The Classroom Astronomer Digest for October 2022
Four Sky Lessons, Three Teachniques, One Connections, an Outreach Survey Result, an Online Sky Calendar, and Changes to Future TCA's and a New Publication, The Galactic Times InDepth
Cover Photo - Passage of Moon Through Shadow
In This Issue:
(Stories are truncated to fit the Digest)
Cover Photo - Passage of Moon Through Shadow
Welcome to The Classroom Astronomer October 2022 Digest Issue!
- Changes to The Classroom Astronomer
- A New Publication, The Galactic Times—InDepth- The Galactic Times Online Sky Events Calendar
Sky Lessons -
- Education With the November Total Lunar Eclipse
- Stellar and Planetary Brightness Differences
- Meteor Radiants Aren’t Stationary- What Kinds of Questions Can You Get from Making Craters from Meteors?
Astronomical Teachniques
- When The Sun and Moon Look the Same Size, How Big Is a Shadow?
CAPping off CAP: Reporter’s Notes:
- - Not All Color Graphics Are Equal
- - A Cosmic Partnership - A University-Library Cooperative for Caregivers and Children 4-7 Years OldPerceptions of Outreach - Results of a Survey
Connections to the Sky
- Pluto In Crisis, Using Characters to Teach Astronomical Concepts
Welcome to The Classroom Astronomer Digest for October 2022
The Classroom Astronomer, and also The Galactic Times, will undergo the changes following this issue’s publication:
1. The free TCA Digest will cease with this October 2022 issue. Instead, free TCA subscribers will get one free regular issue each month, usually containing the popular Sky Lessons articles, the Connections to the Sky briefs about resources, and some of the Astronomical Teachniques, generally those that pertain to K-12 students and some public outreach programming. The regular, premium TCA issues will contain most of the conference reports, most of the Astronomical Teachniques, and articles related to college, planetarium and other museum-venue outreach programming, plus the RAP Sheet summaries of the roughly 30+ scholarly journals we monitor for classroom-usable astronomy education research. Longer, specialized articles that TCA occasionally does will go into the appropriate issue. Premium subscribers will get BOTH types issues each month. It pays to go premium!
2. The Galactic Times, which is free, is expanding to include a second publication, The Galactic Times—InDepth. This will be a monthly premium-level publication, beginning early November, featuring deep dives into an astronomical topic or story, at a New York Times Sunday Magazine length and level.
The first issue’s story is entitled Space Tourism on Earth and simulates a future tourism trip to a lunar crater by visiting the 5-6 mile diameter Wetumpka, Alabama meteor crater. Three driving trails with stops are outlined with maps and photos.
Future articles include a Star Trek astronomy-derived story and a piece on Polaris and the true North Celestial Pole today. Other anticipated issues include interviews, conference plenary derived works from science and education-based conferences, and more, at a depth that otherwise would take several TGT issues to do.
All TCA subscribers WILL get an email invite to subscribe. The initial subscription is $18 per annum, or $5 for individual issues. Each issue will contain a download link to a PDF file. It is hoped that you will enjoy this new publication!
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Since it is always good to know what’s going up in the sky, we have installed an online Calendar of (mostly) Sky Events on our sister publication The Galactic Time’s homepage, www.thegalactictimes.com . The material origin is mostly from the Sky Planning Calendar of TGT, some of which is often enlarged into TCA’s Sky Lessons column. The calendar can be imported into Google Calendars and others! Here is an illustration of the text version of the calendar, which you can reach at the above web address, then choosing the the leftmost menu choice, and from its drop down menu, choosing its last option.
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Finishing up our reporting of the Communicating Astronomy with the Public (CAP) conference in Sydney, I also add in a report on outreach as seen by the AAS Division for Planetary Scientists (DPS). This issue includes a look at a program in the UK where a university partnered with libraries in low-income neighborhoods to improve attitudes with both kids and caregivers about STEM, and two looks at making sure both your graphics and your instructional videos have images and storylines that don’t confuse the issues that you are trying to teach.
