20170323

Astronomy quiz question: meeting only the second IAU planetary qualification

Astronomy 210 Quiz 4, spring semester 2017
Cuesta College, San Luis Obispo, CA

Refer below to the minimal qualifications established by the International Astronomical Union for a planet:
I. Orbits the sun.
II. Shape "rounded-out" by gravity.
III. Cleared/dominates orbit around sun.
Which solar system object(s) only meets qualification II, but does not meet qualifications I and III?
(A) Mercury.
(B) The moon.
(C) Phaethon, a small asteroid.
(D) Makemake, a dwarf planet.
(E) (More than one of the above choices.)
(F) (All of the above choices.)
(G) (None of the above choices.)

Correct answer (highlight to unhide): (B)

Mercury orbits the sun (meets I); is "rounded out" in shape (meets II); and does not share its orbit around the sun (meets III).

The moon orbits Earth (and does not directly orbit the sun, failing qualification I); is "rounded out" in shape (meeting qualification II); and does not dominate its orbit around the sun (failing qualification III), as it is gravitationally bound to orbiting Earth as Earth orbits the sun.

Phaethon orbits the sun (meets I); its shape is not "rounded out" (fails II); and does not dominate its orbit around the sun, sharing it with other asteroids (fails III).

Makemake orbits the sun (meets I); is "rounded out" in shape (meets II); but does not dominate its orbit around the sun, sharing it with other Kuiper Belt objects (fails III).

Thus the moon is the only object listed here that only meets qualification II, but does not meet qualifications I and III.

Section 30674
Exam code: quiz04nqyL
(A) : 0 students
(B) : 16 students
(C) : 3 students
(D) : 1 student
(E) : 0 students
(F) : 0 students
(G) : 3 students

Success level: 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

Section 30676
Exam code: quiz04sl4M
(A) : 0 students
(B) : 17 students
(C) : 9 student
(D) : 4 students
(E) : 7 student
(F) : 0 students
(G) : 2 students

Success level: 49% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.74

Astronomy quiz question: IAU classification of spherically-shaped(?) Chariklo

Astronomy 210 Quiz 4, spring semester 2017
Cuesta College, San Luis Obispo, CA

Refer below to the minimal qualifications established by the International Astronomical Union for a planet:
I. Orbits the sun.
II. Shape "rounded-out" by gravity.
III. Cleared/dominates orbit around sun.
Chariklo is an object that has an unstable orbit around the sun, directly influenced by Uranus' gravity. Chariklo is surrounded by two rings (nicknamed "Oiapoque" and "Chuí"), and probably has at least one small moon still waiting to be discovered. The exact shape of Chariklo is not yet completely known. According to the IAU qualifications, if Chariklo is found to have a rounded shape, it would be classified as:
(A) a moon.
(B) solar system debris.
(C) a dwarf planet.
(D) a planet.
(E) (None of the above choices.)

[*] eso.org/public/news/eso1410/.

Correct answer (highlight to unhide): (C)

Chariklo directly orbits the sun (meeting qualification I), and with a spherical shape, it would also satisfy qualification II. However, it does not satisfy qualification III (as it is directly influenced by Uranus' gravity), which would then classify Chariklo as a dwarf planet. (If Chariklo had an irregular shape, then it would only meet qualification I, while not meeting qualifications II and III, which would then classify it as solar system debris.)

Section 30674
Exam code: quiz04nqyL
(A) : 2 student
(B) : 2 students
(C) : 15 students
(D) : 2 students
(E) : 1 student

Success level: 66% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.83

Section 30676
Exam code: quiz04sl4M
(A) : 6 students
(B) : 2 student
(C) : 26 students
(D) : 5 students
(E) : 0 students

Success level: 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.39

Astronomy quiz question: IAU classification of irregularly-shaped(?) Chariklo

Astronomy 210 Quiz 4, spring semester 2017
Cuesta College, San Luis Obispo, CA

Refer below to the minimal qualifications established by the International Astronomical Union for a planet:
I. Orbits the sun.
II. Shape "rounded-out" by gravity.
III. Cleared/dominates orbit around sun.
Chariklo is an object that has an unstable orbit around the sun, directly influenced by Uranus' gravity. Chariklo is surrounded by two rings (nicknamed "Oiapoque" and "Chuí"), and probably has at least one small moon still waiting to be discovered. The exact shape of Chariklo is not yet completely known. According to the IAU qualifications, if Chariklo is found to have an irregular shape, it would be classified as:
(A) a moon.
(B) solar system debris.
(C) a dwarf planet.
(D) a planet.
(E) (None of the above choices.)

[*] eso.org/public/news/eso1410/.

Correct answer (highlight to unhide): (B)

Chariklo directly orbits the sun (meeting qualification I), but with an irregular shape, it would not satisfy qualification II, classifying it as solar system debris. It also does not satisfy qualification III (as it is directly influenced by Uranus' gravity), but this does not affect its solar system debris classification. (If Chariklo had a spherical shape, then it would meet both qualifications I and II, while not meeting qualification III, which would then classify it as a dwarf planet.)

