20180221

Online reading assignment: runaway planets, jovian planets, and dwarf planets (oh my!) (SLO campus)

Astronomy 210, spring semester 2018
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 runaway planets (Venus and Mars), jovian planets (Jupiter, Saturn, Uranus and Neptune), and the dwarf planets (and the International Astronomy Union classification scheme).


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 reasons why Pluto was downgraded from being a planet to a dwarf planet."

"Venus in particular--being covered by a fresh crust over and over is pretty fascinating, and the question of whether or not its core still has what it takes to erupt again seems especially interesting to think about."

"I enjoyed the gopher analogy relating to volcanic activity on Venus, it was interesting to imagine. I also really liked the example of convection currents demonstrated by the coffee and cream example, that was really cool."

"The runaway planets: Venus and Mars. Also how bad the environment of our planet is, and how my history professor has the guts to stand in front of the class to say that he does not believe in global warming."

"I thought it was interesting to see what characteristics a planet needs to qualify as a planet. It's something that I rarely think about and getting an explanation for it was interesting to learn about."

"I found it very interesting that despite being about half of the size of Earth, Mars has relatively the same amount of land cover as Earth."

"Mars as a 'runaway refrigerator'--it really illustrates just how much a planet can be changed due to an imbalance of its carbon cycling. It is also interesting to me because it really brings me back to the lecture last week about the fact that Earth's oceans may nearly be at full capacity when it comes to soaking up carbon dioxide from our atmosphere. It makes me wonder what the changes brought onto Earth would really be if we were to never find a solution to this issue. So I suppose we can say that this is a topic that is both interesting and depressing to me."

"I had no idea that Mars possibly could have enough water to fill oceans! And that it still has water (permafrost.)"

"That the planets with the most mass are the ones that produce and retain the most atmosphere. It makes perfect sense, but I had never really thought of it before."

"I have enjoyed learning more about greenhouse gases and the effects they have on a planet and why. Mostly due to the fact that it has dominated our news about Earth's atmosphere and its rising temperatures. I now have a better grasp and understanding to it all. Still scary but knowledge is power especially in this case."

"I loved getting to learn about the different atmospheres of the planets. I thought that it was so cool to learn how Venus and Mars are so similar to Earth but still so different."

"Knowing which parts of a planet are older or younger is interesting. I think its interesting because we have never been to these planets, yet we can learn a lot about them and others just based on our observations."

"I found the explanation of why Pluto is no longer considered a planet interesting. I guess it is interesting because as a kid, I learned it was a planet. Its just crazy that it no longer is."

"PLUTO IS NOT A PLANET???? I knew this but I'm still mad about it. But on a serious note, I found the sizes of the planets very interesting and shocking."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The relationships between planet mass, outgassing, and atmosphere density. I get how they are correlated to each other, but I would like to know why this happens."

"The layers of clouds in the gas giant atmospheres--I'd like to go over more on how they form different thicknesses and color."

"I am finding myself struggling to wrap my mind around issues regarding the atmosphere cycle charts for Earth, Venus, and Mars. In the presentation about the runaway planets, it mentions at the end that we will be doing an in-class activity requiring us to be able to fill in two pages on the histories and greenhouse cycles for Venus and Mars. Even after going through the presentation and the reading assignment I am finding myself a little confused on how to do this properly. I know that this old brain can do it, but I might need a little more instruction on how to do so."

"I'm not sure how the whole atmosphere plus distance from the sun works. It is confusing to me because I thought that Venus was too close to the sun to possibly be a livable planet, but now I'm reading that the planet's amount of greenhouse gasses also affects the amount of heat it takes in. this is at least what I have comprehended, but I am not sure if I comprehended correctly."

"How Venus could be so different from Earth even though it is similar in size and not that much closer to the sun."

"I thought it was slightly confusing on how one of the steps of categorizing solar system objects is whether it has a round shape compared to a lumpy potato shape. I peronally don't get why that has to be a factor aside form it having enough gravity and force to push itself together."

