Classroom Stories: Teaching in the Trailer, or "This Will Have Been a Good Time"

By Stacy Palen

In my family, we have a saying, “This will have been a good time.” We use it to refer to upcoming events that will be stressful and potentially awful, but that we will remember fondly once they have passed. For example, when my snake-phobic husband and I went to the Amazon: he didn’t enjoy the trip while it was happening, but afterwards, he was glad to have experienced it. The whole time we were planning the trip, we kept repeating, “This will have been a good time.”

For years, I have taught Introductory Astronomy in the planetarium. This is a difficult space to work in because the chairs are comfy, the light levels are low, the board and projector space is limited, and working in groups of three or more is really difficult. The chairs don’t turn; the students have those little desks that lift out of the chair arm for them to write on; and it is almost impossible to get in and out of a row in the middle of class. If I want to access the computer, I have to go to the back of the room. It’s awkward, but I got used to it, and I figured out how to do both active learning and lecturing, even in this difficult space.

This semester, the planetarium building is being renovated so that we will have heating and cooling that actually work. That’s the plan, anyway. Don’t ask me why they couldn’t do this renovation over the summer. Figuring out the decisions of Facilities Management is above my pay grade!

My astronomy class has been moved into a “portable”—a double-wide trailer in the parking lot, which was furnished the day before classes started. The layout of the classroom is awkward, with students facing perpendicular to the long axis, and the computer being stationed in one corner. It’s like teaching in a hallway. The first week of class, none of the A/V equipment was working, so there were no projectors. During the second week of class, some of the A/V equipment worked, but intermittently—something about the HDMI cables, aspect ratios, and temporary equipment being incompatible with the University standards. I don’t expect this system to be stable for at least another week or two. I could complain about this (more!), or I could see it as an “opportunity” to try something new.

So now, I have jettisoned my long-time methods and materials, and I’m experimenting. I’ve reorganized the whole class to involve lots of mini-activities that can be done quickly in larger-than-usual groups, with lots and lots of peer instruction. For my students, there is really no choice but to read the textbook before they come to class, because it’s really not possible for me to lecture at all.

Today, we’ll negotiate the “points” restructuring, and my students will get to have a say in how much weight each component will have in their final grade. Now that we’ve done a few of the longer activities from Learning Astronomy by Doing Astronomy, a few homework assignments, and a few of the mini-activities, my students have a better sense of how much value each component should have. I’ve explained the experimental nature of what we are doing, and they are mostly cheerful about it.

This entire situation has got me going back and resurrecting things that I did a long time ago, such as using parts of Understanding Our Universe and Learning Astronomy by Doing Astronomy in ways that I haven’t before (it never occurred to me to tear the activities apart and do them over multiple days), seeking out new ideas and activities, and oh … let’s call it “innovating” … at breakneck speed. I expect a lot of this to be a mess, some of it to be useful in the long haul, and some of it to appear in future textbooks. It’s definitely a situation that “will have been a good time.”


Current Events: Image Release: Giant Magnetic Ropes in a Galaxy’s Halo

By Stacy Palen

A new composite image released by the National Radio Astronomy Observatory superimposes radio data on a visual image of a galaxy. Magnetic fields here are shown in blue and green, indicating alternate directions.

Here are some questions that you can ask your students based on this image:

1) What is the Hubble type of this galaxy?

Answer: A spiral.

2) How do you know?

Answer: Because there is a disk, viewed edge on.

3) What is the Hubble type of the large galaxy directly above the primary galaxy in this image?

Answer: Elliptical.

4) How do you know?

Answer: There is no disk.

5) The blue and green false color “hair” represents the magnetic fields of the galaxy. Blue indicates that the magnetic field points roughly away from us, while green points roughly toward us. These magnetic fields are described as “spiraling” and as “ropes.” Make a sketch of the magnetic field lines of the galaxy that fits these descriptions and observations.

Answer: This is a genuine question, not a test of their understanding. I am picturing a spiral for each blue/green pair that is roughly perpendicular to the disk. I wonder what students “get” from these descriptions?

6) Are the magnetic fields above the disk of the galaxy symmetric with those below the disk? What might cause this?

Answer: They are not. It could be because the magnetic field is being generated differently, or it could be because the observations are more resolved above the disk than below. That could happen if the galaxy disk was tilted so that the top of the disk is tilted toward us.


Current Events: Probe Gets Close to the Sun—Finds Rogue Plasma Waves and Flipping Magnetic Fields

Sun nasa pic_12_20_2019
Credit: NASA/SDO

 

By Stacy Palen

Just in time for the close of the semester, we get a present from NASA! According to this article on NPR, the Parker Solar Probe has arrived at the Sun, and it’s sending us back some big surprises.

Here are some questions, inspired by the Parker Solar Probe’s recent discoveries, that you can ask your students:

1) In 2025, the Parker Solar Probe will come within 4 million miles of the Sun, which is 1/10 the orbital distance of Mercury. To date, it has passed within about 15 million miles from the Sun (almost 4/10 the orbital distance of Mercury). Make a sketch of the Sun and the orbit of Mercury, and then draw circles that show the closest distance of the Parker Solar Probe so far, and its distance in 2025.

Answer: A sketch.

2) The Parker Solar Probe has observed unexpected spikes in the flow of solar wind, where its speed suddenly increases by 300,000 miles an hour, which is nearly double its normal, steady speed. These spikes last for varying amounts of time, from a few seconds to hundreds of seconds. Convert this information into a graph of the speed versus time for an outflow over five minutes of observation. Assume that two spikes occur, one of 5 seconds and one of 100 seconds.

Answer: A graph.

3) The Parker Solar Probe may answer a question that’s been around for decades called the “solar corona problem.” From the context of the article, or from some general research on Google, describe this problem in your own words.

Answer: Why is the corona so hot?

4) The article repeatedly mentions that the magnetic field “flips” without thoroughly explaining this process. What exactly does this flipping of the Sun’s magnetic fields mean?

Answer: This means that the north end of the magnetic field switches locations with the south end.

5) Why did astronomers think that their equipment might be malfunctioning?

Answer: Because the changes in the speed and direction of the magnetic field were happening much faster than expected.


Current Events: A Missing Neutron Star May Have Been Found after 30-year Hunt

Stsci-h-p1708a-m-1823x2000
Credits: NASA/STScI

By Stacy Palen

Supernova 1987a may be the most well-studied supernova in history. But the “corpse” had not been found! However, this may have changed according to this article from Scientific American.

Here are some questions you can ask based on this article:

1) How long ago was this supernova first observed on Earth?

Answer: 30 years.

 

2) How long ago did the supernova actually occur?

Answer: 163,000 years

 

3) Why do astronomers typically not worry about the discrepancy between the times in question 1 and question 2?

Answer: We can’t know about anything that happens until the light gets here. As far as we are concerned, the moment we observe it IS the moment when it happened.

 

4) What is special about supernova 1987a?

Answer: Supernova 1987a is so unusually close that we can see it in detail, and watch it evolve in real time. It is also the first supernova observed for which we had seen the progenitor star.

 

5) Why had astronomers argued that a neutron star (as opposed to, say, a black hole) should result from this supernova?

Answer: The progenitor star was about 20 solar masses. This is in the range between 8 and 25 solar masses, which is expected to result in a neutron star.

 

6) What is the evidence that has been presented for the detection of a neutron star?

Answer: A bright blob within a dense dust blob.

 

7) What will astronomers do to strengthen their conclusions from this evidence?

Answer: Get more data, of course!


Classroom Stories: Practice at Being Afraid

By Stacy Palen

In my other life, I train horses and riders. This means that I routinely deal with actual life-threatening situations like runaway horses and bad falls. Even non-life-threatening situations such as broken bones, giant bruises, bumps, cuts, and scrapes can seem routine to me but be scary for others.

Because of this background, I sometimes struggle to really understand and empathize with students who literally fear math and have an obvious physiological response to being asked to do it.

Recently, I came across a Facebook post by equestrian Denny Emerson about fear that helped crystallize my thoughts about this.

Two things you should know about Denny: First, Denny is as famous in the horse community as Tom Brady is in football. Second, his sport is more dangerous than most horse sports, as the horses race cross-country on uneven ground over solid fences that don’t come down. It’s not unheard of for people to die doing this sport at the highest levels.

Here’s part of what he had to say:

 

But we all experience things that create the exact flight or fight response as actual extreme danger that are not actually dangerous.

Case in point----Denny Emerson, age 9, is cowering in Miss Gibson's Four Corners School 4th grade math class, trying to remain invisible, as students are handed a piece of chalk, and asked to solve problems on the black board, in front of the whole class. As his name gets called, Denny is suffering the agonies of the damned, just as if he was about to be hurled into a pit of writhing cobras.

