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

Astronomy 210, fall semester 2014
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 really liked the first generation stars. It was a really pretty picture but it was also neat to learn that there was only hydrogen and the first massive stars started fusing it into heavier elements and that it was free of metals. So that was really cool and something I'll remember."

"I though the video of why the night sky is dark was very interesting, also how we can see parts of the night sky with no stars at all. A universe where no stars existed at the time."

"I was informed that the Big Bang was literally not a bang. I thought it was a bang the whole time and it started at a certain position. This is interesting to me because the power of reading helps clarify false assumptions."

"Lookback time."

"Olbers' paradox/question. I never thought about why the night sky was dark and not bright."

"It blows my mind that all of the elements in our bodies were created by hydrogen fusion in massive stars."

"Everything interested me in this section, this is the section I have been looking forward to the most. Finding out the beginnings of our galaxies and the beginning of our universe. Definitely interested in the theory of the big bang, makes a lot of sense when you think of the expanding aspect of the universe."

"The difference between metal-rich and poor stars"

"By the time the universe was a few minutes old all the protons and neutrons that are in our bodies had come into existence."

"OMG this week is SO AWESOME. The idea that when we look at the darkness of space what we're actually seeing is a time before stars blows my mind."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The space in between galaxies is expanding, but where does all this space come from?"

"The metallicities of the Milky Way and the difference between metal poor and metal rich. It was just confusing because there is so much information about it and I think I need someone to explain it to rather than just reading it."

"Olbers' paradox/question is still pretty confusing. It's confusing that the universe is limitless but finite. There isn't an edge?"

"I'm confused why we are talking about Facebook relationship statuses."

"I found it confusing that the universe is infinite but has a finite age."

"I don't understand cosmic expansion. How are all of the galaxies moving apart from each other? What is causing this?"

"If the universe is expanding are more and more stars being created at the edge of the universe? If so how is this possible?"

"How can just hydrogen change all the way into planets with self-sustaining ecosystems and create lifeforms?"

Indicate how the amount of these elements in the universe have changed over time.
(Only correct responses shown.)
Hydrogen: decreased [44%]
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.  ********* [9]
young stars that formed very recently.  ************************** [26]
(There is a tie.)  [0]
(Neither, as stars cannot have metals.)  [0]
(Unsure/guessing/lost/help!)  * [1]

Indicate what produced these elements.
(Only correct responses shown.)
Helium in the sun's core: the sun [22%]
Carbon in your body: another star, in the past [50%]
Calcium in your bones: another star, in the past [39%]
Iron in your blood: another star, in the past [44%]
Gold and silver from mines: another star, in the past [36%]

People breaking up a relationship are most likely to update their Facebook status to "single":
on Valentine's Day.  **** [4]
during spring break.  ***************** [17]
just after Thanksgiving.  ********* [9]
on Christmas Day.  ** [2]
(Unsure/guessing/lost/help!)  **** [4]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Wait, the animation you used for the expansion of the universe was zooming in--but if the distances between galaxies is increasing, shouldn't the galaxies be the things moving in the slides?" (If you lived in one of those galaxies, you would observe all other galaxies moving away from you.)

"You're most likely to see 'single' FB status updates a few days before the Mid-State Fair starts during the summer."

"Can you go over some more of where the elements were produced in class, please?" (Yes.)

"What I found confusing was the speed of light and how images we see actually differ from what is actually out there." (Light takes time to travel. Like if you just today received a postcard from your significant other breaking up with you--but then realizing your significant other actually broke up with you a few days ago.)

"What was before the big bang? If the universe started at a single point that keeps expanding, how did it start?" (One interpretation is that nothing existed before the big bang. Time (or more precisely, anything that could even keep track of time) was undefined, so "what existed before" may debatably not be answerable. And keep in mind that the universe did not start at a single point, the distances between everything everywhere in our infinite universe a long time ago were zero, and the distances between everything everywhere have been expanding ever since--at least this seems to be supportable by observational evidence.)

"If the idea of the blackness of the sky simply being a time before stars is true, though, wouldn't we have some kind of record of brand new stars/galaxies appearing and taking up a heretofore unoccupied space in the sky?" (Yes, that is what the closer galaxies (more recent lookback time) look like.)

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