Section 30674
Exam code: quiz04nqyL
(A) : 1 student
(B) : 21 students
(C) : 0 students
(D) : 0 students
(E) : 1 student

Success level: 92% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.17

Section 30676
Exam code: quiz04sl4M
(A) : 1 student
(B) : 35 students
(C) : 1 student
(D) : 0 students
(E) : 2 students
(No response: x students)

Success level: 91% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.25

Astronomy quiz archive: solar system

Astronomy 210 Quiz 4, spring semester 2017
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz04nqyL


Section 30674
0- 8.0 :  
8.5-16.0 :   ****** [low = 12.0]
16.5-24.0 :   ****** [mean = 23.6 +/- 7.7]
24.5-32.0 :   *******
32.5-40.0 :   **** [high = 36.5]

Section 30676, version 1
Exam code: quiz04sl4M


Section 30676
0- 8.0 :   * [low = 7.0]
8.5-16.0 :   ********
16.5-24.0 :   ************** [mean = 22.9 +/- 7.8]
24.5-32.0 :   *********
32.5-40.0 :   ******* [high = 36.5]

20170322

Online reading assignment question: keep, quit, start

Astronomy 210, spring semester 2017
Cuesta College, San Luis Obispo, CA

"2017-03-Astr210-keep"
Waifer X
flic.kr/p/RWBywk

Wordle.net tag cloud for "keep" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2017.


"2017-03-Astr210-quit"
Waifer X
flic.kr/p/RWBysT

Wordle.net tag cloud for "quit" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2017.


"2017-03-Astr210-start"
Waifer X
flic.kr/p/SWGWth

Wordle.net tag cloud for "start" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2017.

Students were asked to answer a "keep-quit-start" online reflection (hosted by SurveyMonkey.com) on their studying strategies/pitfalls (Mubayiwa, 2009).
Enter a word or brief phrase that describes what you intend to keep doing to study for this class. Explain your answer to the above question (what you intend to keep doing to study for this class).

Enter a word or brief phrase that describes what you intend to
quit doing to study for this class. Explain your answer to the above question (what you intend to quit doing to study for this class).

Enter a word or brief phrase that describes what you intend to
start doing to study for this class. Explain your answer to the above question (what you intend to start doing to study for this class).
[Word tags have been edited to consolidate related common subjects; student explanations are verbatim.]

Keep word tags:
caring
     I find my self the most motivated to put forth effort in this class when I am intrigued. When I think of each of the school subjects and each of my obligations and gauge it by its inherent wonder and overall significance, I find astronomy to be high on the list. This sense of intrigue motivates me to put the time towards the discipline of astronomy, while so many other matters are on the docket.

everything
     I need to keep on keeping up on the homework, quiz, tests. Keep on goin to classes and get good grades.
     I do all the reading and presentations ahead of time, as well as take detailed notes about them while I read. I review all my notes before tests/quizzes and check out all the posts online. I usually study for several days.

gotoclass
     I intend to keep attending class for the in-class activities and group work, in order to succeed. The in-class activities are very helpful for me, and I feel like they are great reviews for all of the material that we learn prior to the class.
     when I come to class I get answers to things I don't understand and can get clarification on them. this is vital to passing the class.
     It's something I do good so I'm going to keep doing it.
     I think one of the most important decisions a student can make in having a successful experience in this class is to show up. There is clarification of concepts, additional lessons on subject matter and group activities, all of which solidify the materials mysterious properties.
     i won't miss any new material being lectured and i won't miss out on in class points
     by going to class and doing the activities and taking the notes, it helps me fully understand what i completely understand and what i need to study some more.
     Well if I fail at doing anything else, at least by showing up I can kind of succeed.
     I think attending class is one of the most important things to keep doing, in order to succeed in this class. Everything is expanded on during class, questions may be asked & answered to help me understand what I find confusing. The In-class activities are very important to participate in, and help get a better understanding of what we're learning in class.
     I attend class every week and get a beneficial amount of information from every class period. I intend to keep attending.

inclassactivities
     ...as opposed to just letting teammates do the work.

homework
     The work online directly corresponds to what we learn in class. It helps to do the work. I can't imagine showing up to class without an idea as to what we are going to learn.
     I intend to keep doing the homework and extra credit assignments in order to ensure that I get as many points as I can before the tests.
     So far I've got into a good habit of filling out my online assignments. I can keep this up and keep doing well in this area.
     I intend to keep studying the practice quizzes and in class activities. I also intend to keep doing every homework assignment that is asked of us.
     I have yet to miss one and will keep on making sure that my record of completing homework stays on track.
     Keeping on top of homework and extra credit helps me keep up my points. Even if they are small, they start to add up.
     I intend to keep working on the reading assignments and study longer when we have quizzes.
     It is incredibly helpful to prepare for the next class and points are good.
     I intend to continue with keeping up on the reading assignments and homework that is given.
     I plan to keep doing my weekly reading assignments and homework. They are pretty easy points and get me prepped on what I need to know for the upcoming class.

payattention
     As long as I pay attention I can understand what we are covering, and if I get confused with anything I can pay attention to your explanations and understand things better!

presentations
     It gives thorough info through explanations and pictures

preview
     Since this class only meets once a week I need to stay on top of my reading and studying before class to be engaged and know what is going on so I can actually learn instead of having to be briefed on the material. It allows me to focus on actually learning the material rather than just hearing it for the first time.
     Taking notes before class is key (though a hard habit to keep up) seriously is the only reason I am doing well in this class. You understand so much more when you come to class, even if you think you know nothing!

