let me know.

Have fun: www.dioptrice.com.


Update: I presented a poster on Dioptrice at the AAAS meeting in Chicago yesterday. ScienceNOW, the online AAAS science magazine, just published an article on the database, and I was featured as part of the #scienceWOW video series talking about William Herschel. (You can see all the videos, including one by Alan Alda, here.)

Calendar of the Correspondence of Sir John Herschel

A Calendar Of The Correspondence Of Sir John HerschelA Calendar Of The Correspondence Of Sir John Herschel by Michael J. Crowe

My rating: 3 of 5 stars

John Herschel was the most famous scientist you never heard of. His name may sound familiar (especially if you’ve spent much time around me), but if so you’re likely thinking of his father, the astronomer famous for discovering the planet Uranus. Yet during his lifetime John Herschel, whose life and career spanned most of the nineteenth century, was Britain’s leading scientist (though the term itself is a bit anachronistic here) and a prime player in the international scientific community. I tell people he was the Stephen Hawking of the nineteenth century: an astronomer himself and the person people thought of when they envisioned the epitome of the scientific life. His generation considered him second to Newton in English science, so much so that he was buried next to the famous physicist in Westminster Abbey upon his death.

So why has no one heard of him today? There are lots of likely reasons. Though his career spanned decades, he was the last of the natural philosophers, the scientists who could still expect to have a mastery of all scientific fields. In astronomy, he was the first (and perhaps the only) to closely survey the entire northern and southern skies with a large optical telescope. But despite his influence he had no single large discovery (like his father’s planet), and his work was quickly overshadowed by the developments of spectroscopy and photography. In mathematics, he is largely the reason we use the Continental form of calculus instead of the Newtonian fluxions that held sway in England until the early 1800s, but the history of mathematical analysis doesn’t make great cover. He did important work in optics, chemistry, and photography as well, before they were considered separate fields. He coined the phrases snapshot, negative, and positive. His very omnicompetence may have helped efface his memory. He doesn’t have one specific theory or field of speciality to attach to him, like Maxwell or Darwin.

This breadth also contributes to another aspect of Herschel’s current anonymity: lack of a good biography. An adequate biography of Herschel would be a huge undertaking. The only attempt so far is a book-length sketch by a German librarian, which has been translated into English (Gunther Buttmann’s The Shadow of the Telescope). Herschel is starting to get more treatment though. He features prominently in Laura Snyder’s The Philosophical Breakfast Club and Richard Holmes’ Age of Wonder. In both of these however, Herschel himself is not the primary focus.

Several years ago Dr. Michael Crowe, a scholar on my dissertation committee, decided he would attempt a Herschel biography. What he realized very quickly though was that the amount of material that needed to be processed for such a project was immense. Correspondence to and from Herschel alone (not to mention his published works and his journals) amounted to more than 14,000 letters scattered in repositories, libraries, and archives all over the world. The first task would be to assemble and organize this correspondence, and the results (after a decade of work involving dozens of graduate students) was the massive Calendar of the Correspondence of Sir John Herschel.

This is not a book to be read straight through (unless you’re writing your dissertation on Herschel). It is truly massive, for one thing, weighing in at over 700 pages. And the content is not narrative but instead chronological summaries of all of Herschel’s correspondence. Every letter (known at the time) that he wrote or received has been read, dated, and summarized. And then indexed, which is perhaps the most useful thing of all. Because Herschel really was at the center of an immense network of scientists, and if you are interested in any aspect of what might loosely be termed Victorian science (and why wouldn’t you be, because this is the age of steam, electricity, exploration– science becoming the science we know today) you’re likely to find that Herschel corresponded with someone about it. Pretty much every big name (and several smaller ones) in the history of nineteenth-century science makes an appearance.

For a Herschel scholar, this is an absolutely essential resource. Besides a complete guide to his letters, Crowe also includes very large and very useful appendices listing all of Herschel’s published works as well as a bibliography of secondary works on Herschel up to the time of publishing (and while there is still no book-length treatment of Herschel’s life, the huge amount of papers and essays written about him shows his enduring influence on a wide range of fields). Though the book is currently out of print, the information entailed is available in an even more useful form, fully searchable and online, as a database hosted by the Adler Planetarium.

Venture forth: http://historydb.adlerplanetarium.org.

Lunar Frontiers


For the past two-and-a-half years I have served as a research and curatorial intern at the Adler Planetarium & Astronomy Museum as part of my fellowship at the University of Notre Dame. Much of my work there has involved creating and curating a database of surviving pre-1775 refracting telescopes from around the world. Lately I have had the opportunity to help select artifacts and write up descriptions for some temporary exhibits. This was my first, part of a display on lunar maps and globes.

I was surprised how challenging it was to present the information on these objects via concise captions that were accessible yet accurate and retained the details that made them such interesting pieces. This particular display contained three lunar globes from the Adler’s collection as well as a lunar atlas and telescope. I’ve included captions and images of my favorite objects below.

DSCF3900 DSCF3906

DSCF3902 DSCF3908

This last globe offered a mystery, as a previous owner had affixed unlabeled colored markers at various locations. A bit of homework indicated they corresponded with various lunar landings and helped estimate the globe’s date. If you’re in Chicago, head to the Adler and check them out!