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Key websites: Homepage for The Classroom Astronomer, with its index to all Inbox Magazine issues’ contents, by celestial object, educational subject area, grade level or venue, and with complete Tables of Contents:
https://www.classroomastronomer.com . Not a Full Paid Subscriber? Become one by upgrading with our 45% off Upgrade rate! Click the button below (and then you’ll have access to the Archive of all past issues!).
The ultimate home of our Universe — Hermograph Press — has its homepage at: www.hermograph.com and its Store, for educational materials and books, at: www.hermograph.com/store .
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Thanks for subscribing!
Publisher -- Dr. Larry Krumenaker
Sky Lessons
- Education With The November Total Lunar Eclipse
Total lunar eclipses are slow, grandiose, colorfully red or even dark black, and to many person’s surprise, educational. And if you want to take part in the latter, the upcoming November 8th lunar eclipse is your last best hope…..for the next 28 months! The next lunar eclipse…anywhere on Earth…won’t be until March 2025. There will be some partial and penumbral eclipses, but total? There’s a total lack.
First, the Basics…
November 8th’s total lunar eclipse has an hour and a-few-seconds-shy-of-26 minutes of totality. To see all of the eclipse, total and partial, though, you have to be on the North American Pacific Coast, west of a line starting at the Arizona-New Mexico border to the North Dakota-Minnesota border. Or, be in Japan or Eastern Russia. East of that mentioned North American line it will be visible only in part. In fact, the Moon will set during totality if you are east of a line from Lake Michigan to the Texas Gulf Coast. Between the two lines, you’ll see totality but not all the partial phases.
Sample times:
Partial begins—4:09 AM EST, 1:09 AM PST;
Ends 7:49 AM EST (IF you can see it), 4:49 AM PST.
Totality begins—5:16 AM EST, 2:16 AM PST;
Ends 6:42 AM EST (IF you can see it), 3:42 AM PST.
What can you do with a total lunar eclipse? There are, of course, the obvious observational things to do.
Observe the coloration and shadow darkness, which measures atmospheric opacity.
Some telescopists time when the ‘sharp’ edge of the Earth’s shadow hits the center of lunar craters, a way to measure the enlargement of the shadow from pure geometric calculations.
There is the fun challenge of detecting and timing the first and last smudges of the penumbral shadings, and first and last umbral dark cuts on the Moon’s disk.
Simple photographic recording is fun, too. Unlike a total solar eclipse, you don’t need special equipment or have to travel to a narrow shadow path for a few minutes of eclipse glory. The eclipse is visible over a wide part of the world’s surface and it takes a leisurely pace of time to happen. And it isn’t entirely predictable what you will see.
Scientifically, the Moon has pretty much lost its usefulness but it still makes a good lab experience for students for a couple of experiments, which replicate some ancient ones. To wit, the measurement of the Moon’s distance and size.
Two Ways to Observe The Eclipse Educationally
Lunar Parallax Method
A direct way to measure the Moon’s distance required something forgotten by the Renaissance scholars, the size of Earth. But it also required something they completely lacked—the ability to get simultaneous measures of the Moon’s sky position during the eclipse from two far locations. Today we can do that easily! For this eclipse, an observer on the North American west coast or in the Pacific Basin and someone in, say, Japan, are in prime locations to take photos of the eclipsed moon as the exact same time and compare the stars around each photo. You would see the Moon is not in the same place compared to the stars. That’s parallax, the same thing surveyors use to measure landscape features from two places a known distance apart.
The complete Parallax method, which is recommended for this eclipse if you can find a partner far enough away AND you can get sufficiently dark skies and photographs of the stars near the totally eclipsed Moon, can be read at:
https://www.classroomastronomer.com/measurethemoon/lparallax.html .
