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November 2022

Classroom Stories: Teaching Astronomy to Primarily Non-science Students in Group-setting Activities, by Sandi Brenner (Bryant University)

I teach an Introductory Astronomy course at Bryant University – a small university with a total undergraduate enrollment of a little over 3,000 students.  Although Bryant University has a College of Arts & Sciences (which included only one ‘Department of Science’,) and now a School of Health and Behavioral Sciences, it is well known for its College of Business.  This is where most of my students come from.  In my class, I try to not only teach them all about our amazing universe, but also ‘how’ we know all of this.  Sometimes the ‘how’ is mathematical and sometimes it isn’t.  I’ve also run into semesters where we get so far behind (a semester when we seemed to have a class-canceling snowstorm every week or many tech issues during COVID), that covering the entire syllabus was very challenging.  So, over the years of teaching, I have developed a number of in-class group activities (“In-class Homework”) that help in my mission.

When I started these activities, some of them were begun in class, but had an ‘out of the class’ component.  Unfortunately, group dynamics don’t always work well, and a number of students had trouble meeting with their group outside of class, resulting in reduced grades.  These were in the days before zoom, so to solve this, all activities are now only in the classroom.  Fortunately, my class meets for 1¼ hours, so there is time for the activities and then (sometimes) time left over to return to the class lecture.  Mathematically speaking, I am dealing with a math-challenged group.  Ask them to calculate, for example interest, they can do it in their sleep, but the minute I ask them to calculate circular velocity, they look at me like I have two heads.  These are smart students, but many of them tell me “I don’t understand science.”  Hence my challenge!

I cover Kepler’s Laws and Newton’s Laws early in the semester.  To show the importance of math in astronomy and spaceflight, I developed a multi-part group activity where the premise is that the group is the first manned mission to Mars.  Think The Martian but with no infrastructure on the planet.  In part 1, I have the students calculate the spacecraft’s orbital period and semi-major axis using Kepler’s Laws, as well as the round-trip travel time needed for a simple conversation between astronauts on Mars and mission control on Earth.  In part 2, they calculate first the escape speed needed to leave Earth’s orbit, then the speed of Mars in its orbit.  The students work in groups, but each student submits their calculations for grading.  I do walk around the room to help the students as needed (and often a lot is needed, including how to use the calculator to complete the calculations.)  At the end of the ‘part 2’ activity I show them the clip from The Martian where Rich Purnell explains his proposal to the group (my favorite scene of the movie – ‘the math checks out’.) 

I also have several non-mathematical activities that I’ve used, including one that helps the students to learn about the “how we know what we know” and one that is perfect for the “uh-oh I’m out of time, what do I do” moment near the end of the semester.  I look forward to discussing my activities with you in an upcoming coffee break!  I would love to hear your thoughts about class activities as well.  The coffee break will be held Thursday, December 1, 2022, at 3pm EST.  You can sign up to join us here.  If you are reading this after the fact, you can get a link to the recording by reaching out to astronomy@wwnorton.com.  Don’t forget to bring your favorite afternoon beverage and I look forward to seeing you on December 1st!

-Sandi Brenner, Bryant University


JWST Carina Nebula

an undulating, translucent star-forming region in the Carina Nebula is shown in this Webb image, hued in ambers and blues; foreground stars with diffraction spikes can be seen, as can a speckling of background points of light through the cloudy nebula

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth

The Carina Nebula is a nearby (about 7,600 ly away) star-forming region, and this image captures just a segment of it. Above the image (out of frame) are a number of hot, young stars, producing outflows that are blowing around the dust and gas, carving out a cavity. This image captures the edge of that cavity, at the boundary between the thick dust and the partially-evacuated region.

I particularly like to point out “fingers” in the dust, which so nicely show which way the stellar winds are blowing. These fingers are dust shadows behind denser regions from which stars can form.

NBC News put together a particularly nice comparison of this image with the same image taken by HST (https://www.nbcnews.com/data-graphics/compare-photos-nasas-james-webb-space-telescope-hubble-space-telescope-rcna37875). By moving the slider back and forth, you can see how the infrared observatory sees through the dust to the underlying (newly-forming!) stars. More detail is evident in the JWST image as well, due to Webb’s increased aperture. It’s a beautiful example of how observations from telescopes operating at different wavelengths can complement each other. While the registration of the two images is not exactly perfect, it’s close enough to compare subtle details between the two images. One not-so-subtle detail jumps out that could be used to spark class discussion: near the center of the JWST image is a bright yellow star with prominent diffraction spikes. Slide the slider across to see it in the HST image, and you’ll know if your students are paying attention or not…

Supporting material in the texts and online: This image provides a great opportunity to talk to students about why astronomers use telescopes that observe at different wavelengths to explore different parts of the universe. You might reference this image in the chapters on Telescopes, Star Formation, or the Interstellar Medium. Other connected material appears in:

Process of Science Assignment: Interpreting Radiation through ISM

Astronomy in Action Video: Emission and Absorption

Learning Astronomy by Doing Astronomy Workbook, Activity 22: The Stuff Between the Stars will help students interpret what they see in this image, while Activity 7: Light and Spectra will help them understand the pairing of telescope and target, and why this region is a good target for JWST


JWST Southern Ring Nebula

side-by-side views of Southern Ring planetary nebula as seen by Webb telescope (NIRCam, left; MIRI, right) against black backdrop of space; a bright star appears at center in both images, surrounded by an undulating ring of gas

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-captures-dying-star-s-final-performance-in-fine-detail

The Southern Ring Nebula is a striking example of a bipolar planetary nebula, seen very nearly along the axis. Planetary nebulae result from the death of low-mass stars, and their shaping mechanisms have long been somewhat mysterious. In this image from JWST, a binary system is visible at the center of the nebula, which may provide the shaping mechanism for this object. Comparison with the HST image show that the binary star at the center was invisible before JWST took this image.

Most of the carbon in their bodies once passed through a planetary nebula like this one, as the carbon was lost from the star that fused it. Later, that carbon wound up in the cloud from which our solar system formed, so these objects have a personal relevance to our own existence.

The colors in the JWST image are not “true-color”, and this is perhaps a good image to show to initiate that conversation--why do astronomers make the color choices they do, and do the colors actually mean anything at all? (Sometimes it’s just because the person making the image liked those colors…but yes, the colors still have meaning.)

Supporting material in the texts and online: This image provides a great opportunity to talk to students about why astronomers use telescopes that observe at different wavelengths to explore different parts of the universe. You might reference this image in the chapters on Telescopes, or the Interstellar Medium. Other connected material appears in:

Exploration: Evolution of Low-Mass Stars

Process of Science Assignment: Low mass life cycle

Interactive Simulations: H-R Diagram

Astrotours: H-R Diagram

Learning Astronomy by Doing Astronomy Workbook, Activity 21: Understanding the Evolution of the Sun explores the life and death of low-mass stars.


JWST WASP-96 b Spectrum

a spectroscopy chart for exoplanet WASP-96 b with a best-fit line in blue set against an illustrated background of an exoplanet; the chart has peaks associated with H2O in the composition of the exoplanets atmosphere

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-steamy-atmosphere-of-distant-planet-in-detail

I freely admit that my mind is blown any time anyone presents any data that shows anything definite about the atmospheres of exoplanets. I (wrongly) predicted that we would not see this in my lifetime, and I could not be more delighted to be wrong.

The first JWST exoplanet spectrum came in the original release of five images, and identified water in the atmosphere of WASP-96 b. This is a hot gas giant orbiting a Sun-like star more than 1,000 ly away. The spectrum is a transmission spectrum: the planet was observed as it transited the star, and then the spectrum was compared to that of the star when the planet is not in view. The spectrum has a wide range of wavelengths, and multiple water lines are present across the full spectrum. I see other narrower lines there as well that I’m certain are being investigated further.

But already, we have more! In August, a similar transmission spectrum for WASP-39 b was released, (https://www.nasa.gov/feature/goddard/2022/nasa-s-webb-detects-carbon-dioxide-in-exoplanet-atmosphere) showing a clear detection of carbon dioxide in the atmosphere of that hot gas giant.

Graph of amount of light blocked versus wavelength of light with data points and a model, showing a broad, prominent peak labeled “Carbon Dioxide, C O 2”.

All that said, it’s a bit of a heavy lift to help students understand how exciting a graph can be!  They’ll need you to help them understand why they should be astonished that we can determine the composition of the atmosphere of a planet (even a Jupiter-sized one) from 1,000 light years away.

Supporting material in the texts and online: This image ties in to a deep fascination about life in the universe---if we are all honest about it, we are anxiously awaiting the first detection of O2. You might reference this image in the chapters on the Formation of Stars and Planets, the Giant Planets, Exoplanets or Life in the Universe.

Exploration: Exploring Exoplanets

Process of Science Assignment: Light and Spectroscopy

Interactive Simulations: Planetary Orbits Simulator and Habitable Zone

Astrotours: Atmospheres: Formation and Escape

Astronomy in Action videos: Emission and Absorption

Learning Astronomy by Doing Astronomy Workbook, Activity 6: Extraterrestrial Tourism explores the relationship between observations and properties of planets; Activity 35: Finding Habitable Worlds beyond Earth will help students understand why we are interested in the orbital properties of planets.


JWST Stephan’s Quintet

the galaxies in Stephan's Quintet appear as purple-pink swirls against the blackness of space in this JWST image; some foreground stars appear with diffraction spikes from the telescope's mirrors; numerous other galaxies and stars bespangle the image

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-sheds-light-on-galaxy-evolution-black-holes

Stephan’s Quintet is most famous for its appearance in It’s a Wonderful Life, and I really enjoy privately mulling over the absolutely astonishing improvements in imaging, physical understanding, and even humility that have occurred between the time when the image appeared in the film and the time when this JWST image was taken. However, I am not so foolish as to think that students yet enjoy that type of perspective. So, I share it with you but stick to the astronomy with my students!

Four of the large galaxies in this image are close together in space, but the leftmost one is in the foreground by about 250 million light years. The others are all about 290 million light years away. The interaction between the top three galaxies that are near to one another is extraordinary. Bright red star-forming regions really pop out in this image, as do the jets emitted from the AGN in the top galaxy. There’s a nice tidal tail to the left of that topmost galaxy, and the merging galaxies right below that topmost one really give a sense of motion and inspiral.

The background to the quintet is also interesting, with lots of galaxies of various colors, sizes and shapes.  

Supporting material in the texts and online: This image provides a great opportunity to talk to students about “What an Astronomer Sees”--how astronomers draw meaning out of an image by closely examining shapes, colors and relationships. You might reference this image in the chapters on the Formation and Evolution of Structure, because it so clearly shows that galaxies merge and evolve. Other connected material appears in:

Exploration: Galaxy Classification, where this image could be substituted for the image shown. Students can zoom in and identify galaxies of each type on a printout or grid.

AstroTour: Active Galactic Nuclei, which relates to the AGN in the top galaxy.

Astronomy in Action Video: Size of Active Galactic Nuclei and Galaxy Shapes and Orientation.

Hubble Law, where the connection between redshift and distance (of galaxies in the background, for example) is made concrete.

The Learning Astronomy by Doing Astronomy Workbook, Activity 28: Light Travel Time and the Size of a Quasar can help students understand why they can’t actually SEE the AGN at the bottom of the jets in the topmost galaxy.


The JWST Deep Field

distant galaxies appear as bright glowing spots in this Webb telescope image, with some smeared by gravitational lensing; foreground stars appear bright with six-pointed diffraction spikes, owing to the shape of Webb's mirrors

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet

Deep field images never disappoint, do they? For the novice astronomer, however, these images need quite a lot of interpretation. I usually start by identifying different types of objects in the image, and help students figure out how to identify them. The spikey objects are stars (objects like our Sun) in the foreground. These stars are bright enough that the bits of light deflected by the telescope itself are noticeable. (This is a gloss on diffraction, of course, but it’s enough for early in the semester!) A student might notice that the diffraction spikes.

The smaller, fainter objects are nearly all galaxies. This gives me the opportunity to mention what a galaxy actually is: a conglomeration of billions or trillions of stars, plus dust and gas. I’ll ask them to estimate the number of galaxies in this image, and accept any number that is in the thousands. So then I ask them to think about how many STARS are represented in this image—including the stars in the galaxies!

Next, I’ll point out that galaxies come in several shapes. I’ll point out a nice face-on spiral (there is a particularly nice one just above center on the right), and then an edge-on spiral (there are lots!). Then I’ll point out a smudgy elliptical galaxy, like the one near the center of the image.

I’ll mention that those are the two basic shapes of isolated galaxies, and then I’ll draw students’ attention to the gravitationally-lensed galaxies that appear as arcs along concentric circles around the big elliptical near the center of the image.

I’ll often ask students to notice the colors of the galaxies. At the beginning of the course, it’s too much to ask them to understand WHY more distant galaxies are redder, in general. But I ask them to notice that the galaxies shown have colors, and that distance is one of the things we can figure out from those colors.

Finally, I circle back to the most accessible big WOW of these kinds of images: a feel for the size of the universe. The image took 12.5 hours to build from lots of shorter images, and “zooms in” on a section of sky as small as a grain of sand held at arm’s length. In order to get a sense of the scale of the universe, students must imagine wallpapering the sky with grains of sand…and then replacing every single grain with an image like this one, including its thousands of galaxies.

Supporting material in the texts and online: This image provides a great opportunity to talk to students about “What an Astronomer Sees”--how astronomers draw meaning out of an image by closely examining shapes, colors, and relationships. You might reference this image in Chapter 1, as a final “zoom out” from the Figures that develop the universal address. Other connected material appears in:

The Light and Telescopes chapter, where diffraction makes an appearance (these are particularly beautiful diffraction spikes, if you are into that sort of thing!).

Evolution of High-Mass Stars, where it first becomes possible to discuss gravitational lensing.

Hubble Law, where the connection between redshift and distance is made concrete.

Formation and Evolution of Structure, which connects this image to the larger mission of JWST to find the first stars and galaxies, and finally answer these questions about how the universe has changed since very early times.

The Learning Astronomy by Doing Astronomy Workbook, Activity 32: Hubble Deep Field North is a great activity for introducing the ideas that could be explored by astronomers in the newer James Webb image.

Two related Astronomy in Action videos: Galaxy Shapes and Orientation and Expanding Balloon Universe.