Which is another way of pointing out that the fear we so often experience is not actually in direct proportion to the danger we are in, but it feels that way.

So, then, it follows more or less logically, that one way to alleviate being paralysed by fear is to avoid, if possible, real danger, and to try to become better prepared to face challenge that only feels like true danger. Like arithmetic.[1]

 

Denny went on to talk about how to condition yourself and your horse to deal with fear, but I made a note in my mind of what he had to say here.

It resonated with me because a week or so before that, I heard the familiar whine of “When am I ever going to use this in real life?” from one of my students. (I refrained from pointing out that she was in astronomy class…practicality isn’t really the point.)

Denny’s answer is one that I’ve tried to articulate for a long time, and one of the best that I know: “it’s practice.”

Mathematics is not actually dangerous. AT ALL. But for some students, it feels that way.

Good. That makes it an opportunity to practice being afraid while holding it together and getting the job done anyway.

It’s practice at a tool they need in order to find success in the world.

Come to think of it, this may have been what my parents meant when they told me to do hard things I didn’t like because “it builds character.”

I probably won’t tell my students that—it sounds a lot like a curmudgeon's “get off my lawn” rant. But I may spend some time talking to them directly about how this practice can help them in other adrenaline-laden situations.

 

 

[1]Emerson, Denny. Tamarack Hill Farm Facebook Page. “More thoughts about fear, and how to live with the reality of fear without being a slave to fear” Facebook, November 23, 2018. https://www.facebook.com/permalink.php?story_fbid=10155572672270947&id=109161715946


Current Events: Moonrise at Sunrise

Moonrise
Credit: NASA/Christina Koch

By Stacy Palen

The image above was taken from the International Space Station by NASA astronaut Christina Hammock Koch and could form the basis for a nice final exam question.

 

1) In this image, what is the phase of the Moon? How do you know?

The moon here is a Waning Crescent. The image was taken looking East, into the sunrise, so north is to the left in this image. Therefore, the Moon is “leading” the Sun across the sky and illuminated on the eastern half. This means it is in the Waning phases.

 

2) If you had only this image to go by, with no caption, how would you know that it was an image of Earth?

The planet shown has a solid surface and a shallow but significant atmosphere. Earth is the only terrestrial planet that fits these criteria.

Other potential answers:

  • It could not be Venus or Mercury because neither planet has a moon.
  • Mars’ atmosphere is too thin to refract blue light in this way.
  • There appears, possibly, to be a hint of colors other than red on the surface.

 

3) Based only upon the image, would you think this planet might be a good place to look for life? What other information could you gather from this viewpoint that would make you more certain of your conclusion?

This planet may be a good place to look for life. The solid surface and the presence of an atmosphere would make me want to investigate further. I would especially want to get a closer look at the surface, or get a spectrum of the atmosphere in order to be totally sure.


Reading Astronomy News: ESO Telescope Reveals What Could be the Smallest Dwarf Planet yet in the Solar System

Eso1918a
ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS)

By Stacy Palen

According to this article by the ESO, Hygiea has been imaged by ESO’s VLT. It is round, which makes it a dwarf planet rather than an asteroid. Smaller than Ceres, it is now the smallest known dwarf planet in the Solar System.

 

1) Study the image of Hygiea at the top of the article. The image of this tiny object is a little bit fuzzy, despite the powerful telescope used to obtain it. Nonetheless, some features are visible. Describe the surface of Hygiea.

Hygiea appears to have some craters, with variations in height as well as variations in brightness.

 

2) Until this image was taken, astronomers were not sure whether to categorize Hygiea as an asteroid or a dwarf planet. Which criterion for dwarf planet status could be determined from this image?

Hygiea has enough gravity to pull itself into a round shape.

 

3) The article compares Hygiea’s size (430 km) to that of both Pluto (2400 km) and Ceres (950 km). Roughly how many times larger are these other dwarf planets than Hygiea?

Ceres is a bit more than twice as large, and Pluto is about six times larger.

 

4) Describe the origin of this dwarf planet, in your own words.

A much larger planetesimal collided with a smaller one about 2 billion years ago. The explosion created 7,000 asteroids, at least one of which had enough gravity to form a dwarf planet.