reading
     I intend to keep trying to read entire chapters and summarize them.
     I need to keep reading the book chapters so I have a frame of reference for your lectures during class. Otherwise, I end up confused as to what we are talking about because I didn't read the material beforehand.
     I need to keep understanding the material and making sure i know the concepts
     Keeping up with the textbook readings
     Reading the assigned chapters and previewing the material in class helps you to really solidify learned material that we need in class activities and quizzes/tests.
     I think a huge step to success in any class is simply showing up! I really enjoy class and look forward to it every week.

review
     Studying everyday has allowed me to review and not forget anything since its my first astronomy class its very hard for me so I tend to be slow on knowing everything and getting help and studying everyday has helped. The reading assignments are clear examples of what we should know. The answers are easier to find than in the book.
     Reviewing and going over assignments really helps me remember the content. There is a lot of different information we need to remember and constantly reminding your brain of all of that information is and important part of learning the content.
     I like how I study after every class and I hope to continue with this.
     Before any test or quiz I review the power-points form that specific chapter or section to remind myself what the main topics are and to help me focus on what information I need to know before the Test or Quiz.
     When I re-read my notes, it helps my retention and usually there are more examples that I can relate to. The textbook contains a good amount of information and even though it is very dry and I usually don't read it until the night before or day of class.
     I need to go over the answers i got wrong on my quizzes and see what i didn't understand and also go over the ones i got right to make sure i understand.

rewritenotes
     If I keep rewriting my notes and color-cordinating them then it will help me to remember the material better. I rewrite my notes after class with different colors to help organize information and process it another time.

trying
     I am going to keep trying my best to succeed in this class. Graduation is only a few months away and I need to succeed in this class to get to the next step.
Quit word tags:
burningout
     I need to pace myself more when balancing my obligations. I tend to prioritize my other obligations in front of astronomy class. I think I do this for two reasons: 1) Class is very late in the day, after many of my other tasks. 2) The rewards from success in this class are less tangible than say, a paycheck or other resultant gratification. I do not pace myself sufficiently, and I expend most of my energy before Astronomy class. I need to manage my time and energy more effectively, and quit burning out.

distractions
     I tend to have a hard time focusing for long periods of time so I will get distracted with other things. I plan on trying to not do studying while doing other things and trying not to be distracted. Today I did most of my studying without getting distracted and it was so much better.

missingclass
     Obviously I make this class harder for myself by not even attending the class meetings.
     I really need to stop skipping class, I've only skipped twice but it's not good.

overthinking
     I have always hated test and I over study and go blank when a test comes up. I intend to stop overthinking and over studying.

procrastinating
     waiting until the last minute to do the online work isn't helping because by that point im extremely tired and it doesn't leave enough time to actually digest what im reading and learning. I've been doing the bare minimum and it is really showing up on my quiz scores and midterm. im only understanding half of the material. i know i can do better.
     I feel like I am doing pretty well in this class. I need to get back to my routine of getting the homework done each Thursday instead of waiting til Sunday or Monday though!
     To be successful, I need to stop procrastinating on my assignments. When I wait until the last minute to do my assignments, I rush through them and I don't focus on the material as much as I should. I can usually grasp the big picture, but I don't always process the details of the material.
     I intend to quit procrastinating because I seem to wait until the last second, leaving me no time to actually study the material.
     I intend to quit procrastinating on my reading material that is assigned to us through the homework. I eventually read the material, but because I procrastinate and wait till the last minute to read, I overwhelm myself.
     I often find myself doing the homework late at night. I need to get on top of the assingments and do them ahead of time.
     I always wait until the last minute to study and I don't retain that well.
     I need to stop putting off studying until the last minute. I'm very busy and I know this about my life. I need to take the time earlier in the week to complete assignments just in case I get called into work or have a sick kid and cant study.
     I usually am not a procrastinator, but I've been noticing that I've been getting into that bad habit. I intend to quit procrastinating about reading the chapters and studying for the quizzes/tests.
     i need to put homework assignments first and study right away instead of last minute
     Quit procrastinating homework and studying, so i can get even higher grades on quizzes and tests.
     When i procrastinate it tends to hurt me in the long run. Having to jam pack all the info about a quiz the day before is not cool.
     I tend to wait until Monday night's after I get out of night classes to read/study. I tend to be tired and less alert by then.
     I always forget to check the calendar before homework is due so from now on I will try to check it more often and remind my self to study with time
     I'm always stressed doing the readings the night that it's due and it would be a lot nicer and probably more beneficial to do it ahead of time.
     A lot of times I wait till the last second to do my assignments just because I know that I will get them done. But I do really need to change that and start completing my assignments ahead of time. It will likely relieve a lot of stress that I feel when it comes to school and not only improve my work, but lighten my stress load.
     I am going to quit waiting until the last minute to complete these online assignments!
     Sometimes I procrastinate to look at the material for a quiz test or lecture until the last moment so I don't get too much out of the preview. I also don't look into the material too deeply and only briefly go over it which I intend to better.
     I need to stay on top of studying and keeping the material fresh in my mind throughout the week. On weeks where I have been swamped with other class work from other courses I have tried to jam the information into my brain last minute and that is never a good idea.
     If I keep procrastinating the reading it will probably hurt me in the long run, I just don't like leaving reading to the last minute.
     I've noticed that I wait until the day before or day of when it comes to studying for the quizzes and I want to quit doing that. I haven't been doing as well on the quizzes as I would like to, and I think it's directly correlated with the fact that I wait until the last minute to study!
     I need to put more time and energy into doing the readings and fully investing myself in this class
     I often wait until the very last day to do my homework or study for the upcoming quiz/test. The scores have shown that this is not working out for me and I need to devote some more time to the class.
     I always procrastinate to the very last day to do the readings/homework. I need to stop procrastinating because I don't always have time to finish all of the readings, or homework, etc.
     I need to stop waiting till Tuesday night to do assignments.

