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

Astronomy 210, spring 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.
"How our bodies' composition came directly from star deaths. The formation of who we are intrigues me."

"That when we look at Deneb, we are seeing it how it was 1,400 years ago."

"The big bang because it's crazy to me how people still don't believe it to be true"

"The big bang theory, because I like the TV show The Big Bang Theory, it's funny."

"I thought that the look-back time part was really interesting. The fact that we are viewing stars as they were years and years ago is another part of astronomy that blows my mind!"

"I liked learning about the big bang theory because its something you hear about as far back as elementary school so it was interesting to hear actual scientific explanations about it."

"That the Milky Way galaxy became what it is today by accumulating other galaxies and how our galaxy has so many different types of stars."

"To learn that the universe is getting dirtier and dirtier as more hydrogen is being formed into metals, and that we are made up of the dirt resulting from the formation of the planet, because I'd never thought of it this way before."

"That we are able to tell distinguish between older and younger stars by looking at absorption lines from atoms in their outer layers. This is interesting to me because the elements in the outer layers of stars are giving us insight to their age."

"That older stars are metal-poor while newer stars are metal-rich. I would think it would have been the other way around."

"The 'edge of the universe' is incredibly interesting to me. The fact that it isn't the non-objects that we're seeing but non-time makes so much sense that it just generates question after question."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"how looking at distance stars represents how they looked back in the day, not how they are now."

"I found light speed look back times to be the most confusing because I don't understand how we can somewhat look into the past."

"That stars were around for so long before us, where did we REALLY come from?"

"Why people find The Big Bang Theory TV show funny."

"Metal-rich versus metal-poor was super confusing, and it's confusing because I don't understand."

"The Hubble law was confusing to me. The nature of the expansion was unclear."

"The difference in metals between younger and older stars."

"What was there before the universe? How are scientists able to talk about what happened before the universe when it wasn't even born yet?"

"Metallicity. Not exactly sure what that is."

"I didn't really get the whole 'we are made of stars' things."

"Not sure about the edge of the universe. How do we know it isn't infinite? Is it possible we have not developed technology good enough to see 'farther into the forest?'"

"I thought all the elements came from Earth."

Indicate how the amount of these elements in the universe have changed over time.
(Only correct responses shown.)
Hydrogen: decreased [78%]
Metals (elements heavier than hydrogen and helium): increased [81%]

The outermost layers of __________ are more abundant in metals (elements heavier than hydrogen and helium).
extremely old stars that formed a long time ago.  ****** [6]
young stars that formed very recently.  **************************** [28]
(There is a tie.)  [0]
(Neither, as stars cannot have metals.)  * [1]
(Unsure/guessing/lost/help!)  ** [2]

Indicate what produced these elements.
(Only correct responses shown.)
Helium in the sun's core: the sun [65%]
Carbon in your body: another star, in the past [57%]
Calcium in your bones: another star, in the past [57%]
Iron in your blood: another star, in the past [57%]
Gold and silver from mines: another star, in the past [57%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Please don't make the final too hard." (Sure, just "hard enough" will do.)

"How big of a bang was the big bang?" (Well, it wasn't a "bang" so much as a gradual expansion of the space between galaxies, but it is/was "big," as the expansion is everywhere in this infinite universe.)

"Do you believe in the big bang theory?" (Well, I understand that it is the most consistently explanation for the factual observations we see out in the universe around us--that the night sky is dark, and that galaxies are all receding away from each other.)

"If we kept going in space through the dark would it eventually become bright or will it always be dark no matter how far you see/go?" (It would be dark, with no stars, as you would be looking out into the past, before there were any stars. However, looking further out, you would be looking so far back out into the past that you would see the faint energy remnants of the early big bang. But you can't look out further than that.)

"Is the starting point of the universe, where the big bang occurred, in the center?" (Since the universe started with zero space between everything, everything was "in the center," but this is a somewhat misleading concept, as there is no unique "center" in an infinite, expanding universe.)

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