by Mary Hrovat

Photograph of Mayall Telescope and others on Kitt PeakWhen I returned to school after my first marriage ended, I had to decide what to study. I’d been working toward a degree in history when I dropped out of a community college to get married, but I’d always been drawn to astronomy. One of the reasons I chose astronomy over history, or any other option, was that I felt that astronomy contained many of the other things I was interested in. To put it another way, I thought that if I didn’t study astronomy, I would regret it, but if I did study it, I wouldn’t necessarily lose touch with the other things I was interested in because they were all part of astronomy, in one way or another.

My degree is actually in astrophysics, and obviously it involved a lot of physics and mathematics. To see how the universe works, you have to understand gravitation, nuclear fusion, thermodynamics, atomic physics, and much more. In addition, to use and design telescopes and detectors, you need to know about optics, electronics, and materials science. Although I started out with very little background in math, I wound up with a minor in mathematics. By the time I had taken all the math classes required for the degree, and a fourth semester of calculus (which I hoped would help me understand my physics classes better), I was only three credits away from a math minor, so I took a class in linear algebra.

Astronomy also has obvious links to chemistry and geology. The story of the universe is, from one viewpoint, the story of chemical evolution, the development of more complex chemical elements as stars turned hydrogen and helium into more complex elements through nucleosynthesis. To study planets and moons, we can sometimes apply what we know about the rocks and weather and geological processes of Earth. Geology also comes into play in other ways. For example, one piece of evidence for the dinosaur-killing asteroid that struck Earth around 65 million years ago is a thin layer of iridium in Earth’s crust.

In addition, some sedimentary rocks on Earth provide a record of long-ago tides; specifically, layers in the rocks reveal the intervals between certain types of tides, and these intervals in turn reflect the distance between Earth and the moon. This distance is very slowly increasing, and as it does, the day is very slowly getting longer. By examining the tidal records in rocks of different ages, it’s possible to determine the Earth–moon distance, and thus the length of the day, at the time the sediments were deposited. Four groups of rocks in the US with ages ranging from 305 million years to 900 million years have been used for this purpose, and much older rocks have been studied in other parts of the world. The tidal data from the oldest of these rocks even has implications for the origins of life on Earth.


I had no idea of that particular connection between astronomy, geology, and biology when I began my astronomy degree (in fact, some of the work hadn’t been done then). However, astrobiology and biochemistry are crucial to understanding whether life is unique to Earth or might exist elsewhere, and if it does exist on other planets, what it might be like. These questions are obviously important for philosophy and religion, and the history of that particular connection is especially rich and complex.

Astronomy has a history of discoveries that broadened or overturned our view of the universe and our place in it. This was an especially giddy prospect for me as a young student because my timeline had been thoroughly shaped by my parents’ religious views, and I knew little about the great age of Earth and the history of the universe. My view of human history changed when I was able to put it in the context of the entire cosmos. In addition, the mythology and folklore of many different civilizations are relevant to astronomy when you consider the stories and beliefs associated with the constellations and planets, not to mention the names of objects in the night sky and their treatment in art and literature.

To look at something like a research telescope is to take in much more than just the use of the telescope as an astronomical tool. The presence of a telescope at a mountain observatory calls to mind not just astronomy and optics, but also atmospheric science, various types of technology, politics, and even environmental and cultural considerations.


Of course, this is not an essay about how uniquely broad the study of astronomy is. Although astronomy is a historical science and inherently presents a broad vision of how things got to be this way, geology and biology are also historical sciences with that kind of scope. And every science and every type of human activity has a history that’s connected to larger historical events, sometimes in surprising ways. (I’m currently reading a book about the role trees have played in American history, for example, and I just read about how the logging of Sitka spruce in the Pacific Northwest was crucial to production of Allied airplanes in World War I.)

Furthermore, every human pursuit relies on a broad base of knowledge. To take just a few examples, botany, gardening, and wine-making all open doors onto soil chemistry, geology, entomology, the study of various microorganisms, genetics, and even, arguably, psychology. To learn a craft, you must learn about the materials it uses, the tools and their development, history, maybe aesthetics, possibly some chemistry or physics or mathematics. The outline of human knowledge inherent in a high school curriculum or a university’s organizational structure is a simplified map of a complex territory.

When I was maybe 10 or 11, I tried to confirm a hunch about the complex structure that lay within an encyclopedia’s entries (which were arranged alphabetically, in the simplest and least revealing arrangement). For this project, I used a set of children’s encyclopedias, the kind you bought a volume at a time at the grocery store. I started with one entry; it may have been “calendar” or “time.” I wrote down all of the “also see” entries listed at the end of that entry, and then I started going to each of them in turn and listing their “also see” entries.

As I remember it, I had the idea that I would eventually be led to every single article in the entire set. I got bogged down when my record-keeping became chaotic, and I eventually abandoned the project. (My tools were a pencil and notebook paper, and it was easy to lose track of where I was.) There’s no telling if I would in fact have visited every entry if I’d stuck with it. I can be pretty sure, though, that I would have followed a different but equally rich path if I’d started with “dinosaur,” say, or “rocket,” or “ocean.”


The Knowledge Web is an interactive tool that’s being designed to present numerous entry points to learning that will lead people on journeys something like the one I attempted with that set of encyclopedias. It’s the brain child of James Burke, a science historian whose work includes several excellent documentary series on the history of science and technology. These include Connections, which first aired in 1978 and showed how various inventions and discoveries arose from surprising or serendipitous connections between the facts, materials, and social conditions that were known or prevailed at the time.

I heard Burke talk about this project 10 or 15 years ago, and I was struck by his idea that people would be able enter the Knowledge Web at any point that particularly interested them, whether that was race cars or birds or jazz, and then find other fields opening up to them as they learned more. This seemed to be the ultimate development of something I’d observed in the years after I got my degree: Other people felt about their academic subjects or interests pretty much as I felt about astronomy. They were drawn to a topic by love or affinity and found that it contained more or less everything else there was to know.

For example, sometime in the 1990s, I heard a music educator on the NPR show Performance Today who said that for her, music was the broadest subject. If you were teaching kids about music, you could approach it through history, put it in the context of other arts, look at it in terms of the physics of sound or the principles that determine how musical instruments work, and on and on.

Emily Kimbrough, in her book Forever Old, Forever New, described a conversation she had with an archeologist in Greece, who explained the importance of understanding geological strata in order to grasp the timeline of a site. She was surprised to learn that archeologists had to know that much about geology, and he told her that as far as he was concerned, his field involved the study of almost every other subject, and that’s what made it interesting to him. Lawrence Osborne, in The Accidental Connoisseur, notes that the study of wine is appealing because it involves so many other areas: geography, geology, history, cooking, anthropology.

Ralph Waldo Emerson put it this way: “All things in the universe arrange themselves to each person anew, according to his ruling love.”


The photograph of Kitt Peak in southeastern Arizona (looking north; the tallest building houses the Mayall 4-Meter Telescope) is the work of Patrick Alexander.

You can see more of my writing at