Classroom Stories: Vera Rubin Tells The Story

Dark Matter
Image credit: NASA/JPL-Caltech/ESA/Institute of Astrophysics of Andalusia, University of Basque Country/JHU

By Stacy Palen

I was poking around, looking for something completely different when I came across this nice little vignette from "Physics Today" published in 20061. It’s the story of the discovery of dark matter, told by Vera Rubin herself.

The story is mostly accessible to introductory students, with only a little bit of stretch required in the single paragraph that describes circular velocities and flat rotation curves. Hilariously, she includes an "exercise for the reader.” (Well—hilarious to me, and probably you, but students won’t get it.)

If your students have already learned about galaxy rotation curves, they will be able to follow the paragraph. If not, it’s fine if they skim over it—they won’t lose the plot.

The descriptions of observing at the telescope, and the trouble of moving the spectrograph from one location to another really gives a nice feel for how hard it was to get this done the first time.

I’m not entirely sure what I’m going to do with this story in my classes yet, but I found it charming, and think it will capture the interest of some of my students who struggle to connect to this material. I’ll at least share it with them through the LMS so that students who are interested can read it.

If you come up with a plan to use it, tell me about it in the comments!

                

1 Unfortunately, the biographical information published with the article is out of date. Vera Rubin passed away at the end of 2016.


Current Events: Naming the Moons of Saturn

By Stacy Palen

I long ago stopped keeping track of the number of moons around Saturn and Jupiter. It often feels like there is a contest going on among astronomers—who can find the most moons around “their” planet! In early October, a report hit the news of 20 new moons discovered around Saturn, many of them in retrograde orbits.

This brings the number of moons around Saturn to 82. The number around Jupiter? Only 79. Neener-neener, Jupiter devotees!

Seriously though, if you are now discussing moons, planets, or planetary formation, this is a timely discovery to talk about with students. Or if you are about to start talking about dark matter, it may be a good time to remind students about Keplerian orbits and Newton’s version of Kepler’s Third Law.

But wait! There’s more!

These moons are not yet named, and Scott Sheppard has decided to have a contest to name them all.

Here are the general rules from the Carnegie Science website:

https://carnegiescience.edu/NameSaturnsMoons

  • Two of the newly discovered prograde moons fit into a group of outer moons with inclinations of about 46 degrees called the Inuit group. All name submissions for this group must be giants from Inuit mythology.
  • Seventeen of the newly discovered moons are retrograde moons in the Norse group. All name submissions for this group must be giants from Norse mythology.
  • One of the newly discovered moons orbits in the prograde direction and has an inclination near 36 degrees, which is similar to those in the Gallic group, although it is much farther away from Saturn than any other prograde moons. It must be named after a giant from Gallic mythology.

Full details are available on the website along with a link to a list of names already used and a little video that describes the contest.

It would be great fun to make a class project or competition (even for college students) to choose a name to submit as a group. It’s the kind of experience that students remember for a long time. Submissions are due via Twitter by December 6.


Reading Astronomy News: Giant Radio Telescope in China Just Detected Repeating Signals from Across Space

A74YFG
Stocktrek Images, Inc./Alamy Stock Photo

By Stacy Palen

Fast radio bursts have been known since 2007. Recently, China’s FAST telescope has detected a repeat of one first discovered at Areceibo in 2012. This article poses several explanations for fast radio bursts.

Questions:

1) Study the picture of the 500-m telescope at the top of the article. Is this a “steerable telescope?"

Answer: No, this telescope is far too large to be steerable.

 

2) Describe how a telescope that is not steerable “sees” the sky differently than a steerable telescope.

Answer: A telescope like this can see only the portion of the sky that passes through its zenith. Because it is not steerable, it cannot track an object, so the observing time is set by the amount of time it takes for the object to pass through the field of view.

 

3) The signal was emitted from a source 3 billion light-years away. How long has the signal been travelling to reach us?

Answer: The signal has been traveling for three billion years.

 

4) What was happening on Earth when this signal left the source?

Answer: The earliest forms of photosynthesis date from around this time.

 

5) Why is a repeating FRB so interesting to astronomers?

Answer: If the FRB repeats, that rules out a whole class of causes. The object has clearly not blown up, so this is not connected to supernovae or black hole mergers.

 

6) Choose one of the proposed explanations for FRBs and explain in more detail how an FRB could be caused in that way.

Answer: Answers will vary.