skimming
     I think I need to read the chapters better to gain more info I tend to skim the book and pay more attention to the online slides. Just a lazy thing that I could probably stray away from.
     I would like to pay more attention to the actual reading assignments we are given. I started to just scan through the chapters and I want to take more time reading it like I did in the beginning.
     skimming isn't always the best thing to do. I notice when i do the surveys having to go back and re-read cause i will have missed something. I need to fully read the pages so i don't miss anything.
     If I stop skimming the material and start taking notes on the material that I read it'll help me understand concepts more.
     I will begin to read the chapters and sometimes ill leave out a couple chapters.

slacking
     if i study longer i feel like my quiz scores will be higher
     Not taking advantage of office hours, not throughly going over practice quizzes
     I've missed only one or two readings, but to miss more would negatively impact my grade for sure.The readings go along with our class activities and presentations, and they go along directly with the quizzes and tests.
     I intend to quit missing homework assignments and quit avoiding the reading. I am missing many homework assignments and it is harming my grade. Also it is very hard to take quizzes and test without reading the textbook.

sleeping
     There is just no more time for sleep, I can sleep when I am dead.

studyinginbed
     It is so hard to keep my eyes open sometimes, but extremely comfortable.
Start word tags:
askquestions
     I suppose I can start asking more questions about the material that confuses me. I just feel like the other students ask my questions before I do or they ask the questions more clearly than I can. Sometimes I have trouble getting my thoughts out.
     When I don't understand a subject I try to help myself in order to not ask for help but its okay to ask for help especially when I need it.

caring
     I know that if I am excited for something, I am less likely to expend all my energy at work (if I can help it). If I can get myself excited by something astronomical in the morning of class, I hope to maintain that thought throughout the day as a reminder to conserve some energy. In other words, I intend to start getting STOKED by astronomy.
     The more I invest my energy into doing the homework, the more I'll care about the subject matter and the better i'll do

earlier
     This way I can get a jump start on things and not feel so behind. My brain is so spot on in the a.m. I need to make a greater effort to promote greater retention in the early dawn.
     I need to start studying earlier for exams then the break before class.

focusing
     I try my best to stay focused all class period but a lot of times it is hard because the class is so long. I usually am focused so that I absorb all the content reviewed and talked about, but I could do a better job of maintaining that focus all class period.

gotoclass
     I want to start going to every class from now on.

participating
     In group activities, I'm very quiet. I don't always get completely involved, I let people take over if that's what they start to do. I need to start asking questions when I'm confused, instead of letting the "smart" kids do all of the work. I usually feel too embarrassed to say anything so I just stay quiet.

practicequizzes
     If I start the practice quizzes as soon as they are available then it'll help me with the quizzes and midterms more.

presentations
     Until now, I had been reading everything out of the book, but wasn't really digesting much. I started reading the blogs that are up online and they have been very helpful to me in grasping the lecture better.

prioritizing
     I intend to start planning my week better so I can get a better handle on my assignments.
     The only other evenings I have free are Friday and sometimes Saturday, Sunday. These are unrealistic times to study as "free" only refers to mandatory activities and not my social life.

reading
     I am going to take the book somewhere away from home so i have nothing else to do but read the book. hopefully.

rereading
     I could have benefited more if I reread certain book passages, especially the historical names.
     sometimes I know I need to reread things to retain them better but because of my schedule I don't always go back to get a better understanding

reviewing
     In order to be successful, I believe I need to start reviewing the online presentations of earlier subject materials before tests and quizzes. When I get questions wrong, they are mostly from the earlier subjects that we learn during the section, and I believe the online presentations are a great way to review the material.
     Going over previous reading assignments, practice quizzes and questions, presentations I need to start reading and relating things to my life or real world examples more during the week rather than Tuesday night when the homework is due and Wednesday when we have class.

starting
     I need to start on my projects.

studygroup
     I would like to talk about what I'm learning with someone like a study buddy or other Astronomy like minded group or individual. Tutor? This way I get to apply it and test out my new language.
     Studying with others is a great way for me to better understand what's going on in class. It makes it more fun, and I can ask other people if I am having trouble understanding something and help someone if they need help understanding. It really makes it so I have to understand what I am teaching or explaining.

studying
     I haven't been very consistent with reading the textbook before classes and I will start reading the chapters to better learn the material. I haven't studied for the class yet and it isn't making it impossible to take tests and quizzes but it would definitely make it easer if I did study. I need to allot myself time to re read the sections in the textbook and do the practice quizzes and practice exams.
     I thought i totally had it for the midterm, but when i looked at my grade i realized i should studied some more before the test. So i'm going to start studying more before test and quizzes.

