Science and the Educated American: A Core Component of Liberal Education

Chapter 7: Learning Astronomy through Writing

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Jerrold Meinwald and John G. Hildebrand
Science in the Liberal Arts Curriculum

Martha P. Haynes

Most astronomy courses at colleges and universities in the United States are geared toward the non-science major and are often used to fulfill general science distribution requirements. Many students have some basic curiosity about the universe around them, which makes astronomy a popular introductory subject. But enrollment in introductory astronomy courses may be these students’ only exposure to science at the college level. Under these circumstances, science courses must emphasize the scientific method and the process of scientific research and discovery as much as factual content. In the Google Age, teaching how to pose a scientific question may be more important than teaching how to find its answer.

Many non-science majors seem resistant to problem solving and quantitative approaches. Some claim boredom when faced with the traditional science class. An alternative approach designed to provide these students comfort is to immerse them in familiar surroundings—essay writing, some of it creative— while still challenging them to think quantitatively and scientifically. Cornell University’s Astronomy 2201 course, “Our Home in the Universe,” is designed specifically to engage those students who enjoy writing, especially those who are stimulated by the chance to express their creativity while being exposed to the scientific concepts required to meet the content expectations of distribution requirements.


Like many colleges and universities in the United States, Cornell University requires most of its undergraduate students to enroll in courses that are designed to improve their writing skills. In the College of Arts and Sciences, students must complete two freshman writing seminars; students with Advanced Placement credit in English literature can opt out of one class, but not both.

Other colleges require only one writing seminar, but faculty can assume that all students will have had some college-level instruction in the art and practice of writing. At Cornell, the freshman writing seminars are taught not only in the English department but across the academic disciplines, often by advanced graduate students under faculty supervision. Recently, three of my graduate students have taught the freshman writing seminar Astronomy 1109, which fully meets the writing distribution requirements while also giving students a broad introduction to astronomy and cosmology. All three of these young educators are excellent scientists as well as dedicated teachers, and each valued the opportunity to gain experience leading a composition course. The demand for freshman writing seminars taught in the sciences is high. One year, 250 incoming freshmen tried to elect Astronomy 1109, but like all freshman seminars, its enrollment was capped at 18.

For many years, Cornell has emphasized the importance of writing and fostered its inclusion across the curriculum through the John S. Knight Institute for Writing in the Disciplines. Among the Knight Institute’s activities, the Writing in the Majors (WIM) program encourages faculty to incorporate writing into discipline-oriented courses where writing is not the tradition. In the humanities, written essays and course papers are standard course requirements. Science classes, however, tend to focus on problem sets and short-answer or multiple-choice tests. For the student who finds writing an essay to be natural —even enjoyable—a science class organized around verbal expression and the synthesis of acquired knowledge, rather than repeated testing of that knowledge, will seem more familiar and user-friendly. More important, such students are likely to be just as successful as in more traditional science courses. At Cornell, the goal is to teach non-science majors in a way they will find comfortable, but without reducing the level of science content. Under the auspices of the WIM program, Cornell now offers several one-semester astronomy courses— including Astro2201, which I teach—intended for students who like to write. Most enrollees use the class to fulfill a science distribution requirement in their undergraduate college.


Most astronomy departments offer large lecture-based survey courses to hundreds of students. The faculty who teach these classes are often the most gifted and high-profile lecturers. The course material usually closely tracks the material in the adopted textbook; the written work consists of problem-oriented homework, multiple-choice or short-answer tests, and, possibly, lab exercises; and the design of the course reflects an approach to science education with which most students are already familiar. Such courses are generally predictable to students, who need only study (memorize) the material covered in the textbook. Despite the high student-to-instructor ratio, grading students in these courses is typically quick and straightforward. A common occurrence, however, is for class attendance to flag, though the recent introduction of in-class interactions and the use of “clickers” have been successful in alleviating problems of unnecessary absence.

By contrast, in a smaller class the professor will know all of his or her students, and assignments will require them to synthesize material presented in class. At Cornell, Astro2201 is promoted as a more intimate and user-friendly way to study astronomy, at least among those students for whom writing comes naturally. To catch students’ attention, the course syllabus focuses on a handful of popular themes: the development of astronomical thinking, black holes, dark matter, the life and death of stars, and the history of the universe. A complementary course taught by my colleagues centers on the solar system. Their curriculum covers water on other planets, the diversity of planetary systems, the search for exoplanets, and killer asteroids, but still incorporates more traditional topics—from general physics concepts such as Newton’s laws and the electromagnetic spectrum to astronomical topics such as stellar evolution and nucleosynthesis. Not all students will want to enroll in a class that emphasizes writing, but for a particular segment of the undergraduate population, such a course framework holds a strong attraction.