"I find myself getting a little mixed up on how to classify stuff. Like the shape thing. How round is round enough?"

"The only thing I am confused about is the fact that we haven't done more extensive research as to how our planets were formed in the ways they were, and why they are configured in the way they are. It seems that finding the answer to these questions would help us better understand not only our own solar system, but the infinite amount of others as well."

"I just really like Pluto, and I really wish it could have stayed a planet. I find it confusing that the people who determine whether or not a planet is a planet do not love Pluto enough to keep it a planet. #vivalapluto"

Identify the relative amounts of these characteristics for Venus, compared to Earth. (Only correct responses shown.)
Interior core heat, today: about the same as Earth [29%]
Geologic activity, today: less than Earth [63%]
Volcanic outgassing, up until now: about the same as Earth [42%]
Heat from the sun: more than Earth [76%]
Amount of atmosphere, today: more than Earth [63%]

Identify the relative amounts of these characteristics for Mars, compared to Earth. (Only correct responses shown.)
Interior core heat, today: less than Earth [84%]
Geologic activity, today: less than Earth [71%]
Volcanic outgassing, up until now: less than Earth [71%]
Heat from the sun: less than Earth [82%]
Amount of atmosphere, today: less than Earth [87%]

Which jovian planet has the coolest interior temperatures?
Jupiter (most massive).   * [1]
Saturn (most prominent rings).   * [1]
Uranus (least active weather patterns).   ***************** [17]
Neptune (farthest from the sun).   **************** [16]
(Unsure/guessing/lost/help!)   *** [3]

I believe Pluto should be a planet.
Strongly disagree.   ** [2]
Disagree.   **************** [16]
Neutral.   ************** [14]
Agree.   *** [3]
Strongly Agree.   *** [3]

Briefly explain your answer to the previous question (whether Pluto should be a planet).
"Because Pluto is awesome. Viva la Pluto!"

"I don't think Pluto should be a legitimate planet because it doesn't completely dominate its solar orbit, but instead shares its path with several other objects of similar size and roundness."

"According to the IAU classifications it is a dwarf planet, which I understand though secretly I still enjoy thinking of it as a planet in it's own right."

"I am 100% neutral about the idea of Pluto be a planet. I am for it because growing up we included Pluto in our learning curriculum when it came to the solar system and it’s weird to teach the future generation that it isn't. Scientifically speaking Pluto is smaller than any other planet and even the moon yet even though it has an orbit shares it with other Kuiper belt objects. And since I had been visited by only one spacecraft in 2015 so far I just believe there's not enough information or knowledge on it."

"It does not really revolve around the solar system with a regular pattern like the other planets."

"I feel bad for Pluto."

"I can see why there would be an argument for Pluto being a planet, however I more strongly agree that it shares an unusual orbit with other similar objects making it a dwarf planet."

"I understand the reason it was deemed to not be a planet, but since I am not the most educated in this topic just yet, I feel very neutral in this argument."

"Pluto was once considered to be a planet, so I do not think that it's privilege should be revoked."

"According to the textbook, one of the IAU's criteria for official 'planet status' requires objects to be of a large enough mass to dominate its orbital regions, clearing said region gravitationally of most other objects. Pluto has failed to become gravitationally dominant, and thus fails to meet the IAU's standards for planet status."

"I'm not sure why it isn't a planet."

"To be a planet it needs to gravitationally clear away other objects from its orbit but Pluto stayed within the Kuiper belt with other icy bodies. So it is a dwarf planet."

"I'm not sure on which stand I side with on this topic. Since Pluto classifies as neither a jovian or terrestrial, I don't believe it's a planet."

"When I was in elementary school, I was taught that Pluto was a planet. It's weird to know now that it's considered a dwarf planet now."

"I understand and agree with the reasons why it is not consider it is a planet, but I also think it just should have stayed a planet."