Shadow Cone Method
The other way to get the Moon’s distance (and size) utilizes the fact that the shadow had to be a cone shape. HOW big a sphere and HOW FAR it was away was a geometry problem that required only two things: knowledge of how big was the Earth, and how long was the shadow?
Part 1—First, you have to find out how far the shadow of the Earth goes out in space; the math is more complicated than the triangles’ geometry of parallax. That occurs at a distance that is about 108 times the diameter of the Earth, give or take. Since Eratosthenes measured the Earth’s size pretty accurately thousands of years ago, and we know it better today, we can determine that the end of the Earth’s shadow cone goes out 108 X 7926 miles, or 856,008 miles. The cone’s size starts at 7926 and shrinks directly in proportion with the fraction of the way out you go, until it reaches zero size at 856,000 miles.
Part 2—With photographs or a drawing, every 30 minutes plot the shadow’s edge on the Moon’s surface. Remember to put the drawings in line properly knowing the Moon moves its own diameter in an hour. With passage THROUGH the Earth’s shadow (as opposed to a partial eclipse, as above) you should get a nice pair of curves, left and right side, defining the edge of the shadow of Earth. The circle that fits them should be about 2.6 times the size of the Moon’s disk (it varies a bit with each eclipse). Which means the shadow is ~1.3 degrees in size compared to the ~0.5-degree diameter Moon. But how far into the shadow, and how far from the Earth, is the Moon IN that shadow"?
Without deriving it here, the fraction f of the way out from Earth to the Moon in the shadow cone is f = 1/[((1.3/57.3)*108)+1), which is around 28%, on average, or around 240,000, though this varies from eclipse to eclipse from 238,000 to 252,000. You substitute your determined shadow size for 1.3, by the way.
Part 3—Given the distance, how big is the Moon? It’s all proportions! A) If the shadow is 28% (or whatever you determined) of the way out, that cross section is also then 28% less the size of Earth, or 7926*(1-0.28), or ~5700 miles. B) That visible shadow section was, say, 2.6 times the Moon’s size, so divide 5700 by 2.6, and you get 2192 miles for the Moon’s size, not too far from the known value of 2160! Use the numbers you find from your observations.
The complete Shadow method of determining the Moon’s size and distance can be read at https://www.classroomastronomer.com/measurethemoon/ShadowMethod.pdf .
- Stellar and Planetary Brightness Differences
The astronomers’ system of measuring brightness is logarithmic. Every magnitude is 2.512 times brighter or fainter than a star one number different. Every five magnitudes is exactly 100 times different in raw brightness. This can be hard to visualize, but we have a neat opportunity this first two weeks of November to see this.
On the evening of November 4 you can find Moon two degrees south of Jupiter. A Full Moon, which this Moon almost is, is magnitude -12.6, while Jupiter is -2.8, a difference of 9.8 magnitudes. Five magnitudes is 100 times, and five mags more is 100 times 100, or 10,000 times difference. A difference of 9.8 is 8300 times. That 0.8 difference doesn’t seem to make that much difference, but it does!
- Meteor Radiants Aren’t Stationary
There are two middling meteor showers during these two weeks, both radiating out of Taurus the Bull. The South Taurids come first, centered on November 5th, three days before Full Moon, so they truly will be best in the dawn hours when the waxing Gibbous Moon sets. It produces only about 10 meteors per hour from a point south and a slight bit west of the Pleiades star cluster. Six days later, on the 11th, the slightly stronger North Taurids peak, at 15 meteors per hour, but since the Full Moon just happened three days earlier, you aren’t going to get any dark skies to see many.
Both showers linger along for a week before and after their peak dates so one interesting challenge is to observe them, and plot their meteor streaks on the same star maps and see if you can distinguish the two showers at the same time. Also, their radiant points aren’t motionless so plotting the showers—and radiants DAILY—and watching them drift can be a fun observing project. The motions are a representation of the Earth’s moving through the meteor stream and the shifting of OUR viewpoint of the debris path, not anything having to do with the motions of the meteors themselves.
