Reading Astronomy News: Chasing Down the Mystery

Credit: Sloan Digital Sky Survey,


Once in a while something new happens. In the case of an article published in The Atlantic, astronomers observed an object that had properties like those of a supernova explosion, but much too fast. That led to some detective work across the electromagnetic spectrum to try to figure out what was happening!


1. What event triggered astronomers to pay attention to this particular location in space?

Answer: A bright spot appeared where none had been before.


2. How did astronomers communicate with each other that something interesting was happening?

Answer: They used The Astronomer’s Telegram, a global astronomy alert system.


3. Where did the event happen?

Answer: This event occurred in a nearby galaxy. It was detected at a telescope in Hawaii. (Note: I would use answers to this question to find out if students have sorted out what an “event” is, and the difference between an “event” and the detection of it.)


4. What about this event made it clear that this was not a “normal” supernova?

Answer: It was too bright, and also faded away too quickly. This is weird because brighter supernovae should fade away more slowly, not more quickly.


5. What is the current working hypothesis about what happened in the event?

Answer: Astronomers think this may have been the formation of a black hole or a neutron star.


6. How will astronomers test this hypothesis?

Answer: This event is over, so astronomers will have to wait for another one to occur to test their ideas against observations of that future event.

Book Recommendation: Hawaiki Rising

Hawaiki Rising

By Stacy Palen

On May 18, 2014, Hokule’a left Oahu for a 3-year voyage that would take her and her sister vessel, Hikianalia, around the globe. The journey covered 47,000 nautical miles with stops in 26 countries, and ended in Hawaii on June 17, 2017. The vast majority of the navigation on this journey was celestial navigation. Specifically, the celestial navigation of pre-contact Pacific Islanders. The voyage was a celebration of the revitalization of an art and a science that were nearly lost to the world.

In his book, Hawaiki Rising, Sam Low tells the story of the rediscovery of this lost art. The book reads like a mystery story with adventure chapters. Along the way, it covers the principles of the celestial sphere in a fair amount of detail.

The story begins with a very brief history of Captain Cook’s discovery of Hawai’i and the aftermath. This sets the stage for the shift in culture that caused the art of navigation to be lost and simultaneously hints at the trail of breadcrumbs that would be followed in order to rediscover this ancient art. After a brief nod to Thor Heyerdahl, whose famous voyage forms the basis of the movie Kon Tiki, the story shifts to following the “detectives” in 1968 who asked the question, “How did they do it?” By the seventh page of the main text, we are already on the trail of the answer to that question.

Two of the most interesting characters along the way are Mau Piailug, known simply as Mau, and Nainoa Thompson. Mau learned to navigate “the old way”; from oral tradition stretching back generations, and Nainoa Thompson learned from him as a young adult. Nainoa Thompson is now the President of the Polynesian Voyaging Society, and knows more about this method of navigation than anyone else, at this point. Not long ago, he gave a talk on the experience at Stanford, which I highly recommend. 

The astronomical content is spread throughout the book and is all related to the celestial sphere and the appearance of the sky from various locations. As such, it does not provide content that is broadly applicable across the whole course, but it does provide a fascinating motivation for learning the content in those initial few chapters. We often mention “people used to navigate this way,” but beyond talking about finding the North Star, we tend to gloss over the details.

For myself, this book gave me new ideas for how to motivate that section of the course. Many students are already somewhat familiar with these ideas from the Disney movie “Moana,” in which a young Pacific Islander girl sets out to rediscover how to navigate the oceans. The movie gets it right, which is encouraging. Students are interested to learn that a movie they loved has an application to what they are studying in class.

Students in a book group will undoubtedly stumble across the PBS documentary The Navigators: Pathfinders of the Pacific, directed by Sam Low and Boyd Estus. The film centers on Mau Piailug, the last known navigator from the Micronesian islands, who was so instrumental to the revival of this type of navigation. In 57 minutes, the film cannot possibly cover the story, and especially the astronomy, at the level of detail of the book.

It would be interesting to try combining all these resources in one semester: First, assign students to watch Moana, or at least watch the clip of the song “We Know the Way.” Read the book throughout parts of the semester, then watch Nainoa Thompson’s talk. Finish by watching the PBS documentary. Comparing and contrasting the three different treatments of the material would allow for interesting discussions that draw on students’ competencies beyond the astronomy classroom.


Book Recommendation: Unstoppable

Screen Shot 2019-06-06 at 1.07.30 PM

By Stacy Palen

Perhaps I should not have been surprised to find out that many of my students see Bill Nye (the Science Guy) as a personal hero, but I was. It’s probably got something to do with the bow ties…or the lab coat…or something.

I was too early for Bill Nye, but I was young enough for Carl Sagan’s original Cosmos, and still remember the impact it had on my young brain. So I was delighted to find that my current students have someone who inspires them in the same way. I suspect that in a decade or so I will see students for whom Neil deGrasse Tyson is the person who inspired them when they were very, very young.

At any rate, Bill Nye has several books out which are broad in scope and only peripherally related to astronomy concepts. Still, if my students love Bill Nye, I’m perfectly willing to harness that in the interest of getting them to read about science, even if it’s slightly off-topic!

Of all his books, the one most closely related to the coursework is Unstoppable: Harnessing Science to Change the World. This book lays out the scientific case on climate change before looking at the solutions required on both the national and global scales. Bill then dives in for a look at his own home through a friendly competition that he has going with Ed Begley Jr. for the greenest home in town. He finishes with an optimistic call to action.

Students will find here an antidote to the despair that sometimes overtakes them at the end of the chapter on atmospheres; when they have started to internalize the science of climate change but haven’t yet started to figure out what solutions look like and how to achieve them.

