Reading Astronomy News: The Lyrids are Coming!

Meteor Shower

Image Credit: NASA/Bill Ingalls

By Stacy Palen

Don’t forget to remind your students to watch for the Lyrid Meteor Shower this month. The peak occurs around April 21-22.

This meteor shower comes as Earth passes through the debris left behind by Comet Thatcher. Particles lost from the comet continue to drift in the Solar System, gradually changing their position.

As Earth moves through space, it passes near the trajectory of the comet and runs into collections of these particles. This will happen repeatedly at particular times of the year as Earth returns to the same point in its orbit. The particles burn up, creating meteors as they fall through the atmosphere.

Comet Thatcher has a 415 year orbit, so it is a long-period comet. It will not be back in the inner Solar System until 2276.

To watch a meteor shower, go to a clear dark site where the horizon is not obstructed. Spend about half an hour in the dark, without your cell phone or other bright light in view. This will allow your eyes to adapt to the dark. Then just watch for meteors! They are best seen with the naked eye.

If you are careful and methodical, your observations can contribute to the study of meteors and meteor streams! To learn more, visit the Astronomical League’s Meteor Observing Program website.

Resources: First Ever Image of a Black Hole

By Stacy Palen

My students came in talking about this, and so I thought I’d pass on a couple of resources that I used while answering questions in class! 

I felt I needed to put the new image in context, with respect to M87 and all its fascinating parts.  This photo has the angular sizes labeled, as well as the wavelengths of the observations. It’s a quick place to get all those numbers right away.


ESO has an image of the global array:

Veritasium has a nice short explainer video about the light paths:

Which then matches beautifully onto the actual image and has some fun information about the technical difficulties with data transfer etc.:

I made a point of taking them to the summary research paper:

Both so that they could just see it, but also because I wanted to show the author list and acknowledgements. This is an important thing that science does: model how to have international collaboration. The paper summarizes the achievement nicely: “In conclusion, we have shown that direct studies of the event horizon shadow of supermassive black hole candidates are now possible via electromagnetic waves, thus transforming this elusive boundary from a mathematical concept to a physical entity that can be studied and tested via repeated astronomical observations.”

We happen to have just done two of the Learning Astronomy by Doing Astronomy activities about black holes: Bent Space and Black Holes, and Light Travel Time and the Size of a Quasar. So, this was a lucky moment when we were all thinking about these concepts anyway!

Book Recommendation: Present at the Beginning: Galileo’s Sidereus Nuncius


By Dr. Bradley W. Carroll

We live at a unique point in history. For the first time, we humans know the entire story of our species, at least in broad outline. We know how the universe expanded from the initial Big Bang, how generations of stars manufactured a periodic-table’s worth of elements and then dispersed them throughout space as those stars exploded, and how clouds seeded with those elements gravitationally collapsed to form planets. We understand the evolution of the life that arose on this particular planet, and how an astronomical impact led to the dominance of the hairless apes that eventually became our friends and neighbors.

But what was it like to be alive four centuries ago when almost everything was a mystery? What was it like to discover, for the very first time, that the Moon has mountains, that there is a universe filled with stars we cannot see with the naked eye, and that other moons orbit Jupiter? Fortunately, we know exactly what it was like because the man who made these discoveries has told us: Galileo Galilei.

Sidereus Nuncius (The Starry Messenger) is not filled with the dry dialectics of Galileo’s other tomes. In this book you can sense Galileo’s exuberance, his sense of wonder at what he has seen for the very first time through the crude telescope he made with his own hands. He tells you how he labored over its construction until he could see objects “over sixty times larger.”

Galileo writes that “having dismissed Earthly things, I applied myself to explorations of the heavens.” He grabs your sleeve to pull you toward his eyepiece so you can see these wonders for yourself.

And what wonders they were to his eyes! Galileo sees the tops of mountains on the Moon lit by the Sun, and asks us, “On Earth, before sunrise, aren’t the peaks of the highest mountains illuminated by the Sun’s rays while shadows still cover the plains?” Galileo alone now knows that the Moon is not a perfect sphere. Using shadows, he calculates that one lunar mountain is “higher than 4 Italian miles.”

Galileo swings his telescope toward the constellation of Orion, and breathlessly tells us that “to the three [stars] in Orion’s belt and six in his sword that were discovered long ago, I have added eighty others.”

Then, on January 7, 1610, Galileo trains his telescope on Jupiter to see “three little stars” near Jupiter that are “arranged exactly along a straight line and parallel to the ecliptic.” Night after night Galileo keeps track of these stars, now grown to four, as they stalk Jupiter, passing back and forth across its disk.

