The Classroom Astronomer Newsletter #2 - June 1-15, 2021

Astronomy Education Articles, Teachniques, Research

The Classroom Astronomer Newsletter is a successor to the magazine of that name that ran from 2009-2015 which contained articles and teaching tips for those who teach astronomy in schools at all levels, including home-school teachers.  This newsletter is free during an introductory launch period after which is will be a premium newsletter for subscribers only. 

During the past week I have been attending (virtually) the Communicating Astronomy to the Public (CAP) international conference! Tons of stories to bring to you, and this issue has just a few!

I am Dr. Larry Krumenaker, a long-time astronomer writer and educator.  Welcome to my Universe!

In This Issue:

  • Connections to the Day Sky

  • Astronomical Teachniques

  • The RAP Sheet – Research Abstracts for Practitioners

  • The Galactic Times Newsletter Highlights

Connections to the Day Sky

Here comes the Solstice. On June 21st, six days after this Issue’s end date, the Sun reaches its maximum distance north in the sky and north of the Earth’s equator. Historically, this is when Eratosthenes supposedly observed that there was no shadow in a vertical well in Syene (now Aswan), Egypt, but there was one in Alexandria. That could only happen if the Earth was a sphere (or at least curved). By measuring the distance between the two sites, and the angle of the Alexandrian shadow, he could determine how much of the curve was between the two sites, and therefore the size of the Earth.

At the CAP meeting I saw a short presentation by Andy Newsom of the United Kingdom’s National Schools Observatory that had a very interesting variation of this that was performed all through the UK on less than a week’s notice, as an experiment in trying to reach pandemically homebound students, particularly those in lower socioeconomic strata.

What was unique was that he found a way to do this with just one measurement! It involved a bit of a cheat, but I found a better justification, and a way to do it on ANY day. His methods, with one stick or two sticks (i.e. collaboration, also a useful scientific skill) then could be used statistically to show graphing and uncertainty determinations. Both methods gave good and fairly accurate values for the circumference of the Earth.


His method is astonishingly simple. Use any good straight stick—a ruler, a meter stick, a rod (as long as you have something to measure it with)—or any straight vertical something, including a wall edge shadow, or a child him- or herself!. Have it/them stand vertically on a sunny day within a few days either side of the actual solstice, and

[The angle from feet to top of head to the shadow of the top of the head is A.]

at 1PM if you are on any kind of daylight savings time (noon otherwise). We are ignoring any distance from your time zone central meridian, though you COULD increase your accurately slightly by constantly measuring your stick’s shadow length every few minutes to find its exact smallest length, for a half hour on each side of the hour. You need to end up with the height of your stick and the length of the shadow, preferably in cm or mm for increased accuracy.

There are three angles involved. The shadow starts at the bottom of the vertical stick; they make a 90 degree angle there. You want the angle the top of the stick makes when you connect it to the end of the shadow, measured from the stick, not from the ground, i.e. the angle in the air at the top of the stick not touching the shadow. Call it A. The equation is simple. The Tan(A) = shadow length/stick height. Make sure you count only the part of the stick above ground! Find the arctangent of the value to get A (in degrees).

Here is the cheat, sorta. Supposed you only have your own measures. But you know where you are and you know your planet is curved and you can use Polaris or a sextant or whatever to get your latitude. You also know that on the Solstice, the Sun is over the Tropic of Cancer and intrepid explorers have found that to be at latitude 23 degrees 27 minutes (23.45 degrees). In doing so, we know that one degree of latitude is 69 miles because when they or you went south to visit a friend one degree latitude away, you were that far distant.

So…as an example, my latitude is 32.43 degrees. Take the difference between A and 23.45 degrees. On the solstice, my Sun will shine just 8.98 degrees from the vertical of my gray haired head. (I’ll check this on this solstice….)

That means I’m 8.98 x 69 = 619.62 miles from the Tropic of Cancer. I’m also 8.98/360th of the way around the Earth, so that gets me a circumference of 24,784 miles, about 1% off.


You can do this one-stick method any day where you know where the Sun is, which means any solstice or equinox, making it a good September or March activity in school as well. You can use a two-stick version ANY day, because then you only need to know the north-south distance differential on that day, and the Sun’s sky position/overhead on the Earth position is irrelevant.

For more information on the UK experiment, go to [All illustrations courtesy Andy Newson and the UKNSO.]

[Check that the solstice occurs on time with the Hermograph Sundial T-shirt!]

Astronomical Teachniques

  • When is the Milky Way not a candy bar? When it is a cinnamon roll!

Yes, a simple way to answer the question, how do we know the galaxy is a spiral when we don’t see it that way from the Earth, is to get a nice spirally cinnamon roll or bun and show it with a nice summertime photo of the Milky Way, and then rotate the bun until it is horizontal, edge on. You might add a yellow gumdrop or other confection a bit inside the bun to represent the Sun’s position, and maybe food color in a dust lane around the mid-point of the circumference.

  • Tactile Printing—Not Just for the Blind Anymore

It used to be that doing inclusive astronomy for the visually impaired meant doing large flat printings with braille lettering and some slight positive or negative impressions in the large papers, representing stars or planetary features or the Milky Way clouds on a map of the sky. No more. Welcome to the world of 3D printing!