The advantage of a course without strictly required content is that it can be designed around those topics of greatest interest to students. In order to meet our college’s expectations for the content of a science class, we strive to strike a balance between a few specific themes (such as black holes and cosmology) and adequate discussion of the fundamental physical laws and astrophysical concepts. In this way, students master a broad sweep of introductory astronomy and astrophysics, albeit without covering all possible topics. Because Astro2201 is often taught as two separate sections by different instructors who try to coordinate activities (in order to avoid questions about equality of rigor, required work, and so on), we have attempted to maintain some semblance of generality while also maintaining the individuality of the syllabus relative to other courses the department offers. As a result, Astro2201 is quite different in scope and depth from the more traditional survey course.

Writing Assignments

Our approach is based on the premise that students required to write about science will be forced to develop scientific knowledge and understanding in order to complete their writing assignments. Over the years, we have experimented not only with the nature of the assignments but with their frequency and length. We have found that regular (almost weekly) assignments are the best way to maintain student engagement. The shorter assignments are a maximum of 500 words in length. Longer papers, including a final paper, are required at three- to four-week intervals and vary in length from 900 to 1,500 words (the final). We have found that longer papers produce less originality and more regurgitation of books and websites. Therefore, we try to focus students’ papers on limited topics and the discussion of issues that are not entirely new; assignments to a large extent draw on classroom content and discussion, but might ask students to apply their knowledge in a different context or to address a different audience. Some assignments are written as memos or briefings in a hypothetical work situation. Others call for explanations written for children or in response to questions from former teachers. In each case, the student is asked to assume a well-defined role of a writer addressing a particular audience. This focus helps students communicate their mastery of science content without becoming bogged down or distracted by the writing itself.

Making the Context and Audience Clear

Designing assignments for a writing-based science class requires establishing a balance between testing the acquisition of knowledge and fostering creativity in writing. The modern information age has given rise to a practical challenge: students today have trivially easy access to huge quantities of written words of widely varying scientific quality. Constructing assignments that are educational, somewhat fun, and not easily answered by Internet search engines becomes the trick. Our approach is to exploit a somewhat extraordinary scenario for individual assignments and to define specifically and carefully that context and the intended audience. Placing students in an ancient era, for example, forces them to think about what scientific knowledge was not available in earlier times. In one assignment, we ask students to imagine

The year is 1280 A.D. You are a young scholar in the court of Alfonso X, king of Castile and Leon, also known as Alfonso the Wise. An avid astronomer, you spend your nights viewing the skies and your days reading whatever histories of observations and discourses on cosmological thinking that you can find. You have read all the ancient Greeks and of course know Ptolemy’s “Almagest” practically by heart. You are a member of the team compiling the planetary tables “Tablas” from observations being conducted at Toledo and from various accumulated astronomical records, particularly ones from the Arab world.

The assignment then places the writer in the role of Alfonso’s great nephew; it mentions that the king has been curious about celestial events since he witnessed a total solar eclipse during a “vacation in Madrid when he was your age.” The assignment notes that a total solar eclipse was visible from Madrid in 1239 A.D. but that the student cannot be sure if Alfonso actually saw it. He or she can, however, assume that Alfonso is familiar with the Ptolemaic explanation for the motions of the celestial bodies. More precisely, the student must imagine that:

Lately, you’ve come to the conclusion that the Ptolemaic system is wrong and that the heliocentric universe makes more sense. Because you realize that such ideas might be viewed as heretical by your more senior colleagues, you decide to write your thoughts about the nature of the universe in a letter to Great Uncle Alfonso.

Keeping in mind that your letter comes more than 200 years before Copernicus and that all you have available are the records of naked-eye observations and the writings of the ancient Greeks through Ptolemy, make your letter as scientifically convincing as possible. Also be sure to summarize the basic tenets of each viewpoint as well as the pro’s and con’s, since Alfonso may have forgotten the details.

Your quill will run out of ink at about 1000 words. Because Alfonso’s eyesight isn’t as sharp as it used to be, please be sure to double space the letter.

By setting a word limit, we force students to concentrate on the information that is relevant and necessary to respond to the prompt. This assignment requires students to understand the logic behind the heliocentric and geocentric universe concepts; it also raises for their consideration how scientific discovery leads to scientific understanding. Some students immerse themselves in the role of the writer, producing enjoyable letters to “Uncle Alfonso.” (Modern word processing packages even allow students to print their assignments as if they were written with a quill.)

Another character used in Astro2201 assignments grew out of my personal experience. Some years ago, I spent several months of a sabbatical working in Washington, D.C., as the interim president of Associated Universities, Inc., a nonprofit corporation that manages national astronomy research facilities funded by the National Science Foundation. During that period, I visited a number of congressional offices and met with staff to discuss the programs under the corporation’s purview. In every one of those offices, one of the staff members was a Cornell graduate, albeit rarely in a scientific discipline. That experience prompted me to realize that some of the articulate—if occasionally scruffy—young people who enroll in Astro2201 might end up in a congressional office and, more important, that their appreciation of science and scientific research may be rooted in their Astro2201 experience. From my encounters in Washington emerged a character described as a staff adviser to “Senator Wisdom, of Great Prairie State, an influential member of the Senate Appropriations Committee’s Subcommittee on Commerce, Justice, Science, and Related Agencies,” who was introduced as an ongoing player in Astro2201 assignments. In almost every class, at least one student harbors political ambitions and therefore identifies with this story.