Finally, on March 2, Galileo calls them “planets,” and later, the “Medicean planets.” (In the opening passages of Sidereus Nuncius, Galileo, in his never-ending quest for patronage, proposes naming these four moons of Jupiter for Cosimo II de’ Medici, the Fourth Grand Duke of Tuscany.)

Thirty years ago, I attended a meeting of the American Astronomical Society in Ann Arbor. There on display was a draft of a short letter Galileo sent to the Doge of Venice on August 24, 1609 that described his telescope. But at the bottom of the letter are Galileo’s first recordings of the moons of Jupiter, made on this paper he happened to have nearby.

I felt overwhelmed knowing that when Galileo’s hand made these marks upon this sheet of paper, the world changed. Galileo now knew with certainty that Earth was not the center of the all things, because here were four moons orbiting Jupiter. Galileo went on to make more astronomical discoveries. He discovered spots on the Sun and the phases of Venus, but his Sidereus Nuncius announced his first discoveries to the world.

Reading the Sidereus Nuncius, I am struck by encountering a fully modern mind, so different from the mysticism of Johannes Kepler. It marked a revolution. After Sidereus Nuncius, astronomy no longer had to rely on the word of ancient authority for its conclusions. Astronomy became an observational science, and anyone with a telescope could see what Galileo saw. Sidereus Nuncius is a short book, just 62 pages. My version, translated by Albert Van Helden, has useful notes along with an introduction and conclusion. Read it for yourself and be present with Galileo at the beginning of modern astronomy.


How-To: Orchestrating Active Learning in a Less-Than-Ideal Environment


By Stacy Palen

Somehow or other, classroom architects in the 1960s, 1970s, and as far along as the 2010s did not get the memo that instructors would sometimes want students to work together on projects. It’s a mystery. Even in our two-year-old science building, the lecture halls are set up for presenting to large groups. This is fine, but presents a challenge when I want to have students collaborate.

Often, I’ll put students in groups of two for brief discussion on things such as clicker questions or to work through a worksheet. “Groups” of two are easy to accomplish. But sometimes, we just need more room, either to work in groups of three or four, or to work with “manipulables” like paper moons or large maps.

When this happens, I need an advance plan. Typically, I will need about twice as much space as I have in the seating area of the lecture hall. I’ll look for space in the front or back of the lecture hall, and down the stairs on either side of banks of chairs, and estimate how many groups of 3–4 I can fit in those areas. I will scout out nearby alternative locations for students to work, like a stairwell, outdoor retaining wall, or atrium. Sometimes there are groups of chairs at the end of a hallway, or benches outside the classroom.

At the beginning of class, I’ll spend a few minutes on the typical introduction to the activity and the material, and then I’ll invite the students to spread themselves out to work in the spaces I’ve designated. About a third of them stay in the seating area of the lecture hall, turning backwards and kneeling in their chairs to work with the people behind them. The rest move out into the larger spaces and form into small groups.

I spend the rest of the time walking through those spaces: interrupting groups who’ve gone off track, or who aren’t making progress, gently nudging students to ask better questions and suggesting that student X take a turn holding the paper “Moon.”

It sounds like chaos, but it actually works out very well. One unexpected benefit is that I am harder to find. This means that students must struggle on their own a bit longer before they can ask me for help. Often, that little bit of “extra” time lets them solve their own problem.

I’ve never had a student complain about this, nor have I heard from the professors teaching in neighboring classrooms that it has been in any way disruptive. Sometimes, they just shut their door.

I have, on occasion, had students who are wheelchair users or whose mobility is restricted in some other way, and so I make certain to keep an eye out for any obstacles to group inclusion, physical or otherwise. Most always find a group without issue, but I do keep an eye on the situation, just in case.

Possibly the most common question I get asked about active learning is, “How can I do this in a lecture hall?” Depending on the individual situation, it may be difficult. But take a look around—often you might find you can “rent” a little space outside the confines of the lecture hall for the fun activities you want to do!

How-to: Learning is a Social Phenomenon

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By Stacy Palen

As I mentioned in the last post, David Brooks recently collated several different studies of teaching and learning into an Op-Ed for the New York Times titled “Students Learn From People They Love.” Two paragraphs of this article particularly caught my attention; one about brain activity in a group, which I discussed in my last post, and the subject of this week’s post about in-person vs video teaching.

Brooks states in his article:

Patricia Kuhl of the University of Washington has shown that the social brain pervades every learning process. She gave infants Chinese lessons. Some infants took face-to-face lessons with a tutor. Their social brain was activated through direct eye contact and such, and they learned Chinese sounds at an amazing clip. Others watched the same lessons through a video screen. They paid rapt attention, but learned nothing.

