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

Astronomy 210, fall semester 2016
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 found the process used to move the narrative of the big bang as purely conceptual to one that was based on observable evidence was really a well-thought out method. I specifically like the point about the long time exposure taken by the Hubble Space Telescope and how that was related to a concept about being lost in a werewolf ridden forest. It seems almost too simple that looking in one direction for 'gaps' would actually yield results but it is actually an extremely logical solution to questions regarding the edge of the universe."

"When it mentions that even though we can tell the universe has edges, the further out you look the further in the past you see things. I had prior knowledge of both of those concepts individualy but I never put together that when we look at the farthest point out in space it's actually the furthest in the past and since the universe is expanding the edges are actually further out than we see them. That's so cool."

"That the universe is constantly expanding in all different directions."

"That the universe was basically started with hydrogen. That is personally interesting to be because it came so complex from only one element."

"I found the explanation of what 'metals' are in astronomy helpful. I always imagined it was like regular metals we have on Earth and didn't realize it referred to atoms heavier than helium."

"From the textbook: 'When you look at a galaxy millions of light-years away, you do not see it as it is now but as it was millions of light years ago when it's light began the journey towards earth.' I thought this was so fascinating because we all look at things as they are, but we never knew that we were looking at something the way it was."

"Being able to see the past with telescopes was very interesting because everything that we have seen is only the past making the universe even more a mystery."

"The new stars have the most metals, I feel that the older stars would have more time to develop more metals."

"I found it weird that when you look at space you're essentially looking into the past."

"We are star stuff! I've always said this and believed this and I am so stoked to finally delve into it!"

"Crazy to realize that the elements that make us and the world around us are made of dead stars."

"I've always found it so interesting how we're all made out of star dust. I remember learning that in high school astronomy and I think about it all the time, super cool."

"I really enjoyed learning that we are made up of star dust because it adds a new meaning to looking at the stars."

"That the universe is progressively getting dirtier is interesting because it makes sense and from what we have learned so far I understand why and how it is happening."

"Learning about how our Milky Way was created was very interesting. It was personally interesting for me because I never new how it started. Starting out from just hydrogen then learning about how the first generation stars (type II supernova) were just exploding was interesting."

"The universe is expanding...............!!!"

"What I found interesting is how we are an expanding universe."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Will there ever be an end to the expanding universe? What are some theories about the end?"

"Metallification is still confusing to me, why does it help determine a star's age?"

"From the textbook: 'There is no center to the expansion of the universe, so you would not see galaxies approaching a single spot. Rather, you would see the space between galaxies disappearing, distances between all galaxies decreasing without the galaxies themselves moving, and eventually galaxies beginning to merge.' I don't know the importance of this, but whether important or not, I am still like WHAAAAT?!?!?"

"Nothing was too confusing with the reading assignments."

"That there is an edge of the universe. I understand that there has to be but my brain cannot process it."

"Seeing through telescopes are like travelling back in time?"

"The edge of the universe and the gaps. How do we know it has an edge? What is there are galaxies further than Hubble can see? This confuses me."

"Why are galaxies redshifting from us?"

Indicate how the amount of these elements in the universe have changed over time.
(Only correct responses shown.)
Hydrogen: decreased [80%]
Metals (elements heavier than hydrogen and helium): increased [84%]

The outermost layers of __________ are more abundant in metals (elements heavier than hydrogen and helium).
extremely old stars that formed a long time ago.  * [1]
young stars that formed very recently.  ********************** [22]
(There is a tie.)  [0]
(Neither, as stars cannot have metals.)  [1]
(Unsure/guessing/lost/help!)  * [1]

Indicate what produced these elements.
(Only correct responses shown.)
Helium in the sun's core: the sun [40%]
Carbon in your body: another star, in the past [76%]
Calcium in your bones: another star, in the past [64%]
Iron in your blood: another star, in the past [68%]
Gold and silver from mines: another star, in the past [60%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"What will our final exam look like? What time is it?" (The Final Exam will be Wednesday, December 14, 7:00-9:00 PM here (this classroom). The study guide for the final is now posted on the website on the last day of class announcements page.)

"When are we going to start prepping for the final? (:" (That's up to you; the topics covered on the Final Exam have already been posted.)

"Since a massive star collapses after a certain point due to the elements past iron removing energy rather than creating it, so does that mean that it may be possible to create even more elements?" (Yes, that's how we get everything else on the periodic table of elements heavier than iron.)

"How can we see Deneb as it was 1,400 years ago? That just blows my mind." (The light you see from Deneb tonight took 1,400 years to get to you, so it had to have started out from Deneb 1,400 years ago. Similar to how a postcard you receive from Europe today took on week to get to you, so it had to have started out from Europe one week ago.)

"If someone reached the edge of the universe and then kept going, would they become the new edge of the universe?" (From what we know so far, there is no physical edge in space (just an "edge" in time, but that's just from our perspective looking outwards in all directions). So you could physically move around anywhere in space, you wouldn't encounter a physical edge, but just keep moving on further and further away.)

"I don't understand what you want us to know about the big bang theory." (I don't expect you to "understand" the big bang theory (I don't anyone really does), but I would like you to describe the evidence that indicates that we live in a universe that has distances between galaxies that have been continuously expanding for approximately 14 billion years.)

"How do you think the big bang happened? where do you think we--the universe--all came from?" (There aren't any answers to this questions...yet. But there are a lot of theories right now, but not enough evidence to prove or disprove any of them.)

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