Over the years, we have experimented with assignments that require at least one round of revisions based on the professors’ comments. We generally choose this approach with a conceptually difficult assignment that allows us to use the revision process as a way of insisting that students master the concepts. Our favorite of these assignments is a briefing to Senator Wisdom in which the student/staffer is tasked with summarizing and providing the context for large astronomy facilities—either in existence or under construction—that receive funding from the federal government. For example, we recently asked students to explain the scientific rationale for, and technical differences between, the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA). Why is one destined for space and the other for the ground? Why could ALMA not be built in Great Prairie State? Are any of the senator’s constituents interested in these projects? This context requires that students appreciate the different capabilities of actual astronomical instrumentation, the technical challenges of building telescopes to operate in different portions of the electromagnetic spectrum, and the scientific questions that can be addressed by different instruments. Both the first draft and a revision based on our comments receive grades, and we carefully point out that our expectations for precision and clarity increase significantly for the revised version. Our comments often address students’ use of terms they clearly do not understand. The process of revision forces them to explain concepts in their own words, something they generally cannot do unless they fully understand those concepts. We thus use revision to push students’ scientific thinking beyond what they might be able to demonstrate after only a single round of essay development.

Group Assignments

In every second or third class, we spend part of the period engaged in group activity: working through a problem, interpreting the information contained in an image, discussing an astrophysical circumstance, or designing and conducting a simple experiment. Each student retains his or her own copy of the exercise; the groups hand in the result of work done in class; and work not completed in class is expected to be finished outside of class. Group exercises are not graded, but problems posed in them often reappear in the essay assignments. The exercises are not elaborate, require almost no equipment, and are intended mainly to compel students to apply, in an active and immediate way, the most important formulas, facts, and concepts covered in the lecture. Group exercises call on students to develop their own identification and understanding of critical concepts and give professors an opportunity to observe which aspects are a struggle for students. Because the discussions and in-class exercises in many cases cannot be re-created, we state at the beginning of the semester that attendance is required. Missed in-class assignments cannot be done outside of class, but they can be excused for valid reasons. While we do not keep a regular list of attendance, keeping track of who is present is easy. Regular, unannounced in-class exercises that count toward the final grade provide a strong incentive to attend class.

The Portfolio

Each assignment is geared toward the understanding of specific concepts covered in the preceding classes. Some assignments build on others completed earlier in the semester, and in order to emphasize continuity, we require that students keep a portfolio of their graded work as well as the shorter group exercises done in class. The portfolio is collected twice during the semester for review and helps earn points for the conscientious student who attends class and participates. Because we have found (surprisingly) that many students do not seem predisposed to note-taking, the accumulation of in-class work in the portfolio reinforces the need for recording information in the absence of having a formal laboratory component—that is, to some extent, the portfolio serves as a lab notebook. Additionally, it provides a useful way to organize and give weight to the in-class assignments, especially those we refer to some weeks after they are initially completed.

Appreciating Peer Review

The awarding of telescope time, the funding of grants, and the evaluation of submitted manuscripts make astronomers appreciate the value of peer review. Therefore, we give students an opportunity to explore how peer review works and also to experience the grading process themselves. We have them read, rank, comment on, and assign grades to a collection of four short essays of varying quality completed by their classmates earlier in the semester. Because we do not want students to read their own papers, we ask them to read papers written by students in a different section of Astro2201. (If we did not offer multiple sections of the course, we would assign different collections of papers to different groups within a class, ensuring that no correlation existed between a group’s members and authorship of the papers the group was assigned to review.) Although they dislike ranking the papers and assigning grades, students are, frankly, often more critical than we are. The exercise teaches them about the process of peer review; it also gives them a better appreciation of how difficult grading is and hence wins us quite a bit of sympathy.

The Graduate Teaching Assistant Experience

Class assignments are read by the graduate teaching assistant (TA) and (usually) the faculty member. The TA receives special training in how to read, comment on, and grade writing assignments. When graded work is returned to students, the graduate assistant discusses during the class period the correct answers and comments generally on the exposition. Written comments are provided on each paper so that students can reflect on how to improve as the semester progresses. The TAs are strongly encouraged to enroll concurrently in the graduate-level Writing in the Majors Seminar (WRIT 7101) taught by Keith Hjortshoj, who has been director of the WIM program since 1992. Through this seminar, our astronomy graduate students receive formal instruction in the theory of teaching writing and benefit from the years of experience that the staff of Cornell’s writing program can offer them.

Grades and Grading

Unfortunately, students object when they do not understand how each point is assigned. Explaining the grading scheme for structured tests (such as multiple choice) is much easier than doing so for written work (as is grading such tests). In Astro2201, grades are based on the accumulation of points awarded for the quality of a series of writing assignments, as well as for class attendance and participation. The maximum point award for each assignment depends on its length and difficulty. By reviewing the current point distribution at various times during the semester, we are able to give students a review of basic statistics, such as the meaning of mean, median, and standard deviation. Because Cornell publishes the median grade awarded in each class, we presume they already know what to expect.