This study reminded me of a welding course I took last year, in which the welding instructors were testing two different ways to teach welding.

The first method used real-time feedback from a computer/robot setup, which had lights and sounds to let you know when you moved the welding tip too fast or too slow. The second used a more traditional combination of videos and live instruction. I was in the second group.

I found that I could watch the instructor do something once, and then feel competent to try it myself. While my hand-eye coordination needed development, and I couldn’t necessarily make the weld as smoothly as I wanted, I easily remembered the series of steps required.

But if I was learning by video, I had to watch the video multiple times, and once I even had to stop in the middle of a weld to remember how to do what came next (turn a corner, as I recall).

I did not get to participate with the “robot teacher” but heard later that it was not as effective as the live instruction.

Students came to rely on the robot feedback rather than actually training their own eye. They made great welds as long as the robot was there to continuously correct them. But the students did not make the next step to being able to determine on their own that a correction was needed.

That’s interesting, it implies that correction alone will not help a student to identify their mistakes, even in real time; something more is required.

In another recent experience at a “meet the candidate” event for people running for local school board, a member of the public asked me why public education has not taken greater advantage of internet-based learning to keep costs down. His premise was, in my opinion, faulty in two ways.

First, education has taken advantage of the internet more than most fields.

Second, as I stated at the time, if the internet was going to replace teachers, then books would have done so, or television, or DVDs.

But we’ve all had the experience of watching the TV show or the video, and then being completely unable to repeat the task on our own. In fact, there’s a whole new series of “nailed it” shows that poke fun at this very human experience.

Clearly, some things can be learned from watching, and some by reading. But other things need to be learned by doing, and they are learned faster and more effectively with a person who can show you how. Research into learning and neuroscience is beginning to figure out why, and it’s fascinating!

How-to: Learning Relies on Soft Skills


By Stacy Palen

David Brooks recently collated several different studies of teaching and learning into an Op-Ed for the New York Times titled “Students Learn From People They Love.” Two paragraphs of this article particularly caught my attention, one about in-person vs video teaching, and one about brain activity in a group. I’ll talk about each one separately, in this and the next post.

In the article, Brooks writes, “Suzanne Dikker of New York University has shown that when classes are going well, the student brain activity synchronizes with the teacher’s brain activity. In good times and bad, good teachers and good students co-regulate each other.”

This one caught my attention because I’m not at all sure what “synchronized brain activity” means. It sounds a little…unscientific.

But when I think about it more, I’m pretty sure I have a guess about what it feels like. I bet you do too.

We’ve all been in a classroom where the professor and the students were all working toward a common purpose, and we felt like the professor knew our questions before we could articulate them. Even hard things seemed approachable, because the professor was keyed in to our confusions. We would work extra-hard to please those teachers, and it paid off with faster and deeper learning.

On the other side of the desk, we’ve all had those students who helped clarify for us the confusion in the classroom. For better or worse, there’s sometimes that one kid who seems to respond to what we are saying just a little bit quicker. And when her eyebrows furrow, we pause and back up and try to explain again.

This sometimes extends to an entire classroom of students. I’ve had back-to-back classes in which the classroom vibe was completely different. In one hour, the group was chatty and involved and asked questions and was prepared each day. And the next hour, it felt like pulling teeth just to get them to actually push a button to answer clicker questions.

But all of this is very “fuzzy,” and that makes us uncomfortable. We would love to have a concrete set of steps to take so that if we want to improve student outcomes by 7.3%, we can simply invoke 20% more clicker questions in the classroom, and the student outcomes would improve accordingly. But if that were true, we would all be teaching perfectly already. It cannot possibly be so formulaic or teaching astronomy would be done by reading the cookbook.

Be reassured by the burgeoning research that learning is a social experience. It’s an interaction and therefore, each teacher-student pair does it differently. What works for me won’t necessarily work for you. And what works for you with student X won’t necessarily work with student Y. And even what works with student X for topic A won’t necessarily work for topic B!

This can be frustrating, but it also makes teaching fun and exciting. Teaching is a giant research experiment, where you are always trying something new, to see how it works. Not because there is one right answer, but because there are a hundred right answers, and matching up the method to the topic and the interaction is a subtle art.

The elephant in the room, of course, is evaluation. Brooks points out:

The bottom line is this, a defining question for any school or company is: What is the quality of the emotional relationships here?

