20131201

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

Astronomy 210, fall semester 2013
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.

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 think it's so interesting that the universe has a finite age, but the universe is not infinitely old. I really can not imagine how the universe would have started."

"The monolithic collapse model of the Milky Way. I liked the visual in the online presentation. I find concepts like these more understandable when there is an animation."

"The idea of the big bang is cool. Seriously I thought that entire presentation was beyond interesting. Especially thinking that we can see to the edge of time. That's craziness."

"Halo stars orbit the Milky Way tilted at different angles, while disk population stars move around the Milky Way in co-planar orbits."

"I did not know that when supernovae explode that they pollute the universe's unused hydrogen with metals."

"There are theories about whether or not the universe is infinite. I've always thought that the universe had no end, and I guess there's no way we'll ever no for sure, but it's interesting to speculate about these things."

"Entire small galaxies were captured by growing Milky Way and fresh gas was added to the disk. I have never thought about that! I live out in the country, so it is so completely dark and I love to just look up the stars and see soooo many stars in the sky and I love looking at the Milky Way. I always question myself about Milky Way, but could never answer those questions myself. And telescopes as time machines is really interesting!"

"That a scientist can tell if a star is older or newer depending on if it is metal-rich or metal-poor."

"It was interesting to learn that the universe does not have a center or an edge. I had never considered if the universe had a center or an edge before."

"I thought that the video about why the night sky is dark was really interesting."

"The concept of look-back time is awesome. You're looking back in time when viewing a distant object, that's awesome!"

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Metallicity. I found the difference between metal-rich and metal-poor stars confusing."

"I don't get how the Milky Way could have once been spherical in its distribution of hydrogen and it just sort of flattened."

"The different types of stars and their explosions and remnants."

"Trying to visualize how the big bang happened, it's difficult to try and understand something we can't fully explain."

"How exactly the Milky Way 'swallows up' nearby dwarf galaxies."

"Well a lot of this stuff about the big bang went right over my head. I am hoping you will be able to clear most of it up in class."

"I didn't find anything to be too confusing."

"There was nothing confusing--it was just quite a bit of information to remember."

"I didn't really understand what the Hubble law is trying to say."

Indicate how the amount of these elements in the universe have changed over time.
(Only correct responses shown.)
Hydrogen: decreased [54%]
Metals (elements heavier than hydrogen and helium): increased [67%]

The outermost layers of __________ are more abundant in metals (elements heavier than hydrogen and helium).
extremely old stars that formed a long time ago.  ************** [14]
young stars that formed very recently.  ******************* [19]
(There is a tie.)  *** [3]
(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 [28%]
Carbon in your body: another star, in the past [28%]
Calcium in your bones: another star, in the past [23%]
Iron in your blood: another star, in the past [26%]
Gold and silver from mines: another star, in the past [28%]

People breaking up a relationship are most likely to update their Facebook status to "single":
on Valentine's Day.  ****** [6]
during spring break.  ******************* [19]
just after Thanksgiving.  ********** [10]
on Christmas Day.  * [1]
(Unsure/guessing/lost/help!)  *** [3]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How do we know if we need to take the final?" (Your course points will be posted just before finals week--if you are content with your pre-final grade, then you do not need to take the final. If you think you can reasonably get enough points on the final to make the next letter grade jump, then you should take the final. If the points required to make the next letter grade jump are beyond what you could reasonably get on the final, then you have a choice to not take the final.)

"For the above question, I think the hydrogen in the universe decreased over time...why is that? P.S. I'm so ready for Christmas and Christmas break!!!!" (Stars fusing hydrogen into metals--there's no going back from metals to hydrogen. P.S. Me, too.)

"Did all elements on the periodic table come from stars exploding? Or are some formed here on Earth from the building blocks of what exploded?" (All elements (atoms) heavier than hydrogen were made from stars fusing hydrogen, then exploding. Molecules, which are atoms put together, were then made afterwards from these atoms, especially here on Earth.)

"Do you believe a creator made all this, or did all this happen just by chance?" (Yes, because religion; and maybe, because science.)

No comments: