Online reading assignment: Milky Way history, big bang clues (SLO campus)

Astronomy 210, spring semester 2017
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 history of the Milky Way and big bang clues, a comic strip adaptation of of Neil deGrasse Tyson's "The Most Astounding Fact" 2008 interview for TIME magazine, and Minute Physics' video explanation of Olbers' paradox.

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 had no idea we were in the Milky Way."

"how we are really just made up of the guts of a star explosion."

"The history of the Milky Way was interesting because I learned that the universe is progressively becoming filled with more metal-rich stars. If stars born are filled with materials heavier and heavier than hydrogen, the landscape is going to look way different."

"The idea of all elements being formed by the starts of the universe."

"I am a big fan of Rudyard Kipling. I enjoyed how you referenced one of his works to help us understand that the big bang theory doesn't just come from hearsay but well-known facts."

"The further out in space we look, the further back in time we look. The connection of those two is really cool."

"Be able to look back in time. That blows my mind. I try to imagine seeing something through a telescope at a certain age but if I go and see it in person it could be millions of years gone and dead. What?!?"

"When you look at a star that's 5,000 light years away, you're looking at it not how it appears now, but 5,000 years ago...CRAZY!"

"The fact that space is infinite in an eternal universe was beautifully intriguing and that what it infinite is the age of the universe. Also that the space between galaxies continues to grow."

"The big bang, mostly because of how much it is spoken of, and how little I know about it."

"Olber's question: why is the night sky dark? I just never questioned it, and now I can say it is because the universe had a beginning and our telescope 'time machines' only go back 13.7 billion years and the more distant stars' light hasn't reached our observable galaxy yet."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The change in elements amount over time."

"I don't understand where metals come from."

"I kind of found the whole look-back time with the stars confusing."

"The concept of telescopes as time machines is confusing. I know that when we look in the telescope it is actually showing us parts of the universe and what they looked like in the past. In reality, it makes sense since most of the objects in space are separated in light years but the concept is so bizarre that my brain doesn't want to understand it because it seems impossible."

"I'm confused about the edge of space idea, is there an edge or not? I understand the bit about looking through time but I don't get how it connects to the edge part."

"The universe expanding is confusing because it is so hard to visualize."

"The expansion of the universe. I guess I see why that conclusion is gathered, (red shifting galaxies in all directions means space is being made between us and them?) but what are we growing into?"

"How do we know that the universe is infinite in terms of space? The video seemed to imply that time was finite, while space was not."

"The Hubble law in general was very confusing, I simply just don't understand it by only reading. If you could explain this is class that would be great."

"How the Hubble law actually works. How do we know that the galaxy is (or isn't) expanding from some center? Or if only parts are of the universe are moving and not all?"

"The concept of the big bang is interesting because what we are taught or think isn't really the case and I didn't know that until now. Its always just assumed that it was a big explosion in a specific point in space or something, but in reality it happened everywhere and it was only our galaxy expanding from being small and compact."

Indicate how the amount of these elements in the universe have changed over time.
(Only correct responses shown.)
Hydrogen: decreased [60%]
Metals (elements heavier than hydrogen and helium): increased [77%]

The outermost layers of __________ are more abundant in metals (elements heavier than hydrogen and helium).
extremely old stars that formed a long time ago.  ********* [9]
young stars that formed very recently.  **************** [16]
(There is a tie.)  [0]
(Neither, as stars cannot have metals.)  * [1]
(Unsure/guessing/lost/help!)  **** [4]

Indicate what produced these elements.
(Only correct responses shown.)
Hydrogen in the sun's core: the very early universe [54%]
Helium in the sun's core: the sun [27%]
Carbon in your body: another star, in the past [47%]
Calcium in your bones: another star, in the past [43%]
Iron in your blood: another star, in the past [47%]
Gold and silver from mines: another star, in the past [37%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How weird/creepy would it feel to only see in infrared constantly?" ("Heat vision" cameras detect the far-infrared light given off by warm and hot objects (like in the movie Predator). "Infrared photography" uses film that is sensitive to reflected near-infrared light from the sun, just between visible light and "heat" light; plant leaves look bright because they reflect near-infrared light (so everything looks like a snowscape), and people's eyes look dark because near-infrared light does not reflect well off of their irises.)

"If you had the chance to see the edge of time but you had to go alone, would you do it?" (Mrs. P-dog and I have both verified that the night sky is dark (and not infinitely bright), and remember that this is evidence that the universe does not extend forever, but has an "edge in time.")

"The 'Why is it Dark at Night?' video I found soooo confusing, please explain."

"Is it possible that the universe is really filled with stars, but we just can't see that because we are limited by how long ago we saw the light emitted from different galaxies?" (Yes!)

"Thinking about the edge of the universe and how it could just end makes my anxiety spike."

"A little more explanation on the big bang would be greatly appreciated."

"Do you believe in the big bang?" (I don't think you should or shouldn't "believe" what evidence tells you, but I understand the observations that are consistent with the expansion of space between galaxies starting from an early high-temperature, high-density state. And it would be fair to say that you'll be tested on understanding that evidence as well.)

"Could there be possibly be no edge to the universe kind of like how Earth is round? It appears 'flat' to an still observer and common sense tells you that you can't see more so there must be an edge, but if you keep going in one direction for long enough, you end up in the same place you started. What if the universe is like that, but no matter which direction you go, you can end up in the same place (just a whole lot bigger and more dimensional than Earth)?" (That is one model of how spacetime might be curved "around itself," but the most current measurements of the overall curvature of spacetime in the universe indicate that it is very nearly flat (in a three-dimensional sense), and this would be consistent with it extending forever.)

"I hate The Big Bang Theory TV show." (Yeah, I'm not a fan, either.)

"How scientifically accurate is the science in the TV show Big Bang Theory?" (Apparently the show-runners have a science advisor, but that doesn't necessarily translate to making the characters accurate representations of normal, real-life scientists (which is what I have problems with).)

"It's really hot outside. So hot that I had to make a comment about it."

"Space is dirty. So my room can be dirty too. Take that, Mom!"

"What do you like to do during summer break?" (Hiking and camping with Mrs. P-dog.)

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