"I do agree that we should create certain labels on how and what makes a planet, if we never did that then we couldn't be able to draw boundaries and lines when talking about our solar system."

"They classified Pluto as a planet, we grew up knowing it... You can’t just take that away."

"I thought I read that the reason it is not a planet is because it does not have a moon."

"It follows an orbit with tons and tons of other planet-type objects, if pluto were considered a planet than so would those random objects too."

"There are objects in our solar system bigger than it that aren't planets."

"It is now considered a dwarf planet because of its size, and because of the discovery of different worlds in the Kuiper belt."

"Pluto does not fit the current definition for a planet. However changing the definition also complicates things. It is hard to say."

"Just because it has been considered a planet for this long, does not mean that it should still be since science has proven it to not be a planet. That being said, when I think of Pluto I still think of it as a planet so I do not know exactly where I stand."

"I do not believe that Pluto should be a planet because according to IAU's criteria it must be able to dominate and gravitationally clear its orbital region, and Pluto does not. If we let Pluto be considered a planet even though it doesn't fulfill this criteria, what other things similar to Pluto would we have to consider to be planets?"

"I think that planets should be grandfathered in although it does make sense why Pluto is not a planet."

"Even though I would want Pluto to be a planet according to what classify a planet Pluto no longer makes the cut."

"I do not agree that it falls inside the criteria needed to be a planet, but because we can still learn a lot from its existence we should honor its original title of planet."

"It doesn't fit within the definition of a planet, but fits within the definition of a dwarf planet."

"Pluto does not dominate its orbit, so it should not be a planet."

"Because it only satisfies two of the three criteria to be considered a Planet. Pluto does not dominate its own orbit therefore making it a dwarf planet."

"I do not believe that Pluto is a planet because it does not have an independent orbit around the moon, it orbits with many other Pluto-like masses. If we want to consider Pluto a planet we must then consider all of these similar-mass objects."

"It doesnt really matter whether or not Pluto is a planet to me."

"I want it to be a planet because in my childhood it was a planet. As an adult I understand the reasons it is not considered a planet."

"I really want Pluto to be a planet but I understand the scientific reasons why its not."

"If it doesn't meet the right standards to be a planet then its technically not a planet but maybe one day they can take a second look at the planet and rethink their decision."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"If we continue to treat our planet the way that we have been doing, will we look like Venus on day?" (We certainly could, although I'm hoping we would care about our planet to not do that to ourselves.)

"Is there anything we could do to Venus to change the atmosphere to maybe fix it?" (According to Wikipedia, there are a lot of different ideas on how to do this, but it would probably be easier to fix Earth first than to try to fix Venus.)

"Are there any tips you can offer in regards to mastering how to fill out the atmosphere cycle charts, or is it just a matter of brute memorization?" (In class tonight we'll go over a "big picture" narrative to make those charts make sense.)

"If Uranus was struck to cause it to rotate on its side, wouldn't astronomers see evidence of that?" (There are indirect clues for that, but there isn't any definitive evidence (yet) of that theory, at least until we get a better data on what's going on deep inside that planet.)

"How can the temperature of the terrestrial planet cores be recorded? Or even more so, the jovian planets?" (For terrestrial planets, the magnetic fields are created by the circulation of the core and mantle--hot core planets like Earth have strong magnetic fields, cooled-off core planets like Mercury and Mars have weak magnetic fields, so measuring the magnetic fields of a terrestrial planet (by orbiting it) is one way to determine the temperature of its core. Determining the temperature of jovian planet cores is more straightforward, you would only need an infrared telescope to measure the heat directly given radiated outwards from these gas giants.)

"In the book it says that Venus has a similar average density to Earth, but then later it says that Venus is 90× denser than Earth?" (The planet Venus itself is nearly the same density as Earth, but Venus' atmosphere is 90× thicker than Earth's atmosphere.)

"How about we let Pluto be a planet again?"

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