20190424

Online reading assignment: the Milky Way (SLO campus)

Astronomy 210, spring semester 2019
Cuesta College, San Luis Obispo, CA

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on the Milky Way's shape, size and composition and spiral arm structure and formation.


Selected/edited responses are given below.

Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.
"I really liked learning about the Milky Way because when I was young and went to LA you couldn't see the Milky Way, but at home you could see it really nicely without the light pollution. Learning about dark matter was crazy as well because I didn't know a lot about it."

"I really liked learning about the Milky Way. I live out in the country so on super clear night growing up as a kid I was able to see the Milky Way."

"That the word 'galaxy' derives from the Greek word for milk, interesting fact."

"The fog model. The idea that there are things we can't see because of things being in the way is fascinating."

"How big the Milky Way is."

"I thought the bad hair day camping was a funny and interesting analogy."

"I guess I never really thought about how we would image our own galaxy, looking from the inside out. But the way that we do it is pretty interesting. It's confusing, but I'm sure the lecture will clear it up."

"That we actually have a method to determine our galaxy to be a spiral galaxy and it's not just assumption."

"I never thought about how hard it would be to figure out what size and shape our own galaxy is since we are inside of it and have no mirror for reference."

"Learning about the Milky Way and its spiral arms was pretty interesting. I liked it because the Milky Way is always talked about, but never in this much depth."

"That people were able to come up with ways to picture our own galaxy even though it's huge and we can barely get to other planets at this point."

"That we can use the orbital motion of the sun to find the mass of the galaxy inside the sun's orbit. The fact we're able to infer this correlation blows my mind. It makes total sense, too. Plus, even if it's not exact, the fact that we can even get an estimate also demonstrates just how interconnected everything really is. We've been able to learn so much about space already, even with the extremely limited data we actually have."

"Dark matter because the idea of unexplained and mysterious phenomena are always intriguing and exciting."

"I thought that the idea of dark matter was super-weird and interesting. But it does make a lot of sense."

"Dark matter is cool because is it scary and most of the universe is dark matter. Creepy."

"How we detected the spiral arm 'lanes' of the Milky Way, because they don't just use a regular telescope."

"The wildfire analogy for star births through type II supernova explosions was interesting. I find it helpful to have comparisons to more common everyday occurences that I have actual experience dealing with when trying to understand the abstract astronomy subjects."

"The formation of the Milky Way is based on a lot of theory, and that some of the mathematical estimations could be as much as 10% off. It's interesting to know that there is still much knowledge to discover."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Why can we see the Milky Way but we are a part of it."

"I'm still not totally sure about how we can use things like globular clusters to find the size and center of the galaxy, but after reading the textbook on the various ways we figured it out, that was cleared up more for me. I'm not really confused on anything else in this section."

"The globular cluster part about the Milky Way was a bit confusing. The image that was provided didn't make much sense to me--I just think I need a better, in class explanation."

"The period-luminosity relation."

"I want to know more about dark matter. What are your ideas of what it could possibly be made of?"

"Dark matter, I've always heard of the references to what darkmatter is and how its a major part of our universe, but the MACHOs and WIMPs categories still confuse me on the subject still."

"WIMPs--what is a weakly interacting massive particle? How can something be weakly interacting?"

"Star formation in spiral arms."

"How density waves work."

"The spiral arm/Pimpstar Rim optical illusion thing. I get it on a basic level, but I need more explanation."

"The spiral arms, I didn't really understand the concept of them."

"Self-sustaining star formation--why is it prominent in some galaxies and not all?"

"I think I'd just like more in class discussion on all the presentation slides."

"Just about everything I have read."

"Pretty straightforward slides!"

"It all clicked."

In your experience, how much of the "Milky Way" (the band of faint stars across the celestial sphere) have you been able to see in the night sky?
As much as can be seen with the naked eye.  ********* [9]
Not very much.  *************** [15]
Barely seen it.  *** [3]
(Never been able to see it.)  ***** [5]
(Unsure/guessing/lost/help!)  [0]

Using the most powerful light-gathering optical telescopes in the darkest skies, __________ of the stars in our entire galaxy can be observed from Earth.
1%.  ************ [12]
5%.  ***** [5]
10%.  ********* [9]
50%.  ** [2]
100%.  [0]
(Unsure/guessing/lost/help!)  **** [4]

If you did not have access to a mirror while camping, what could you do to find out whether or not you're having a bad hair day?
"Look in the reflection of a pond/river/lake."

"Check in the reflection of the water? Honestly, I'd have a hat though."

"If a car is nearby look in the window."

"Take a selfie."

"Ask your fellow campers or study their reactions to you when you climb out of your tent."

"Ask a friend you trust who has a verifiable history of qualifying good and bad hair days in accordance with your hair day system of values."

"Ask a wild animal."

"Ask a grizzly bear."

"I don't usually care about what I look like when I'm camping."

"Camping hair don't care."

"Probably just roll around in the dirt. Then I'll know for sure that I’m having a bad hair day, and there won't be any mystery anymore."

"Make sure your camping partners look worse than you so no one can tell you're ugly."

"Look at your shadow."

"I would use my hands to feel, if my hair is in place relative to my head."

"I would just run my fingers through it, the more knots the more painful the hair looks."

Look at PimpStar Rims (*.html) for cars, or MonkeyLectric Rims (*.html) for bikes. Briefly explain how they work.
"Rapidly blinking lights are coordinated to create patterns when swept across our field of vision."

"For Pimpstar Rims there is a microprocessor in each wheel and images are sent to each wheel through wirelessly. For MonkeyLectric, there are many different designs that are already picked out that were created by different artists."

"Using LED lights set into the rims of cars or bikes the lights are able to make a picture as the wheel spins. The article said they use 'strobe modulation effect' kind of like a marquee where the lights light up and make it appear as if the words are moving in fluid motion instead of lights just lighting up."

"Usually one 'spoke' made up of a handful of LEDs spin around fast enough to create what appears to be a solid disk. By changing the LEDs at a rate that correlates to the spinning speed, it can create a picture."

"I think the reason that they work is because the light on the wheels when going really fast make it seem that there's a solid color, similar to when you turn on the fan and the blades when going fast look like a single big blade. How they create the cool patterns I'm not sure."

"PimpStar Rims are rims on a car made to put a design/ make a visual illusion to people that drive by. The spiral arms of the Milky Way are a similar persistence of vision illusion--like the lights on Pimpstar rims, short-lived massive stars are born and die at certain intervals as they orbit around. MonkeyLectric Rims are the same but for bikes."

"The wheels have freaking pictures!"

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"If you could elaborate on the shape of our galaxy in class, please?"

"I'm a bit confused as to why the Milky Way galaxy is flat disk shaped. In the globular cluster positions slide, it shows the star clusters above and below the disk but there's still clusters inside the blue disk right? Where is the border where star clusters are officially part of the Milky Way and where they're not?" (Yes, the globular clusters are everywhere in the halo (above and below the disk), and also can pass through the disk as they circle around their tilted orbits.)

"Why is it called 'dark' matter when it is actually made up of light matter?" (We can't see dark matter (yet)--it doesn't give off light (like stars, or emission nebulae), doesn't reflect light (like fine dust), and it doesn't even block light (like clumpy dust particles). Perhaps a better term for dark matter is "non-light interacting matter.")

"Why did you want us to look at the ugly rims?"

"The LED lights for your bike are really cool and nicely personalized."

"I must be a child because I laughed at 'Pimpstar.'"

"Is it true that there are more stars in universe than grains of sand?" (If the universe is infinite, and each star in this infinite universe has a planet with sandy beaches, then probably so. #mindblown)

"How do you feel about 'Song About The Sun' by They Might Be Giants?" (Eh. It's okay.)

"We should do a potluck!" (We'll do a "knowledge potluck" for the final exam. Just make sure you at least bring enough for yourself.)

"Do you like camping? Do you consider yourself to be high-maintenance?" (Yes, and probably yes. I usually just wear a hat when backpacking, though. #doitforthegram)

"What was your Ph.D. research on? Why'd you choose that?" (Atomic holography. Because, holograms. Of atoms.)

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