And yet think about your own school or organization. Do you have a metric for measuring relationship quality? Do you have teams reviewing relationship quality? Do you know where relationships are good and where they are bad? How many recent ed reform trends have been about relationship-building?

In my experience, the answer to all of these questions is no because it’s really hard to measure these “soft skills,” like relationship building and communication. It’s much easier to measure changes in learning that are made by a change of specific instructional techniques than those that rely on interpersonal relationships between a teacher and their students.

So then the very best answer is to try things, all the time, to find the set of techniques that work best for you in your classroom with your students. And then sit down at the end of term and write down your thoughts for your evaluation file.

Explain what you tried, and why you think it worked or didn’t work, whether you’d try it again, and what you’d change. Your teaching will only benefit from the moment of reflection, and I suspect the committee that evaluates your work will too.

Classroom Resources: Astronomy in Action- Angular Momentum

Stacy Palen has created 23 videos on key topics to accompany her textbooks, Understanding Our Universe and 21st Century Astronomy, that instructors can assign as pre-class activities or show in class. A mixture of live demos and mini lectures, these videos explain key concepts in an understandable and compelling way. In the angular momentum video, Stacy stands on the “rotating platform of doom” and is given a small shove with outstretched arms, and then brings those arms in close to her body to demonstrate the conservation of angular momentum. Watch the video below and let us know what types of live demos you do in class!

How-To: Confronting Gender Bias in the Sciences

Girl Stars1

By Stacy Palen

The article from Nature Ecology & Evolution, How the Entire Scientific Community Can Confront Gender Bias in the Workplace, came across my screen recently, and it occurred to me that many astronomy professors might not see it…

I find that while evidence of gender bias is well-documented, approaches to changing that bias are harder to come by. Near the end, this article provides some scientifically-minded suggestions for tackling the gender bias problem that we may all find helpful. It’s important to note that this article is coming from the biological sciences, which statistically have a smaller gender bias problem than the physical sciences.

As I read the piece, I was reminded of a particularly formative interaction I had as a young scientist. When I interviewed at graduate schools, I talked to lots of professors of both physics and astronomy, since I hadn’t yet decided how I would specialize.

As an undergraduate, I had taken one subpar introductory astronomy course which didn’t make the field seem very appealing—the class primarily focused on memorizing which stars were in which constellations that were visible at what times of the year. (There was also a lot of talk about epicycles, which took me nearly two years to eradicate from my brain, in order to make room for ellipses.) So astronomy was on my radar, but only peripherally. At the time, it seemed to me that something closer to industry might be a wiser choice.

During a visit, one professor made an off-hand comment that would alter the trajectory of my life: “Of course,” he said, “there are lots of women heroes in astronomy…” And that was it. In that moment, I decided I wanted to find out more about those women heroes, and the obvious way to do that was to specialize in astronomy and astrophysics.

Go figure. Sometimes the smallest, most insignificant interactions can change a life…

I’m positive that this professor doesn’t remember the interaction. I know this because I later asked if he remembered my visit (for another reason), and he didn’t recall it. I don’t blame him—I too have had former students say to me, “You said this one thing, one time, that changed my life…” and had absolutely no recollection of it. It’s difficult to know how our most off-hand interactions affect other people.

Lately, I’ve been trying an experiment in which I include more women and minority scientists in my classes but do NOT make a big deal of pointing them out; instead, I just mention them casually, as though it happens all the time. I’m interested to see how this affects my students in the future.

I'll have the luxury of interacting with some of these students again in later years, both in other classes in the department and across campus. And I’ll probably devise some sneaky way of asking a question on a homework or exam to find out if they noticed. I’ll let you know how it goes…

Book Recommendation: Glass Universe


By Stacy Palen

A few weeks ago, Colin Inglefield wrote a guest post about his uses of trade books in the classroom. Over break, I finally had a chance to read Glass Universe by Dava Sobel, and I think this would make a great book to use in this context. The book is about the early years of the Harvard Observatory, and the women “computers” who worked there. I am considering using this text for Astro101 next fall.

There are several themes running through the book that might be used to guide discussion throughout the semester.

The first is the science and society angle; there’s a lot to talk about here, of course, about the role of women in science, and how the larger society’s norms decide who gets to play along in the sciences, and in what role. Then there’s the question of who gets the credit. In recent years, it has become increasingly well-known that Rosalind Franklin was robbed of recognition for her critical involvement in the discovery of DNA due to her gender. Sobel tells a parallel story in astronomy about Cecilia Payne-Gaposhkin, and her 1925 thesis that began a revolution in astronomy by discovering that stars have fundamentally different compositions than planets. Why is her name not as well-known as Chandrasekhar’s? That’s an opening point for a wide-ranging discussion about not only the role of women in science, but also general fairness (think of the recently renamed Hubble-Lemaitre Law).