A powerpoint presentation at CAP and an article came to my attention on this technique. The presentation, by a large group of Indonesian educators led by A Z Rossykin and 8 others, were printing in plastic all sorts of 3D artifacts, in astronomy and other sciences. The picture below shows unpainted versions of the Moon, Earth, Mars, Saturn, and Earth features like a full scale hurricane. They noted the printer cost them over $100 and each object cost $10-15 in plastic.

[credit Rozzykin et al.]

The article was from the Smithsonian Institution and concerned both 3D virtual reality images of supernova remnants, but also 3D models of these, all from the Chandra space telescope. You can use the video clips on the site as well for instructional purposes. Find them and a full list of available Chandra 3D objects, along with information about how to view and print, at

The RAP Sheet – Research Abstracts for Practitioners

What’s in the scholarly astronomy education journals you can use NOW.

“The Curious Construct of Active Learning,” Doug Lombardi1, Thomas F. hipley, Astronomy Team, Biology Team, Chemistry Team, Engineering Team, Geography Team, Geoscience Team, and Physics Team. Psychological Science in the Public Interest, Vol. 22(1) 8–43. (2021). DOI: 10.1177/1529100620973974

Most teachers of astronomy are aware of the term “active learning” but even so, ‘lecture’ still can be stubbornly pervasive. As the authors state, “Active learning involves instructional strategies that allow students to work independently or in small collaborative groups to learn or reinforce content. Having students engage in actively constructing their understanding (often in a social setting with their peers) is ultimately more effective than having them passively listen to the instructor tell them what they should understand.” What this article attempts to do, in a wide variety of science fields, not only astronomy, is to develop a framework, definition, and status report of what active learning IS overall and in these different fields.

In this review, only the astronomy aspects are examined.

First off, the authors found that in astronomy education research, ‘active learning’ is commonly referred to but it is frequently not actually defined and in formal studies even a theoretical framework is not mentioned. For a practitioner, this isn’t of much concern. Active learning makes students more interested, more engaged in your classes; these likely are not going to become future astronomers, though they might become future science teachers. As a teacher, you want your students to be more scientifically aware and literate.

Second, unlike in some fields (say, nuclear physics), often astronomy course students have the ability in astronomy courses to collect real data and analyze it. The authors note these can come often not from campus facilities but from robotic or remote telescopes, such as the Global Telescope Network (, the Faulkes Telescope Project (, or the MicroObservatory Network ( Yet, these CUREs, course-based undergraduate research experiences, were found to provide improvements in students’ perceived confidence in participating in science but no clear increase in understanding of science practices.

What kinds of active learning experiences do they find in astronomy? They note five.

Astronomy, often parallelling physics education and its uses of active learning, uses lots of models and astronomy is high on using simulations for its models. “The bulk of research around models in astronomy,” the authors write, “has focused on the efficacy of individual simulations or simulation types. For example, Ruzhitskaya and Speck (2011) created a simulation of stellar parallax and found that students who engaged with it had higher posttest scores than those who completed a similar, paper-based activity.” Another activity is flipped classrooms. These task students with listening to lectures at home and solving problems during class and, the authors report, have shown notable improvements in students’ learning over traditional lecture-based courses. Peer instruction has been adopted in astronomy, too. A third method—lecture tutorials, involves a short lecture on a topic followed by 10- to 20-minute tutorials exercise among students in small collaborative groups. These tutorials are a sequence of questions that supports the students’ discussion on the topic, and often include artificial debates that force the students to check their conceptual understanding. A final somewhat related ‘active learning’ type of activity in astronomy is the ranking task—four to eight diagrams with variations of a basic physical situation that require students to collaboratively order or rank them on the basis of specific features. such as six phases of the Moon at various locations in the sky.

Numbers were not mentioned much, at least in astronomy, in the article. The net result, one quoted study found, was that in astronomy, students who engaged in structured peer activities (i.e. active learning) performed 20% above those who received lectures alone. Which means at least one grade level rise, say a D to a C, and if the numerical grade is high enough, say a high C, it just might squeak the student to a low A.

Whew! Like teaching, writing the Newsletter means we need a coffee a break! Buy us a coffee at:

our Galactic Times/TCA Patreon site!

In The Galactic Times Newsletter:

  • Astronomy News
    New Mars probes and what is still operating there; Where are giant planets located?; Meteor showers everyday!

  • Sky Planning Calendar
    Moon and planets for the two weeks; The Ring and Partial-for most of us-June 10 solar eclipse on June 10.

  • The Galactic Times Podcast — Exoplanetary Music

Subscribe to it here! It’s Free!

Back Issues of the original The Classroom Astronomer magazine, with articles, Teachniques, Activities (all still perfectly good today!), Article Index on the Web, Tables of Contents all still available for purchase in PDF format, at the Classroom Astronomer homepage.

Coming Soon!

Learning Astronomy Under The Northern Stars – A 365-Night Per Year Textbook

Use the stars that are ALWAYS visible to understand basic astronomy, stellar evolution, galactic structure, with the naked eye and common binoculars.  EBook (late spring) and print book coming (summer).  Detail description and advance orders coming soon.

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Thanks for visiting our Universe! Stay safe in yours!

Questions, suggestions, comments? Email them to:
Dr. Larry Krumenaker
Twitter: @ToTeachTheStars Facebook: Hermograph Press

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