We devise writing assignments that require clear answers, then establish and stick to criteria that can be tied to a quantitative grading scale. This method is important. Creativity and exposition should count, but scientific content must be emphasized. A beautifully written essay that is weak in scientific content should receive a low grade—as should a poorly written essay that is scientifically strong. Each writing assignment must receive a comment that is specific and personal enough that each student can understand how his or her grade was assigned and what he or she needs to do to improve the assignment.

An important practical aspect of designing writing assignments is providing clear guidelines about the grading scheme. Students are more comfortable if they know whether they have accomplished the goal. One of my favorite contexts for assignments illustrates this approach. The assignment asks the student to identify errors in the scientific basis of a screenplay:

In this assignment, you are a movie script editor in Hollywood. Your producer has asked you to proofread the screenplay of the next megahit on the adventures of Ithaca Jones, the famous adventurer-academic from Cornell University. The story opens as follows:

Opening scene. In his office, Ithaca Jones studies an ancient papyrus found accidentally folded within a book at a used book store in Dryden, NY, and hence called the “Dryden Codex.” The document has a map of the necropolis of Giza, in Egypt, and hieroglyphs which IJ deciphers with admirable ease. The camera zooms on the mystified but handsome face of IJ, as he says: “The millennium eclipse . . . the mask of Khufu!” IJ grabs his inseparable hat and rushes across campus to the office of his astronomer friend. From him, he learns that a solar eclipse is due in northern Africa in late March of the year 2009. Scene cuts on IJ’s emphatic exclamation: “Yes!!”

The remainder of the assignment describes a series of events that take place in Giza and elsewhere on the day of the supposed solar eclipse. The instructions for the assignment are then given:

Having taken Astro2201, you of course notice that this script draft is astronomically full of holes. Several (at least six) major problems of general astronomical nature could seriously embarrass its makers and mar the show. You thus decide to inform the producer, and do so concisely but fully, by means of a memo of 500 words or less in which you explain the reasons behind each problem you identify. As far as we know, a solar eclipse will not take place in northern Africa on March 22, 2009. This should not be considered an error, but rather artistic license.

Students who identify fewer than six problems with the astronomical content of the screenplay are awarded fewer points for the assignment. Because students are asked to explain the background of each problem, they must propose an alternative. Asking them to limit their memo to five hundred words helps teach them to use words judiciously and to confine their responses to relevant information rather than wandering off subject. Because the memo format is repeated in several other assignments throughout the semester, we have opportunities to comment on how successfully students meet the requirements of a given format. We generally see significant improvement in students’ writing over the course of the semester.

A particular challenge of the writing class in a nontraditional discipline is to avoid having the writing aspects interfere with the acquisition of curricular content. Because of the somewhat unconventional nature of the writing assignments, some students initially have difficulty understanding what we are asking of them. Common errors early in the semester include deviating from the topic, bringing in irrelevant information, using terminology that the audience would not (and probably the writer does not) understand, and failing to provide enough specificity. However, these flaws are usually quickly overcome once the student understands what we are looking for.


Not every lesson plan or course syllabus for Astro2201 has proved equally effective, and we have learned on the job what works and what does not. While “one size does not fit all,” some of the lessons we have learned may be of use to others considering a similar course.

Teach through Images

Astronomy is a science principally practiced by observing the night sky, usually with powerful telescopes. Images of astronomical objects wind up scattered across everyday life: we have a line of automobiles called “Saturn,” a candy bar called “Milky Way,” a cleaner called “Comet,” and a professional soccer team called the “Galaxy.” Children’s bedroom ceilings are adorned with glow-in-the-dark stars. My own very unscientific mother bought me a bedspread depicting the moon, stars, and Saturn. Today’s images from the Hubble Space Telescope or the Very Large Array may be more detailed and colorful than images produced by earlier telescopes, but even older ones can still be intriguing and even beautiful. The scientific objective of interpreting astronomical images involves deducing information about the physical characteristics and conditions of the object, its place within the cosmic hierarchy, and its evolutionary history. Encouraging students to think beyond the mere appearance of celestial objects, to consider the origin of their colors and structure and the physical processes that produce the radiation we detect in an image, is a good way to engage them in the methods of astronomy and the tools astronomers use to deduce information about the cosmos.

Encourage Interaction Early and Often

To facilitate in-class discussions and group activities, enrollment in Astro2201 is capped at thirty-five. We guessed wrong on preenrollment once and ended up with forty students. Group activities were only barely manageable, and, with only one TA, grading was a challenge. Once we tried formatting the class as a lecture course with weekly section meetings. All seventy-five students attended the lectures; the class was then split in half for the section meetings. However, this format did not engage students in the same way, and the extra hour per week that the group sections required was expensive in terms of instructor time and was unattractive to students. The faculty also found that the higher enrollment resulted in a class in which conducting a productive discussion was much more difficult. These challenges changed the nature of the class, making it far less enjoyable.