The second is about the symbiotic connection between technology and science. (This is covered more directly in another trade book, Starlight Detectives by Alan Hirshfeld.) Hirshfeld convincingly argues that the revolution in photography created a corresponding revolution in science, because scientists were able to store objective data for the first time. This meant that multiple scientists could analyze the same data, and compare data points over time. Hirschfeld follows this thread through Henrietta Leavitt’s work on different types of variable stars, Annie Jump Cannon’s work on spectroscopy, and Cecilia Payne-Gaposhkin’s work on elemental abundances, and reveals why these discoveries could not have been made in Newton’s time, for example, the record-keeping ability that photography provides simply didn’t exist. Similarly, telescope technology was improving by leaps and bounds during this time, and internally consistent observations from both hemispheres became possible.

The third theme is about the role of private and public philanthropy in science. Most students are not aware of how science is funded today, nor how it has been funded in the past. The funding sources dictate, to some extent, what projects are pursued. At the Harvard Observatory during this time, Mary Ann Draper’s interests were decisive to the success of the observatory, and dictated to some extent the avenues of inquiry that were followed. There are benefits and drawbacks associated with privately funded science just as there are with publicly funded science. Deciding on the balance between the two funding sources is a current argument unfolding in the political sphere and in the larger society. This book helps illuminate the extent to which science in the past was dependent on the individual inclinations of wealthy donors. It’s for your students to decide whether they think the system has improved or not!

I’ll use this book for an experiment with book discussion groups in fall semester. I’ll let you know how it goes! Let me know if you decide to try something similar.

Reading Astronomy News: Updated Graphic of LIGO/Virgo Compact Binaries

By Stacy Palen

LIGO has been busy, and a newly released graphic summarizes many of the exciting discoveries the detector has made in concert with Virgo, its European counterpart.

Summary: Since 2015, the LIGO/Virgo collaboration has detected gravitational waves—ripples in spacetime caused by rapidly accelerating massive objects—from 10 stellar mass binary black hole mergers and one binary neutron star merger. Black holes and neutron stars are both forms of stellar remnants—the final stage of stellar evolution that a star enters when it has burned through its entire fuel supply. This graphic provides a great jumping off point for discussions about masses in the stellar graveyard.


1. Consider the final masses of the black hole mergers (larger blue circles). What is the smallest merged mass?

Answer: About 19 solar masses.


2. Consider the masses of black holes that have been detected in X-rays (EM Black Holes, in purple). What is the largest black hole mass that has been detected this way?

Answer: About 23 solar masses.


3. Estimate the average mass of the black holes that have been detected in X-rays.

Answer: About 10 solar masses.


4. Estimate the average mass of the black holes that have been detected in gravitational waves.

Answer: This average looks to be about 25 solar masses.


5. Astronomers make the claim that they are detecting a “new population of black holes” with gravitational waves---—that is, that the type of black holes they are detecting now are different than the ones they were detecting before. Based on your answers to questions one through four, explain why they would say this.

Answer: Even though the two groups of black holes overlap in mass, gravitational waves are detecting more massive black holes, on average, than were detected with X-rays in the past.


6. Compare the number of EM black holes to the number of black holes (before merging) discovered with LIGO/Virgo. How much has LIGO/Virgo contributed to the total sample of known black holes?

Answer: LIGO/Virgo has nearly doubled the number of black holes that have been observed.


7. Is it reasonable, then, to compare the two populations (the pre-merger black holes from the LIGO/Virgo data and the X-ray black holes)?

Answer: Yes, statistically speaking, we know of about the same number of objects in each case.


8. Consider the masses of Neutron stars (yellow). What is the largest neutron star mass that has been detected with light (EM)?

Answer: About 2.1 solar masses.


9. Consider the masses of Neutron stars (yellow). What is the average neutron star mass that has been detected with light (EM)?

Answer: About 1.5 solar masses


10. Theorists predict that we would not expect to observe neutron stars with masses above about 2.14 solar masses. Are these observations consistent with that prediction? What do you think astronomers are wondering about the post-merger object resulting from the merger of two neutron stars?

Answer: The neutron stars observed with light are consistent, but the outcome of the neutron star merger is a little bit too massive. As of this writing, astronomers are still trying to figure out the form of that post-merger object. It could be a black hole, a neutron star collapsing to form a black hole, or a stable neutron star. More data are needed!