studymore
     i need to start reading the book and go over the power point slides in more detail and let the info digest, and think about the information and ask questions in class. or when there is something i don't understand fully, i know that going over the chapter or slides will clean up my understanding a bit. i need to actually go over the information when a question rises.
     I intend to start studying more in order to ensure that I understand all the material and so that I can achieve better grades on the assessments and quizzes.
     I feel like I would be less stressed and would better understand the material if I just kept up on my reading and did it daily. It would probably help me in asking the right questions and not feel lost as often.
     I find myself surprised that I there is a quiz when I should have know about it. I need to remind myself and study more often for these things, or make myself a reminder for them.
     i need to read the textbook and power points more thoroughly and take notes
     Start studying after each class to better retain the new information, and be able to better retain all information when studying.
     I need to start really grasping the concepts with the reading assignments.
     More studying hope it will help test scores.
     I have been doing well on the quizzes and tests, but I honestly haven't studied much. I gotta keep that from going to my head and start studying as the material gets more complicated.
     I plan to make flashcards to study as well as doing all the examples and practices quizzes to prepare for the quizzes. This will also be better because I will be more prepared for class as well and have stronger ideas/understanding about the concepts.
     i will have a better grade in the class
     I plan to start spending more time on work for this class. I thought I was doing just fine in the beginning and was on top of the reading, etc. But then I started getting overwhelmed (not just this class but others and home life issues) and put some things on the back seat. I am going to spend more time for each class then I currently am.
     I want to make a point to take a look at my notes everyday even if it is brief. I have found this helps me with my memory and I do not get as stressed when it comes to tests.
     I want to start studying more efficiently. Whether that means studying with other peers or making flashcards, I think I need to come up with some more effective ways to learn the material.

takenotes
     It will help me remember the things I've read better I want to start to take notes on the reading and in class more, so that way it's a lot better and easier when I need to study.

Online reading assignment: stellar parameters (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 parallax, distance, apparent magnitude, absolute magnitude, Wien's law and the Stefan-Boltzmann law.


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 near by stars have a larger parallax and distant stars have a smaller parallax. The images provided really helped me make sense of it!"

"How everything is kind of backwards in astronomy, for example how the more magnitude a star has the dimmer it is. Also how if a star is a warmer color it's less hot then a cooler color star."

"How we're able to figure out so much about stars from Earth. Also I always thought the sun was the brightest star but it's not."

"How blue stars are hotter than red stars, because it makes sense when you think about fire. The reddish/yellow flames are less hot than the blue flames."

"That a star's the warmer a star gets the color shifts from red and yellow to white and blue. Red and yellow are the colors I would typically associate with the hottest stars, but it was interesting to see that it is the exact opposite."

"That we are going to learning about the different colored stars, their temperatures, and how bright/dim they get."

"That finding the size of a star depends on its luminosity, and to find this you can use math!"

"I found the relationship between luminosity, size and temperature interesting because I like math, especially when it relates to real-world examples."

"Everything about this chapter has been interesting. A little confusing, but interesting nonetheless. Stars are an incredibly fascinating and beautiful thing to learn about!"

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"I'm still not quite sure what a parallax is or how it works..."

"I found how to measure the distance of a star from Earth using parallax, to be quite interesting but just a little confusing. How does looking at the star from Earth while it's at one end of its orbit, then looking six months later tell you its distance?? I don't understand how the shift of the star in that specific amount of time, would tell you the distance."

"I think I need a little more clarification on the apparent and absolute magnitudes. Also the difference between the star sizes and their colors."

"I think the concept of parallax is interesting, but I'm a bit confused by the wording in the presentation. I understand its from two different points of view and you take it within a six months time difference but how do you know if it is closer or farther?"

"Why are brighter stars given negative numbers? Like what the heck how does that even make sense? I feel like that just makes everything way more complicated than it needs to be."

"That the lower the number, the brighter the star?"

"The magnitude scale kind of threw me off, because why is 'lots of brightness' considered a negative number. The second time I reread I just switched 'dim' for positive numbers (+6 being the dimmest shown) and 'bright' at –1!"

"I need some more help and explanation about the size of the stars and their temperatures. I kind of understand it but got a little lost."

"I found the Stefan-Boltzmann law to be confusing and hard. I'm not completely sure how to figure out all the different information. Like how to find the size from the luminosity and temperature. I get thats what you're supposed to do but I don't completely get how."

"I didn't find anything particularly confusing."

Explain how apparent magnitude and the absolute magnitude are defined differently.
"Apparent magnitude refers to how bright the star appears from Earth. However, a bright star can have a low apparent magnitude if it is very far from Earth. The absolute magnitude takes into consideration its distance, and measures how bright it would be if it were 10 parsecs away."

"Apparent magnitude is how bright the star appears from Earth, while the absolute magnitude is how bright the star appears at a standard distance of 10 parsecs."

"Apparent = 'as is.' This means that the distance you are to these stars is how you categorize their brightness. Absolute = '10 parsecs away.' This evens the scale by bringing both stars an equal distance away to see how their brightness measures side by side."

"Apparent is brightness of a star without compensating for distance while absolute compensates for distance."

"Apparent is how it appears from our view on Earth, absolute is what it actually is."

"I have no idea and need help with this."

