Astronomy For Educators

Very few observing days in March, typically the wettest month of the year here.

Astronomy 101 - Why Teach the Geocentric System?

In teaching astronomy, I've often been asked: "Why teach the ancient Geocentric (Earth Centered) solar system if you know it isn't true? There are two main ideas at work here.
1) You cannot possibly understand modern astronomy thoroughly without understanding where modern ideas come from. The history of scientific thought is worthy of study.
2) Ancient ideas are often dismissed as stupid by modern educators - nothing could be further from the truth!

In the second or third week of class, I sometimes dressed up in a white wig and wrapped a white sheet around my body as a toga, and introduced myself. "Hello, my name is Aristotle, I'm your substitute teacher for today!" I would then teach the Earth-centered solar system as literal fact. It usually didn't take too long for someone to challenge me and say: "That isn't true! The Sun is in the center!"

My challenge to the students: "Prove me wrong!" Never once in over 40 years of teaching astronomy was a single student able to refute the geocentric idea. My "Aristotelean" arguments were persuasive - even though they were incorrect. My point? Ancient theories were not stupid, they were complex and subtle. Refuting them required careful thought and clever experimentation!

In fact, The Sun-centered and Earth-centered theories of the solar system persisted side-by-side for over 2,000 years. Why? No one had the equipment or knowledge to perform a critical experiment that would refute one theory or the other convincingly.
Teaching the HISTORY of science also teaches the PROCESS of scientific thought, and how science functions as a self-correcting process.

How do we teach Astronomy?

To teach astronomy, the educator must understand that we are building an entirely new worldview within the student's mind. There can be no true understanding of the cosmos if we remain rooted in our simple, earthbound perspectives.

Understanding the Moon is a prime example. How do phases work? We've all seen the Moon change, waxing from a thin crescent to full moon, and then the odd sensation during the waning phases when the Moon is visible in daylight. Generally, we do NOT think about it because we have no context or perspective that will allow us to understand.

This is why I use both diagrams and simple models models in preference to complex mathematics or long lists of vocabulary words to memorize. Placing a model, simple ping-pong balls painted or colored, glued to a coin or a bottle cap. The student can move the Moon around the Earth in orbit, examine the models on a tabletop - nothing happens, no phases appear.

Now place your eye near your model Earth and "look outward" toward the Moon - Aha! Phases magically appear! It is not that the Moon shows phases to anyone, no matter where you are in space. In fact, the only perspective that allows you to see the Lunar Phases is looking outward toward the Moon from the surface of the Earth, at center of the Moon's orbit will allow you to see the phases.
Looking at a model on a table top, from a perspective that would be millions of miles out in space, you see no phases at all. A simple painted ping-pong ball can change how we view the world forever.

You can find a detailed guide to this activity in my free book: Astronomy For Educators. The free download is available through my university here:
scholarworks.uark.edu/oer/2

Had a lovely visit with an old friend who took my Astronomy 101 class almost 20 years ago. I dug out my lecture notebooks from that era. As my friend & I reviewed these, she encouraged me to post these when she said: "Doc, I can hear your voice when I read these!"

I have decided to post these lecture notes for a variety of reasons, but primarily in the hope that they will inspire thought & discussion and perhaps inspire other educators to do as I have done - not just teach, but take your students out beneath the night sky and observe the heavens!

Please keep in mind that these are *outlines*. Each set of notes provided materials for apox. 3 hours of classroom time. To my knowledge, no recordings of the lectures exists. If any of my old students have such recordings, or have thoughts about those classes, I would love to hear from you.

If you are currently teaching astronomy and would like to use the materials, you are free to do so as long as you attribute my authorship. If you have questions or comments, please post them!

-- Dr. Daniel Barth

Star Mentor has climbed in the rankings on Amazon, now #355 in all Astronomy & Astrophysics books and also in the top 500 in Science for Kids. Hitting BOTH lists with one title is a real accomplishment!

Thanks so much to everyone who has purchased the book! I appreciate your support more than I can say!

The mount for the big refractor has been set up!
No counterweights & no scope mounted yet - still have to build the scope dolly! This is a Celestron CGE Pro mount, circa 2005. It has been a couple years since I last set this up - mostly because I need a partner (or two!) to help assemble it these days - the dolly should eliminate that hassle so I can use it on my own again!Can't wait to mount & balance the scope so I can see how its tracking after all this time!

For reference, that roll-up door is 7 ft tall (2.14 m). The rig as it sits (no counterweights) is about 170 lbs (77 kg). The counterweights will add another 55 lbs (25 kg), the scope adds 45 lbs with diagonal & eyepiece, guidescope, etc. The total rig comes to 270 lbs (123 kg!)

Ready for Hallowe'en night! Saturn, Jupiter, & Venus are tonight's treats!

This shows the location of the Chaffee fire in western AR. Blue circle is our location, blue arrow shows direction fire is moving, wind has shifted from southerly to S'westerly this morning. Major smoke plume in brown. We are about 12 miles away from flames and safe for now. Air quality is very poor this morning.

We'll keep all y'all updated.

Best selfie ever.

Lasers are so interesting!
Firing a laser at a paine of glass at a shallow angle causes the beam to split and the lightwaves interfere with each other. Make this a double paine of insulated glass and the patterns become delightfully complex!

One of these photos shows the reflections in the glass. The other shows the patterns projected onto a wall a few meters away. Notice that each pattern is an exact copy, each diminished in size and brightness! The beam also illustrates concentric polarization and interference. The fact that the patterns are not concentric shows that the window glass in my home is not perfectly flat! These interference patterns can be used to test telescope mirrors and lenses revealing the perfection of the optics to a fraction of a wavelength of light - literally a few billionths of a meter!

Lovely observing weather last night! I had the big 127mm binoculars out to observe Saturn.

Many people think you must have 150-300x to observe planets properly - this isn't true! I begin observing Saturn with an Explore Scientific 24mm, 62 degree eyepiece which gives me just 27x. This is perfect for capturing Saturn and its surroundings. The inner moons are found within 2-3 ring diameters, but Titan & Iapetus can be up to 15 ring diameters away - if you are zooming in, you will never see them! I use the chart in the photos to document what I see at the eyepiece. There was another object in the ring plane about 15 diameters east of Saturn, but a later check determined this to be a star and not a moon.

After checking the surrounding starfield, I switched to an 11mm, 82 deg eyepiece to look for inner moons. Rhea was distinct at 59x, Dione was at the limit of visibility, winking in and out, but its consistent position was enough to convince me to record its position.

The next morning, I used Stellarium software to check my observations & identify the moons. I always record first and check later - it helps limit confirmation bias in my observations. I'll be out again tonight - the inner moons will have changed position substantially. I'll also be using a tracking mount and higher magnification to take advantage on Saturn's edge-on rings!