The lecture itself must be small enough that students feel comfortable (eventually) and are forced to talk frequently. The intimacy afforded by a smaller class size seems to be a requirement for engaging the non-science major in adopting a scientific role. Nonetheless, each class is different depending on the number of talkative, engaged, bright students who speak up from day one. Engaging students in discussions and introducing discussions and public thinking as a regular feature of class in the first few class meetings is imperative. At the beginning of the semester, we can reinforce the idea that lack of knowledge is not embarrassing in a classroom and that thoughtful ideas and questions are welcome even if they prove wrong. Fortunately, the history of astronomy is full of initial conclusions that proved entirely wrong. Our classroom is adorned with a color image of a planetary nebula, which, I point out in the first class, has nothing to do with planets. We discuss the origin of the term (through small telescopes, planetary nebulae often appear to the eye as green, fuzzy objects: green like the planet Neptune and fuzzy as in “nebulous”). We point out that an astronomer who bases a conclusion on available evidence later proved wrong by new evidence is not considered to have been “wrong.” Questions are encouraged or else deliberately sought. In this way, the class develops early an interactive but unthreatening tempo that will continue to thrive throughout the semester.

Crutches May Be Helpful

Most modern textbooks are big and heavy and contain far more material than the average student can possibly absorb. So why bother to adopt a textbook at all for a nonsurvey course? The answer is because (some) students seem to appreciate having a first place to look; however, an early lesson must explain how to use the textbook without getting lost in or being limited by it. I have also developed a simple website ( courses/astro2201) that follows the syllabus but takes the form of “frequently asked questions” and is not all-inclusive. Readings are assigned, but are limited and directed. Students in Astro2201 likely do not grasp all the facts contained in an introductory astronomy book, but they do know where to look should they need to know. By repetition of certain basic physical concepts under the different themes discussed in the class, we try to help students recognize that some things are inextricably linked: gravity is important on many scales and fundamental to understanding the solar system and the wider universe; our comprehension of stellar evolution leads to methods for determining the ages of galaxies; and so on.

Perhaps we will forgo the textbook crutch within the next few years. At least some, perhaps most, students today prefer to search for information digitally. Thus, we now feel obliged to discuss with students how to judge a web-site’s scholarly content. Today’s students are quickly overwhelmed with information; our job is to help them develop their quality-control skills. Pointing them to bogus websites early in the semester can help reinforce the need for critical appraisal, but this need must be reinforced throughout the semester. We also try to teach students when citation is appropriate, what plagiarism is, and what constitutes creative scholarship. We hope that these discussions have value far beyond the confines of Astro2201.

Science Is Not Straightforward
One of the most important lessons we try to teach is that posing the proper scientific question is as important as its answer. Astronomers are really detectives who are trying to reconstruct a cosmic event or circumstance based on limited information. What does the color of an object tell us about its physical conditions? What does an optical image of a galaxy convey about its mass? Some of the in-class group activities are designed to lead groups to the wrong answer or to get students to realize that they cannot deduce the answer from the information they have been given. Putting them in a situation of doubt reinforces the notion that science is not about answering the questions at the end of the chapter and that the path from question to answer is not always straightforward.

For example, in one of the first class meetings (about one week into the semester), we divide students into groups of three or four. Each group is given one of several images showing an astronomical object (see Figures 1a and 1b for two examples; they are best viewed in full color) but no other information. Each group is asked to write a description of and raise questions about the image assigned to it: What is conveyed by the white, pink, and blue-green colors in the upper image? What is the bright object at its center? Why is the latticework seen in the lower image dark? What causes part of the object to be blue while other areas seem orange? Are the colors real? These are good questions, given that at this point students have no information about the two objects other than the images. Nor have they studied how astronomers observe and what they can deduce from different types of observations. The exercise is the students’ first lesson in asking what information an astronomical image conveys.

Figure 1a: Hubble Space Telescope Image of the Planetary Nebula Known as M2-9 (the “Butterfly Nebula”)

Image of Figure 1a

Source: B. Balick et al., WFPC2, HST, and NASA. 1999.

Figure 1b: Composite Hubble Space Telescope Image of the Planetary Nebula Known as IC 4406

Image of Figure 1b

Source: C.R. O'Dell et al., Hubble Heritage Team, NASA. 2008.

When each group has completed that part of the assignment, the entire class views the collection of images. A representative for each group summarizes the description and the questions related to his or her group’s assigned image. Students are then asked to order the objects by their distance from Earth and to explain their reasoning for that order. Because this exercise takes place on only the second or third class meeting, most students have no idea what each object is or how to measure its distance, which puts them in a tough position. They have been given an impossible task, but one that perhaps makes them more sympathetic to the ancients’ attempts to explain naked-eye phenomena and more curious about how astronomers actually do determine distances.