Suppose the sun was moved to a distance of 10 parsecs away. As a result, its __________ magnitude would become dimmer.
absolute.  *************** [15]
apparent.  ******************* [19]
(Both of the above choices.)  ** [2]
(Neither of the above choices.)  [0]
(Unsure/guessing/lost/help!)  [0]

Rank the brightnesses of these stars (1 = brightest, 4 = dimmest; there are no ties), as seen from Earth.
(Only correct responses shown.)
1 (brightest): the sun, m = –27 [83%]
2: Canopus, m = –1 [83%]
3: Vega, m = 0 [81%]
4 (dimmest): Kapteyn's star, m = +9 [92%]

Rank the brightnesses of these stars (1 = brightest, 4 = dimmest; there are no ties), if relocated to 10 parsecs from Earth.
(Only correct responses shown.)
1 (brightest): Canopus, M = –3 [81%]
2: Vega, M = +0.5 [86%]
3: the sun, M = +5 [78%]
4 (dimmest): Kapteyn's star, M = +11 [89%]

Determine whether these stars get dimmer or brighter when relocated from their original positions to 10 parsecs from Earth.
(Only correct responses shown.)
The sun: gets dimmer [83%]
Canopus: gets brighter [75%]
Vega: gets dimmer [56%]
Kapteyn's star: gets dimmer [64%]

Rank the temperatures of these main sequence stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue main sequence star [89%]
Second hottest: white main sequence star [81%]
Third hottest: yellow main sequence star [89%]
Coolest: red main sequence star [94%]

Rank the temperatures of these supergiant and dwarf stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue supergiant [86%]
Second hottest: white dwarf [72%]
Third hottest: yellow supergiant [83%]
Coolest: red dwarf [86%]

Two stars (equally far away) have the same temperature, but one star is dimmer, and the other star is brighter. The __________ star will be larger in size.
dimmer.  ***** [5]
brighter.  ************************ [24]
(These stars would be the same size.)  * [1]
(Unsure/guessing/lost/help!)  ****** [6]

Two stars (equally far away) have the same brightness, but one star is cooler, and the other star is hotter. The __________ star will be larger in size.
cooler.  ********************** [22]
hotter.  ****** [6]
(These stars would be the same size.)  ** [2]
(Unsure/guessing/lost/help!)  ****** [6]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Please help!!! I am lost with this chapter with temperature/size and parallax!"

"I feel like I do understand most of these two chapters, but I think the lecture will solidify the information presented! Looking forward to lecture!"

"The lower the magnitude number, the brighter the star. Red stars are cooler, blue stars are hotter. Wtf?" (¯\_(ツ)_/¯)

"Will all these formulae be given on exams and/or in-class activities?" (No. But instead of memorizing equations, you just need to remember the logical steps used to compare stars' distances, brightnesses, sizes, and temperatures.)

"I don't understand the term 'blackbody.' It seems that they aren't black but have actual colors?" (A blackbody is a substance that doesn't have a color (either clear or black) at room temperature. If you heat it up so much that it begins to glow, then it will exhibit "blackbody radiation" (continuous spectrum light) that has a characteristic red, orange, yellow, white, or blue color. But only when it's hot.)

"I need more explanation on Stefan-Boltzman Law of stars please."

"Ok, can you talk a lot about star sizes and temperature please, I'm confusing myself."

"Will we go over and clarify how to determine the size of certain stars based on the information given like the questions above?" (Yes.)

"Why are the letters of the spectral sequence in that order? Is there meaning to it?" (No meaning (aside from whatever mnemonic you use to remember the sequence); they were presumably labeled alphabetically until they realized that sorting them by temperature will scramble the original alphabetical order.)

"The size of a star doesn't determine the temperature, the color does?" (Yes!)

"Sorry I'm legit too tired to give thoughtful answers, P-dog." ((-.-)zzz)

"Would you jump into a black hole if you had the chance?" (I would much rather watch someone else jump in. Far more entertaining.)

"What sparked your passion for astronomy? (Black holes. In the second grade I asked a University of Hawaii astronomy professor about what happens to stuff that falls into them.)

20170321

Online reading assignment: stellar parameters (NC 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 parallax, distance, apparent magnitude, absolute magnitude, Wien's law and the Stefan-Boltzmann law.


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.
"The size of the earth's orbit is the baseline to find the distance to a star. Makes sense since it gathers information when Earth is at either end of its orbit!"

"Parsecs, because now I know what Han Solo meant when he said the Millennium Falcon could complete the Kessel Run in less than 12 parsecs."

"I found the large difference between the apparent and absolute magnitude of the Sun to be very interesting. It's weird how the sun is actually dimmer then many stars, but it appears brighter because it is closer."

"I found how they ranked the brightness of the stars to be very interesting. Loved how you put it in perspective of how the Greeks used a similar ranking system. of 1st place through 6th place. Because you were right. At first looking at the numbers, it was confusing when seeing –27 through +6."

"The temperature of stars, red stars are cool and blue stars are hot. logically that is backward as red is related to hot and blue to cold."

"I always assumed white was the hottest star. I know beauty is in the eye of the beholder, but it's weird to be proven wrong."

"I found interesting that blue stars are hotter than orange or red stars. In a chemistry class years ago, we were told that the blue part is the hottest in a flame and I guess that would apply to other things in the universe. I shouldn't have been surprised that the same is true for stars."

"I found color to size ratios interesting because I never thought of a small, hot star and a large, cool star having the same luminosity."

"It was interesting to learn that white dwarf stars are around the same size as earth. I previously didn't know any stars were that small."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The labeling of the brightnesses were weird to get used to but honestly not that bad."

"What the differences between absolute and apparent magnitude mean."

"The temperatures of the sequence stars was especially confusing to me. The diagram in the chapters didn't help me at all, I couldn't figure out how to read the diagram. (Edit: After reading your presentation and looking at the diagram you gave, it made a lot more sense to me!)"

"I found that the luminosity equals size times temperature4 to be somewhat confusing. I am hoping we can work on some more problems that would help me understand those a little bit better and how to classify the stars."

"Star sizes relative to their temperature and color. it was confusing because i didn't have enough time to go over the slide."

"The dwarf stars and supergiants and main-sequence stars; I didn't quite grasp what those phrases meant as far as temperature."

"I found this section quite easy to follow in all honesty."

Explain how apparent magnitude and the absolute magnitude are defined differently.
"Apparent magnitude is how the star looks from earth, while absolute is how it really is."

"Apparent measures a stars brightness based on how they seem to us without taking into account how far away the star is. Absolute magnitude takes into account the distance."

"Apparent magnitude is how bright a star appears to you on Earth. Absolute magnitude is when you know the distance and use math to calculate how bright a star would be at 10 parsecs away."

"Absolute magnitude is a standard measure (10pc) used to compare stars because their different distances from us change their appearance. Apparent magnitude is how bright the star looks to you on earth and doesn't take into consideration the distance from you or other stars you are comparing it to."

"Apparent is as seen by an observer on earth and is not an accurate way to measure brightness of stars, absolute helps to see when stars are actually dimmer."

"Unsure/guessing/lost/help! I understand the brightness of a star, but I'm not sure I really grasp the difference between apparent magnitude and absolute magnitude."

Suppose the sun was moved to a distance of 10 parsecs away. As a result, its __________ magnitude would become dimmer.
absolute.  ******* [7]
apparent.  *********** [11]
(Both of the above choices.)  * [1]
(Neither of the above choices.)  * [1]
(Unsure/guessing/lost/help!)  [0]

Rank the brightnesses of these stars (1 = brightest, 4 = dimmest; there are no ties), as seen from Earth.
(Only correct responses shown.)
1 (brightest): the sun, m = –27 [80%]
2: Canopus, m = –1 [75%]
3: Vega, m = 0 [85%]
4 (dimmest): Kapteyn's star, m = +9 [75%]

Rank the brightnesses of these stars (1 = brightest, 4 = dimmest; there are no ties), if relocated to 10 parsecs from Earth.
(Only correct responses shown.)
1 (brightest): Canopus, M = –3 [70%]
2: Vega, M = +0.5 [80%]
3: the sun, M = +5 [75%]
4 (dimmest): Kapteyn's star, M = +11 [75%]

Determine whether these stars get dimmer or brighter when relocated from their original positions to 10 parsecs from Earth.
(Only correct responses shown.)
The sun: gets dimmer [75%]
Canopus: gets brighter [70%]
Vega: gets dimmer [65%]
Kapteyn's star: gets dimmer [65%]

Rank the temperatures of these main sequence stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue main sequence star [75%]
Second hottest: white main sequence star [60%]
Third hottest: yellow main sequence star [80%]
Coolest: red main sequence star [75%]

Rank the temperatures of these supergiant and dwarf stars (1 = hottest, 4 = coolest; there are no ties).
(Only correct responses shown.)
Hottest: blue supergiant [75%]
Second hottest: white dwarf [60%]
Third hottest: yellow supergiant [75%]
Coolest: red dwarf [75%]

Two stars (equally far away) have the same temperature, but one star is dimmer, and the other star is brighter. The __________ star will be larger in size.
dimmer.  **** [4]
brighter.  *************** [15]
(These stars would be the same size.)  [0]
(Unsure/guessing/lost/help!)  * [1]

Two stars (equally far away) have the same brightness, but one star is cooler, and the other star is hotter. The __________ star will be larger in size.
cooler.  ********* [9]
hotter.  ********* [9]
(These stars would be the same size.)  ** [2]
(Unsure/guessing/lost/help!)  [0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I will start implementing new study techniques soon."

"Does the location of our solar system in the universe matter? If our whole solar system was moved, could the conditions of the surrounding universe make everything unstable?" (Yes, especially if we had closer neighboring stars, they could disrupt the cloud of comets surrounding the sun at the very edge of our solar system, making it much impact events on Earth much more frequent.)

I asked my parents where baby planets come from, and they said. When a daddy star and a mommy star fall in love, there is some really hot action. Then their babies get thrown all over the place. Is this true?" (We'll look at the "birds and the bees" of how stars are born next week.)

"How can we know how big stars are?" (We'll talk about this specifically on Thursday. Short answer: you calculate the size from measurements of their brightness and color.)

"I'm confused about white dwarfs. They are white which make me think they are hot, but they are dying, so are they cooler than other white stars?" (They are white and very hot, but yes, they are dying in the sense that they no longer can produce energy. So a fresh white dwarf will be white-hot, but will gradually cool off (over a very, very long time) and to become a cooler "black dwarf." However, this process takes such a long time that no white dwarf has yet to become a black dwarf, as they manage to hold on to their heat really well.)