- What Kinds of Questions Can You Get from Making Craters from Meteors?
The Taurids are debris left over from earlier passages of a comet. We’re in no danger of any of these crashing down on us. But meteors do reach the Earth’s surface, and in the past larger ones have made craters on our planet’s surface, and other solid bodies in the Solar System—take a telescopic view along the day-night line on said crescent moon to see craters in high relief! But are all craters the same?
For young kids, just dropping a rock or ball into a container of dirt or mud and making a crater is a joy. But to be a more scientific lesson, you need to go into more depth of questioning and observation.
First, get a large aluminum pan and fill it with flour and put a layer of cocoa on top. Then drop marbles, small rocks, or other masses from various heights and see what you get as results.
Then, ask students to describe what they got (besides a mess—have lots of tarps or newspapers or other things to protect the floors if indoors). The kinds of observations (and/or questions you can ask) are as follows:
Zeroth level: It makes a hole.
First Level: Describe the hole size and spray and other observations you can make in and around the hole.
Second Level: Seek relationships between different variables, such as what happens as you change the height from which you drop the rock, use different rock masses from the same height, different shapes of rocks (round, elliptical ones, cubes, etc.), angles thrown at, and so on.
With older students, you might start this out by having students first actually look at the Moon (or more easily, Moon photos) and make a list of the types of Moon craters and features, before they start their experiments. You should get craters with or without central peaks, with or without rims, with ejecta spreads or rays or without, with terraced walls or not, and so on.
Then you can add one more question level—
Third Level: Can you find ways to reproduce the kinds of craters you see on the Moon? Craters with central peaks? Without them? With or without rim walls? Rays? What do you have to do, or change, to accomplish this?
So as you watch the Taurids, connect the shooting stars with the ancient relics of collisions on the Moon, and on the Earth, with scientific questioning and reasoning skills, in the classroom.
Astronomical Teachniques
When The Sun and Moon Look the Same Size, How Big Is a Shadow?
We have two solar eclipses coming up in the USA in the next two years, an annular (ring) eclipse and a total eclipse. The difference comes from the Moon’s distance from Earth being not the same each time; in an annular eclipse the Moon is near apogee, its farthest part of its elliptical orbit, and therefore appearing at a smaller apparent size such that it can’t quite cover the disk of the Sun. When closer, we get a total eclipse. Here are two things you can do to demonstrate this, one for younger kids, one for older ones.
1. NASA has put up a YouTube demonstrating how to show the effect of why a smaller but closer object (Moon, coin) can cover a bigger, similarly shaped object (Sun, round paper plate). The video is here:
2. Useful for both real solar and lunar eclipse studies, use a tennis ball and a white flat paper, cardboard or similar object (paper plate?) as a screen to project the ball’s shadow. Holding the plate near the ball, you immediately see that the shadow has two parts, the deeper umbra in the center and the grayer penumbra around it (as does your personal shadow—kids can be really surprised at that!). The objective is to find the distance where the umbra’s end is and the shadow is now all penumbra. You have to increase the distance with the help of a second person, or by positioning the ball high on a steady stand, and moving the screen until the umbra gets lost in the penumbra. Measure that distance and find the ratio of distance to ball diameter.
At the Earth’s distance from the Sun, the ratio SHOULD be around 108 (it varies slightly over the year), that is, the length of the umbral shadow cone should be 108 times the diameter of the ball. ANY ball. Tennis ball. Marble. Beach ball. Soccer ball. Moon. Earth. Why? Because for each sphere the Sun is exactly the same angular size, generating the same geometrical kind of cone shape. Same proportions, different dimensions.
Given that information, knowing that the Moon’s shadow JUST touches the Earth during a total solar eclipse, you can find the Moon’s size, if somehow you know that distance in miles or kilometers. Or vice versa. Knowing that the Moon is 400 times smaller than the Sun, you can find the Sun’s size that way (or the opposite), and ditto about its distance.