Students often ask me for this material, but there is little time to cover it during the astronomy course (we have an entire course in our Department about solutions that I recommend to them).

The material is at a completely accessible level for students and the public. Also included are a handful of experiments that students can do on their own, like heating up water in the microwave (not to the boiling point) to see that hot water takes up more space than cold water.

Reading and discussing or writing about this book would, I feel, satisfy general education learning objectives based around “Science and Society;” particularly if students are asked to tie the material back to the information about atmospheres that they learn when comparing Venus, Earth and Mars.

It’s an optimistic take on the subject from someone that students already admire and trust. If you decide to assign it in your class, I’ll be interested to hear about how the experiment goes!

Reading Astronomy News: This Interstellar Asteroid is Accelerating


By Stacy Palen

As I was working on the first draft of Chapter 3 for the fourth edition of Understanding Our Universe, I ran across this wonderful summary article about ‘Oumuamua by Steven Spence of GotScience Magazine. You probably remember that ‘Oumuamua is the first interstellar object that we’ve observed in our Solar System. This article compactly lays out the case for how we know it comes from another star, how fast it’s moving, and why its acceleration as it leaves the Solar System is “weird." It’s practically chapter 3 in a nutshell! 

To read This Interstellar Asteroid, by Steven Spence, click here.

  1. In the discussion of where ‘Oumuamua came from, the author states that it is “moving on an open hyperbolic trajectory.” Make a sketch of what such a trajectory would look like. How is it different than a path followed by an orbiting object?

    Answer: They should draw a hyperbola; many will have to look this up. A hyperbola is not closed, like an ellipse is closed.

  2.  ‘Oumuamua’s trajectory is described as having an eccentricity of 1.23. But the maximum eccentricity for an ellipse is 1.00. What is the resolution of this apparent contradiction?

    Answer: Only objects that are orbiting, and bound to the system by gravity, travel on ellipses. Objects that are unbound can travel on trajectories that don’t meet the requirements for an ellipse.

  3. In the article, ‘Oumuamua’s speed is described as fast enough to cover the distance from Earth to the Moon in 73 minutes. The New Horizons space craft covered the same distance in 8 hours. Approximately how many times faster is ‘Oumuamua traveling than New Horizons?

    Answer: In “cowboy” math, 73 minutes is about an hour. So ‘Oumuamua must be traveling about 8 times faster than New Horizons, to cover the same distance in an 8th of the time.

  4. ‘Oumuamua reached the orbit of Jupiter about an hour earlier than expected. Why does this imply that the object has accelerated?

    Answer: In order to cover the distance in less time than expected, the object must be traveling faster than expected. This means there must be an unexpected increase, or less-than-expected decrease, in the speed of the object.

  5. The best idea, currently, for how ‘Oumuamua is accelerating is that it is “comet-like outgassing.” Outgassing occurs when a jet of gas shoots out from the object. Use Newton’s third law to explain how an object “outgassing” can cause an object like ‘Oumuamua to accelerate.

    Answer: This is exactly how a rocket accelerates! Because it is a closed system, if some of the mass accelerates in one direction, there must have been a force that pushed that mass. By Newton’s third law, there must be an equal and opposite force pushing the rest of the mass in the opposite direction.




Reading Astronomy News: Earth’s Magnetic Field On The Move

Earth's Magnetic field
Image Credit: Emmanuel Masongsong/UCLA EPSS/NASA

By Stacy Palen

In January, geologists updated the model of Earth’s magnetic field, a year ahead of schedule.


1. Study the map titled “Magnetic Motion.” How much time separates each pair of red dots between 1900 and 2010?

Answer: The dots indicate 10-year time intervals until 2010. There is an extra dot placed for 2015.


2. In general, how does the movement of the magnetic pole since 1990 compare to the movement of the pole prior to that time?

Answer: Because the red dots are much farther apart after 1990, we can conclude that the pole is moving a lot faster in the last few decades than it did prior to that.


3. Why do we care about what happens to the magnetic pole of Earth?

Answer: The position of the magnetic pole underlies all navigation. If we don’t know where the pole is, we don’t know where we are.


4. Why did geologists decide to update the model a year earlier than expected?

Answer: Because the position of the pole was changing so fast that navigation was becoming inaccurate.


5. What is the working hypothesis for why the position of the magnetic pole is changing so rapidly right now?

Answer: A jet of liquid iron is weakening the magnetic field in Canada. This means that a second patch of magnetic field in Siberia is relatively stronger, so the pole is moving in that direction.


6. How does this news article relate to what you have learned about Earth’s magnetic field?

Answer: We have learned that Earth’s magnetic field changes over time, and that the history of those changes are recorded in rocks. We have also learned that the magnetic field affects the aurorae in Earth’s atmosphere. As the magnetic field changes, this should affect the aurorae as well.

Current Event: The Eta Aquariids are Coming!


By Stacy Palen

Don’t forget to remind your students about the Eta Aquariid Meteor Shower, coming in the beginning of May.  The peak occurs around May 4-5.  This is the last chance for most of us to remind Spring semester students to go out and watch a meteor shower!

This meteor shower occurs when Earth passes through the debris left behind by Halley’s Comet.  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.  The particles burn up, creating meteors as they fall through the atmosphere. This will happen repeatedly at particular times of year, as Earth returns to the same point in its orbit. 

Halley’s comet has a 76-year orbit, so it is a short-period comet. It will not be back in the inner Solar System until 2061.

To watch a meteor shower, go to a clear dark sight 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.

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!