During the remainder of the semester, whenever one of the images used in this first assignment becomes relevant, it is reintroduced, and students are able to update their understanding of it. The interpretation of images plays a critical role in astronomy. By developing their own ability to look at an astronomical image and understand what information it conveys, students learn an important lesson about how astronomers explore the universe.

Smart People Can Be Wrong

Early in the semester, we discuss the development of modern astronomical thinking. An important lesson comes from Aristotle, who rejected the heliocentric universe because parallax, the apparent annual motion of a nearby star amid the background of more distant stars as a result of Earth’s motion around the sun, had not yet been measured. The flaw in his logic was the fact that he did not understand the scale of the universe and the vast distance to even the nearest stars. (Indeed, stellar parallax was not measured until 1838, by Friedrich Wilhelm Bessel.) Aristotle did not have adequate information. Thus, while his logic was well founded, his assumptions were wrong. Throughout the course of science, and astronomy in particular, lack of knowledge has led to misconceptions and misunderstanding. The lesson to be gained is the importance of expanding the frontiers of knowledge. Throughout the semester, we revisit other cases in which new knowledge led a revolution in our understanding: for example, the recent discovery that the universal expansion is accelerating. Because we cannot yet explain what either dark matter or dark energy is, we have to prepare students for our own lack of knowledge. That scientists do not know all the answers is a natural part of science.

Our Home in the Universe

The title of Astro2201 being what it is, the course at times focuses on how unique Earth and the solar system are, and how conditions elsewhere would differ. In successive assignments, students take on the role of a member of the script-writing team for a weekly science fiction series. They are told, “In the next episode, the intrepid explorers of intergalactic space whose adventures are followed in the series will travel to a planet inhabited by a civilization comparable at least in achievement to that found on Earth in the year 2009 and located on an Earth-like planet.” In order to get students thinking about how circumstances and the eventual development of life and civilization on an Earth-like planet would differ from Earth, we give the parent star of the planet either a different luminosity, radius, mass, and surface temperature than our sun or place it in an orbit quite different from that of Earth. Furthermore, we tell students to:

Assume that the planet’s rotational period is 24 hours, that its rotation axis is inclined by 40 degrees with respect to its orbital plane, and that its orbit around the star is circular. At the same time, do not assume that the planet is located at 1 A.U. from the star. Rather, place the planet at the appropriate distance so that the star’s apparent brightness is the same as that of the Sun as seen from Earth. Do not assume that the planet’s inhabitants are human-like.

Students are then asked to develop a synopsis of the conditions on this hypothetical planet and how those conditions might favor the development of civilization, agriculture, and life-forms. The assignment forces them to think not only about these issues but about Kepler’s laws, Wien’s Law, and concepts such as luminosity, brightness, and surface brightness. In this instance, how the seasons on the planet differ from those on Earth opens up a host of questions about their agricultural, economic, and social implications for the planet. In different examples, the parent star might be a red supergiant, or even a pulsar, or might be found near the center of a globular cluster or near the galactic center. Encouraging students to think about how conditions would be different (multiple “star-rises,” for example) engages (some of) them in discussing the likely diversity of planetary systems and how important the circumstances of Earth are to us. Their essays are also often presented in an entertaining and creative way, which makes them fun to read.

Use Obviously Bad Science to Teach Science

Everyone who has stood in line at a grocery store has been confronted with the wacky science of yellow journalism. In one Astro2201 assignment, Senator Wisdom runs across the following article:

Russian Cosmonauts Travel to the Andromeda Galaxy and Discover Giant Black Hole that Threatens to Destroy Earth

Looking old and haggard but otherwise well on their return from a journey in a nuclear-powered spacecraft launched in 1965 at the heyday of the Soviet space program, a trio of cosmonauts reported today that they witnessed the extraordinary vision of a giant black hole, located near the center of the Andromeda galaxy, consuming at a prodigious rate all matter surrounding it. Stars, planets and gas, previously seen harmoniously orbiting at large distances from the center of Andromeda, are now disappearing into a dark spot which continues to shrink in size. The Solar System is thought to be threatened, according to a famous Swiss astrophysicist who reports to our correspondent that Earth will be gobbled up before the year 2017, unless “the appetite of the beast” is satiated by forcing its mass to exceed the so-called “Schwarzschild limit,” beyond which the condensation ceases to be a black hole.

The assignment continues, laying out the context for the memo the senator’s staffer must write:

Having sworn in 1957 never to let the Russians get ahead again, the Senator is seriously disturbed by this report and wonders whether the situation calls for emergency legislation getting pushed through Congress. Ever the farsighted tactician, the Senator also foresees a possible opportunity for political gain, but is nonetheless concerned about maintaining a reputation of high scientific understanding.

Students are then asked to write a brief memo pointing out what is wrong with the scientific content of this clearly crazy article. Unfortunately, the context is not wholly unbelievable to students. They know what newspapers the fictitious article refers to. Sometimes a student will even bring a copy of one of these papers to class to reinforce the point.