"Between the two Cuesta campuses, is one better than the other for using the telescopes in regards to light pollution, turbulence, etc.?" (North County campus is better in terms of having less light pollution (although the new building may change that), and especially better in terms of not having the marine fog layer roll overhead on most nights.)

"Could please briefly go over the parsecs, apparent and absolute magnitude, and how to find out which star is brightest/how to find out if it's brightest at 10 parsecs? I can't figure out how to calculate these things." (Yes, we will go over those things.)

"Stars are badass :)"

"It's kind of driving me crazy that our homework is further ahead than our quizzing...I am comfortable at the pace we are moving along with the homework but I would have an easier time if the quizzes were current with the reading/homework." (This is somewhat deliberate in order to give you enough time after seeing the material in class to go over it again before the quiz. But be careful of what you wish for--the cycle between homework and quizzes will get shorter as the end of the semester approaches.)

"In math, negative numbers are always smaller that positive numbers. When it comes to stars brightness, why do stars with negative numbers have a greater brightness than stars with positive numbers?" (Because stars were ranked like runners in a race, where "1st place" is better (brighter) than "2nd place," etc. Or like in a judged contest where "grand prize" is better than "1st runner up," "1st runner up" is better than "2nd runner up," etc. (So would that make the "grand prize" the "zero runner up?"))

"I feel like when I read the material in the book I am confused often. But when I look at your blogs it makes more sense and appears more practical to understand."

20170320

Physics quiz question: voltmeter reading along "top" of series circuit

Physics 205B Quiz 5, spring semester 2015
Cuesta College, San Luis Obispo, CA

An ideal 4.5 V emf source is connected to an ideal voltmeter, a light bulb, and two resistors, as shown at right. The voltmeter reading is:
(A) 0.26 V.
(B) 0.39 V.
(C) 2.1 V.
(D) 2.4 V.

Correct answer (highlight to unhide): (D)

Since the ideal voltmeter has an infinite resistance, no current flows through it, and only along the lower loop of the circuit (through the ideal emf source, the top left resistor, the light bulb, and then through the lower right resistor). Since the resistors and light bulb are wired in series, the equivalent resistance of the circuit is just the arithmetic sum of their individual resistances:

Req = 8.0 Ω + 1.5 Ω + 8.0 Ω = 17.5 Ω.

From Ohm's law, the current flowing through this simplified (one ideal emf and one equivalent resistor) is:

I = ε/Req = (4.5 V)/(17.5 Ω) = 0.2571428571 A.

Starting from the contact on the left, the difference in voltage detected by the voltmeter is the drop due to the top left resistor plus the drop due to the light bulb:

V = (–I·Rresistor) + (–I·Rlight bulb),

V = –I·(Rresistor + Rlight bulb),

V = –(0.2571428571 A)·(8.0 Ω + 1.5 Ω) = –2.4428571429 V,

or to two significant figures, the voltmeter reading is 2.4 V.

(Response (A) is the current I = ε/Req flowing through the circuit; response (B) is the voltage drop ∆V = I·Rlight bulb of just the 1.5 Ω light bulb; response (C) is the voltage drop ∆V = I·Rresistor of just the 8.0 Ω resistor.)

Sections 30882, 30883
Exam code: quiz05aL7y
(A) : 16 students
(B) : 6 students
(C) : 9 students
(D) : 16 students

Success level: 34%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.62

Physics quiz question: ammeter readings in circuit perimeter

Physics 205B Quiz 5, spring semester 2015
Cuesta College, San Luis Obispo, CA

Two ideal ammeters are connected to circuit with a switch, an ideal 1.5 V emf source, a light bulb and a resistor, as shown at right. While the switch remains open, the __________ ammeter has a higher reading.
(A) top.
(B) bottom.
(C) (There is a tie, where both ammeters have a zero reading.)
(D) (There is a tie, where both ammeters have a finite, non-zero reading.)
(E) (Not enough information is given.)

Correct answer (highlight to unhide): (C)

While the switch remains open, the emf is isolated from the circuit, which is completed around its perimeter with just a light bulb, resistor, and two ammeters without any source of emf. Thus no current will flow through outer perimeter of this circuit, such that both ammeters will read zero.

Sections 30882, 30883
Exam code: quiz05aL7y
(A) : 2 students
(B) : 3 students
(C) : 37 students
(D) : 5 students

Success level: 79%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.32

20170317

Astronomy current events question: microbes could survive on Mars?

Astronomy 210L, spring semester 2017
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)
Charles Q. Choi, "Microbes Could Survive Thin Air of Mars" (January 18, 2017)
astrobiology.nasa.gov/news/microbes-could-survive-thin-air-of-mars/
Researchers propose that methane-producing organisms could survive on Mars, based on similar Earth microbes surviving:
(A) in deep ocean vents.
(B) similar conditions in a laboratory.
(C) aboard the Curiosity Mars rover.
(D) inside meteorite samples.
(E) underneath Siberian permafrost.

Correct answer: (B)

Student responses
Sections 30679, 30680
(A) : 5 students
(B) : 16 students
(C) : 0 students
(D) : 8 students
(E) : 2 students