Current Events: Moonrise at Sunrise

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

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:

  • 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

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.


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.

Current Events: Supermoons and Other Nonsense

Credit: NASA/Bill Ingalls

By Stacy Palen

In July 2019, I received a few queries about a “black supermoon.” Since I had no idea what that was, I decided to track it down. It comes from a group of click-bait articles like this one, which are apparently taking off from a random article in Travel And Leisure magazine.

In brief, there is a new moon. It’s the second one in a month. Apparently, the Farmer’s Almanac calls this a “black moon.” This new moon occurs at perigee, when the moon is closest and has a (technically) larger angular size.

This has lately become known as a “supermoon.” The astute reader will note that you can’t even see this supermoon because it's a new moon. (Cue GIF of Kermit the Frog flailing his hands wildly in despair.)

In the last few years, “supermoons” of various kinds have suddenly become news.

A quick query of Google’s Ngram Viewer reveals that the word isn’t even in their database up through 2008, which is somewhat reassuring; it certainly feels like the term suddenly started popping up just a couple of years ago! But this was the first I had heard of a “black moon.”

Why does this matter? More astronomy in the news is better, right? Well, sort of.

Suppose everyone gets all excited about going out to observe the “black supermoon” and it’s nowhere near as interesting as they expect. Thereafter, they are less likely to follow up when something truly exciting happens, like the total solar eclipse that is coming to the US in 2024. (Have you made your plans yet? I have.)

Competing for the attention of the public, at this point, is a remarkably difficult prospect. I see why some outlets would seize on the popularity of astronomy to try to get a few seconds of that all-important attention. But in the long run, this is a failing strategy if the “news” fails to deliver what it has promised.

This particular article provides a good opportunity to help students see when they are being “click-baited” since there is literally nothing unusual happening.

A student who really understands the lunar orbit and phases of the moon will react to this article much like Ralphie in A Christmas Story, when he receives his Little Orphan Annie decoder ring and realizes the whole thing is a marketing ploy.

“A crummy commercial?” he exclaims as he throws away his long-awaited prize.

Given the last few years, I expect to see two or three articles like this over the course of the next academic year. Each time a student (current or former) asks about it, I will use it as a “teachable moment” and recommend that they fully engage their baloney detection kit when reading their news feeds!

Classroom Stories: Psychology and Underrepresented Groups

C98R91 (1)
B.O'Kane / Alamy Stock Photo

By Stacy Palen

This week in Physics Seminar, we had a psychologist come and talk to us about a number of studies that indicate how stereotypes impact the performance of underrepresented groups. Generally, this refers to women and minorities (although other categories also intersect). The take-home message is that when underrepresented groups enter an environment in which they are the minority, they show a physical autonomic nervous system response. Really—heart rates and sweaty palms and all!

Dealing with this “fight or flight” response taxes their working memory, and they do not perform as well. Several other cleverly designed studies have investigated “stereotype threat” and have shown that when the stereotyped group is engaged in a task in which they are stereotypically bad, they are extremely sensitive to signals that confirm the stereotype.

For example, these groups will have a stronger negative reaction to a poor score on a first exam, and they are more likely to see that score as a signal that people like them are not “meant” to study science.

This is all very fascinating, but the speaker went further and gave us some concrete examples of specific interventions that help level the playing field. Interventions such as in-class discussions about the contributions of women in science may be obvious, but others were less obvious.

For example, one study had women engineering students wait briefly in an office full of items that evoke the male stereotype of an engineer (Star Trek posters dominated by male faces, gaming consoles, piles of soda cans, etc.). A second group waited in a very similar office which had slightly different posters (still science fiction, but less firmly associated with the male stereotype). This room also lacked the pile of soda cans and had an abstract picture of a flower on the wall.

Shockingly, the difference in performance on a subsequent math test was statistically significant, with the women who waited in the stereotype-evoking office performing more poorly. (Men’s performance was not affected.)

Astronomers are lucky. We have lots of examples of a diverse population contributing to our understanding of the universe. Highlighting those examples has been shown to improve performance by those who identify with the specific groups mentioned.

Conversely, highlighting the accomplishments of the majority group negatively impacts performance for the underrepresented group.

Interestingly, the majority group is not impacted in either case because they are not carrying the distracting mental burden of stereotype threat into the classroom!

The take-home message of these kinds of studies is that no matter how well the test instrument is designed, and no matter how much or how well the student knows the material, there are external factors affecting performance. These factors can be lessened by specific (small) interventions, like hanging up a different poster, highlighting diverse scientists, or intervening after an exam to point out that “this material is hard because it’s hard, not because you aren’t good at it.”

Kids in the Classroom


By Stacy Palen

I teach at an open-enrollment university with a very large number of non-traditional students: nearly all of my students have jobs with large time commitments. Many of them are parents of young children. More than half of them are married.

This semester, something interesting has been happening that has not happened before and it started with just one student. I suspect that the time of the class has something to do with this as it’s at 2:30 in the afternoon, rather than in the morning or evening when I typically teach.

A young mother, in the first week of class, emailed me to let me know that she was having trouble with her child-care arrangements for her 9-year-old daughter, and she wouldn’t make it to class. And also to ask if we were we doing anything “important” that she would miss. LOL. Fortunately, I received this email in advance, and was able to suggest that she just bring her daughter with her. So she did. And her daughter was quiet, but attentive, and even “took notes” on a sheet of paper. She even asked a good question!

So then another young mother, in week four, asked if she could bring her daughters to class, for a similar reason. These two are 8 and 6. Both sat and listened quietly. The 8-year-old raised her hand to contribute to the conversation. Her comment was not entirely on point, but she was brave to do it, and I didn’t mind.

This past week, in week five, I’ve had another bring her daughter to class. I don’t know her age, but she looks to be about 12. This young girl also sat quietly, was not disruptive, and then came to ask me a few questions after class.

This week, the first mother came to see me, and now the 9-year-old who started it all, will be coming to class every other week on Wednesday, which solves a complicated co-parenting problem for her mother, and enables the mother to come to class on those days.

Other students in the class have reacted really well to this, and I think it puts them on their best behavior a little bit, when the little kids pay attention, focus and ask questions. I suppose it’s possible that I may wind up with a class half full of little kids, but actually think that’s unlikely. The mothers have always asked permission, and are very much aware that their kids could be disruptive. It’s probably a little distracting for them, but better than not being in class at all.

This week in Physics Seminar, we had a psychologist talk to us about ways to make STEM fields less intimidating for women. I suspect this is one of them; being a little bit flexible about accommodating the complicated lives of students with multiple obligations.

I’m interested to see how this develops as the semester continues…

Reading Astronomy News: Our Galaxy’s Black Hole Suddenly Lit Up and Nobody Knows Why

Image credit: NASA/JPL-Caltech

By Stacy Palen

Sgr A* is flaring to twice peak historical levels, possibly because of gravitational disturbance from S0-2. This particular article from Vice News provides a good opportunity to help students see when they are being “click-baited,” since “Nobody Knows Why” is a bit of a tease. There are actually several explanations for why this might happen, as the article later explains.


1) “Flux” may be a new vocabulary word, particularly in this context. Look it up and summarize the definition that is relevant to this article in your own words.

Flux is the light emitted per second per square meter.


2) The article states that we have been monitoring Sgr-A* for about 20 years. What technological improvements made a monitoring campaign like this one possible?

We needed to be able to observe in the infrared at high enough resolution to avoid confusion of sources in this tightly packed region of the Galaxy.


3) What possible causes for the flare are given in the article?

A close pass of SO-2 may have disturbed the gas near the black hole. We may be seeing a delayed reaction from a dust cloud that passed by and was torn apart.


4) Notice the article’s title: “…and Nobody Knows Why”. Do you think that this is an accurate characterization of what astronomers know about this flare? Why do you think the article’s title was written in this way?

Answers will vary for the first question; the second answer should include something about baiting people to click on the story.