Note: It is best to do this near Sunrise or Sunset. You need a long horizontal distance to get that umbral shadow to disappear into the penumbra on your screen. A high Sun and a ball just a few feet of human height above ground won’t cut it.
CAPping off CAP: Reporter’s Notes
Not All Color Graphics Are Equal.
When you are making illustrations, not all things are seen equally, as was illustrated by UK’s Dr. Jayanne English in her CAP talk.
Take the red and blue shifts of light. Blue shifting is what happens to spectra when an object is approaching; red is when the object is moving away. It is not visually apparent except possibly at velocities approaching light speed. Nevertheless it is often illustrated in books with red and blue artwork. But to the human eye, common reds actually appear to approach the observer because of how red light interacts with the retina! (See the pair on the left in the picture below.) A different set of reds are needed (see the pair on the right)!
A Cosmic Partnership - A University-Library Cooperative for Caregivers and Children 4-7 Years Old
Many of the caregivers and parents come with negative emotions about STEM education; not necessarily so the children. Here is an interesting British idea between 4 libraries in some impoverished areas and the University of Hertfordshire to improve the expectations of families about STEM education.
The librarians are given books and kits and each session at the library includes story times for the children. The kits are for the children to work with at the library but there are books and kits that can be used at home.
The libraries got increased borrowing of STEM books and the families got increased engagement in STEM beyond normal measures.
Perceptions of Outreach - Results of a Survey
There was surprisingly(?) few educational sessions at the October AAS Division for Planetary Sciences meeting. The only significant one of note to me was on attitudes about outreach, a report of a survey by Sanlyn Buxner of the Planetary Science Institute (along with Chris Mead and Andrew Shaner).
Primary Results
More than 50% want to do more outreach.
Almost 50% say they are not satisfied with the types of outreach they are given to do.
Two-thirds have had no professional development on doing outreach.
Motivations, in descending order—
A sense of duty (give back to the community).
Increase public knowledge and excitement.
Ensure people are informed about science issues.
Get people to appreciate the role of science in daily life.
Correct misinformation.
Ensure culture values science, and people use science to make better decisions.
Encourage girls and minorities and children to pursue science.
Main Barriers (in descending order)—-
Time (76%) (By FAR the greatest barrier of all listed).
Others mentioned included lack of connections to communities visited, lack of knowledge of opportunities, lack of materials and activities to use, and lack of funds/incentives to do outreach.
What Incentives ARE available?
Main ones are, equally and mostly, Grant Support and Salary Support (57-58% each).
The four greatest things they want to learn are: Effective ways to engage under-served audiences, accessibility training for engagement, learning how to communicate with specific age groups, and learning and practicing activities to use in outreach. Despite the lack of financial support, surprisingly, the least item the surveyed wanted to learn was about fundraising and development for outreach.
Connections to the Sky
Pluto in Crisis
As an example of making astronomy concepts more human-relatable, a video group called India Science gave a lesson at CAP on scripting short videos making the concepts be more like characters. But how do you do that?
First, you have to have good dialogue. Write what (and how) people actually speak! We all know that SO MANY FILMS where characters do not talk like real people talk to each other.
It has to be relatable. Have friends, family, drama, conflict in your script.
Decide at the start— who is the target audience? Kids? Grandpa? (No, it is never going to be “Both,” or “All.”)
Challenge 1: Facts are Facts—Don’t get carried away, and don’t mold facts to the story, or for the sake of the story.
Challenge 2: Keep it reasonable and logical. There should be a need for a character. If no need, then don’t have the character.
Last, characters have emotions. Use them!
Example, Pluto in Crisis was all about Pluto’s demotion from planethood. How much more existential can you get? Below is the link to the 5.75-minutes-long YouTube video, with a sobbing childlike Pluto and fatherly Sun as the main characters. One glaring error—the probe that visited Pluto was NOT Space Horizons, but New Horizons. See it at https://www.youtube.com/watch? v=d3clUYWOnhw (delete the enclosed space).