Science in the Arts and Humanities

Sometimes we incorporate examples from literature, art, and history that might be interesting to a subset of our students. For example, a few students may be familiar with, or at least interested in, medieval churches and their use as astronomical solar observatories as described in J. L. Heilbron’s The Sun in the Church.1 Occasionally, a student will have visited the Basilica of San Petronio in Bologna and seen its famous meridian line. In the assignment, we describe a hypothetical meridian, giving its location and describing some of its geometry. We then ask students to write a memo to a professor of art history explaining how the meridian works and, for example, what the horizontal distance should be along the meridian line between the center of the solar image on the floor of the church at noon on the day of winter solstice and the center of the solar image at noon on the day of summer solstice. This assignment requires the student to demonstrate a mastery of the celestial sphere, the solstices, and the motion of the sun, but the context is one that the more intellectually curious students might find engaging.

In other assignments, we incorporate a passage from a book or poem, using it as a means to introduce the subjects up for discussion. For example, the poem “Fire and Ice” by Robert Frost discusses the fate of the universe. Dante, in Il Paradiso, seems to understand the constancy of surface brightness, and Beatrice proposes that differences in brightness of separate areas on the moon are related to its nature and composition. One assignment introduces a passage from Italo Calvino’s Cosmicomics in which a narrator named Qfwfq observes the universe and notes: “One night I was, as usual, observing the sky with my telescope. I noticed that a sign was hanging from a galaxy a hundred million light years away. On it was written: I SAW YOU.”2 The Astro2201 assignment continues, “Somewhat startled, Qfwfq consults his diary and is ‘seized by a ghastly presentiment: exactly two hundred million years before, not a day more, not a day less, something had happened to me that I had always tried to hide.’” The assignment asks students to explain the logic behind the date Qfwfq checks (“exactly two hundred million years ago”), as well as to explore several other cosmological questions.

Using Images to Provide Focus

After a semester of looking at images, thinking about what information they convey, and learning how to ask questions about them, students are ready, in their final assignment, to be given some images that lead to a discussion of fundamental cosmology. Because hundreds (probably thousands) of websites provide summaries of modern cosmology, we strive to create a context that requires students to take their own approach. Several assignments from earlier in the semester had placed the writer in the context of working for a publishing company, writing brief paragraphs about selected images for popular “coffee table” books, or writing about black holes for children. The final paper builds on those contexts:

With the publication of the book “Images of Nature” behind you with great success and rave reviews, you head to the hills of the province of Parma, Italy for some inspiration as you sketch out ideas for a second one to be called “Hubble Reveals More than Meets the Eye.” At the stone farmhouse where you are staying, you eat a sumptuous meal in the garden and fall asleep in the sunshine over a bottle of fine sparkling wine. Shortly thereafter, you are awakened by the clinking of glasses to discover that you have unexpected company. An elderly gentleman is leafing through the folder which includes an outline of your book proposal and three images, illustrated below [see Figure 2], which you were planning to include in it. Your guest identifies himself as Fritz Zwicky, the great astronomer, who, with the help of Albert Einstein, has figured out how to travel through time and has landed, on his first trip into the future, in your garden. You, of course, are shocked and excited to be in the presence of so great a man, albeit one who died in 1974, and explain to him that you are well familiar with his brilliance and fame, particularly as a result of your recent enrollment in Astro2201. In particular, you are extremely curious to find out how he has managed this feat of time-travel, and Zwicky, in return, is extremely curious to learn more about the images in your proposed book.

You and he agree that he will tell you the secret of time travel after you fill him in on details of what the images are and how they reveal “More than Meets the Eye.” He is also very curious about the “Hubble” in the book title; he knew Edwin well since he spent most of his career at Caltech and the Mount Wilson Observatory.

You may write this paper as an essay or a dialog, but remember that Zwicky is your audience. He is a brilliant and highly educated man and is fully familiar with what was understood about cosmology 40 years ago. However, his understanding of physics and astronomy depends on different terminology than is used today and, since this is his first journey forward in time, he is not familiar with anything that has happened since 1974. It’s your job to explain to him what each of the three images conveys of relevance to the topic of “More than Meets the Eye,” and in particular how our understanding of cosmology has changed since his lifetime. Be sure to connect your discussion to each image, leading Zwicky to understand what each image shows and how to interpret its features and colors (where relevant). Since Astro2201 space-time is getting short, give your explanation in less than 1200 words.

While it is important to relate the images to your discussion, do not merely describe them; let them update him on our (but not his!) understanding of modern cosmology and the contents and history of the universe. Because of the word limit, you will have to be judicious in what topics and level of detail you include; think carefully about what content you need to include before you begin writing. Be especially careful not to go off on irrelevant tangents (such as discussions of dust in the interstellar medium, stellar populations, the evolution of stars leading to supernovae, black holes, galaxy collisions, etc); stick to a discussion of what contributes to the matter and energy density of the universe of relevance to its past history and future fate. Be sure to explain not only what we know but how we know it.

For the purpose of this assignment, please attach a citation list of all sources you consult. Also, you need not dwell on the feasibility of time travel as your guest has already promised to explain that to you afterwards.

Figure 2: Images for Astro2201 Final Paper

Image of Figure 2

Source: The three images used in this assignment are taken from (clockwise from upper left): 0310/sombrero_hst_big.jpg; 0807/j1430lens_sdss_big.jpg; and image/snwhirl_hst_big.gif.

By establishing the audience as one of the most prominent astronomers of the last century, we allow students to assume some level of astronomical knowledge and to focus on how the astronomical evidence for dark matter and dark energy has revolutionized cosmological understanding. Students have already seen the images in the assignment during earlier in-class group assignments, but the interrelationship of the images has not been directly laid out for them; they must identify the linkage themselves. In fact, a great deal of irrelevant information (as will be recognized by those readers of this essay who are familiar with the images) might be conveyed. Nonetheless, both the specific nature of the assignment and the word limit are intended to keep the essay writer focused.

If students search the Web for Zwicky (which nearly all will do), they will discover that he was quite a character and a proponent of the need for dark matter. But the need to update him on cosmology means they will have to go beyond what they can learn about him. They must summarize for him how cosmological understanding has advanced. Because he has basic knowledge of many concepts (such as the expansion of the universe), they do not have to explain every detail, and the images should lead them to the desired content. The word limit especially constrains students to consider carefully what information is most critical to the essay.


The greatest disadvantage to our course most likely is the cost of instruction and grading. We deliberately keep the class size small to encourage in-class discussion, and we have a TA for every thirty to forty students. The TA’s responsibilities include reading, commenting on, and grading papers and holding weekly office hours (at least three hours regularly, as well as on the day or two before papers are due and by appointment). The faculty instructor generally reviews the papers and the TA’s comments before they are returned to students. The feedback provided to students on their writing efforts is critical; thus, the TA must be committed to the effort required to provide quality feedback. While some graduate students prefer to be a TA in a class where they conduct recitation sections and grade tests, some appreciate the in-depth interaction with students that is expected in Cornell’s writing program. These TAs value the chance to see students show real improvement in their ability to communicate scientifically. The requirements for being a TA in a writing course are high, and we choose the most qualified students, generally native English speakers who possess well-developed writing skills and are the most enthusiastic about the experience.


Although the subject is beyond the scope of this essay, I have used a similar approach in teaching a seminar class offered to sophomore astronomy majors and concentrators. Scientists also must know how to write, to communicate their ideas and scientific results, and to develop their appreciation of context and audience.

In some instances, the assignments I have made for the science majors’ class and Astro2201 have been similar. Reviewing the two groups’ responses to similar assignments has shown me how differently the two groups use language. Even when the scientific concepts are the same, the non-scientist uses more vernacular—simpler, familiar words—whereas the scientist quickly adopts mathematical or technical jargon. The non-scientists are not wrong in their expression, but their language is different. By understanding how the two groups use language in distinct ways, I have been better able to adapt my teaching to each group, which, I believe, has helped me become a better lecturer.

One of the most interesting experiences in the class taught for majors has been a “symposium” that we organize toward the end of the semester. Typically, the symposium focuses on a particular theme, with each student assigned to write a paper and make an oral presentation reviewing an article from the professional literature. The written papers are revised and published electronically in a “symposium proceedings.” (A selection of the proceedings can be found at Orchestrating the symposium and publishing the proceedings creates a fair amount of work for my graduate assistants and me, but seeing the final, impressive product is immensely satisfying for us—not to mention for the students.


The course format adopted for Astro2201 is unlikely to fit all situations. Because not every fact or important topic is discussed in detail, a student who planned to take a higher-level astronomy course after taking Astro2201 would probably find we had skipped over some concepts that a survey course would have covered. On the other hand, we can claim that our writing assignments require more processing and synthesis of information and that they take students well beyond the memorization of facts or the repetition of concepts that is often expected in a survey course. Writing can be a natural medium for learning about any topic, including science.3


1. J. L. Heilbron, The Sun in the Church: Cathedrals as Solar Observatories (Cambridge, Mass.: Harvard University Press, 1999).

2. From the short story “The Light Years,” in Italo Calvino, Cosmicomics (Le Cosmicomiche) (New York: Harcourt, Brace & World, 1968), 127.

3. Over the years, I have often taught Astronomy 2201 in collaboration with Riccardo Giovanelli, whose wit, vast knowledge of everything from Mayan writings to black-and-white movies, and complementary approach to teaching have helped shape the course as it is today. I also greatly appreciate the continuing encouragement and support of Keith Hjortshoj, director of the Knight Institute Writing in the Majors program at Cornell, especially for his nurturing the astronomy graduate teaching assistants. Finally, I send my thanks to the many undergraduate students who over the years have participated in—and seemingly enjoyed—Astronomy 201/2201 and to the graduate teaching assistants whose communication skills and commitment to education have often inspired me.