Astronomy current events question: comet 67P/Churyumov-Gerasimenko color changes

Astronomy 210L, spring semester 2020
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!)

Gianrico Filacchione, Fabrizio Capaccioni, and Matt Taylor, "Rosetta and the Chameleon Comet" (February 5, 2020)
esa.int/Science_Exploration/Space_Science/Rosetta/Rosetta_and_the_chameleon_comet

The European Space Agency's Rosetta spacecraft images show how comet 67P/Churyumov-Gerasimenko changed __________ as it passed near the sun.
(A) colors.
(B) density.
(C) trajectory.
(D) solar flares.
(E) rotation rate.

Correct answer: (A)

Student responses
Sections 30679, 30680
(A) : 36 students
(B) : 1 student
(C) : 0 students
(D) : 1 student
(E) : 0 students

Astronomy current events question: atom probe tomography of moon dust grain

Astronomy 210L, spring semester 2020
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!)

Natalie Dalea, "One Small Grain of Moon Dust, One Giant Leap for Lunar Studies" (February 4, 2020)
fieldmuseum.org/about/press/one-small-grain-moon-dust-one-giant-leap-lunar-studies

Atom probe tomography analyzed moon dust composition, using a __________ to release atoms one-by-one into a detector.
(A) laser.
(B) water jet.
(C) magnet.
(D) vacuum pump.
(E) spark generator.

Correct answer: (A)

Student responses
Sections 30679, 30680
(A) : 26 students
(B) : 1 student
(C) : 5 students
(D) : 3 students
(E) : 2 students

Astronomy current events question: Pluto's "icy winds"

Astronomy 210L, spring semester 2020
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!)

Lauren Lipuma, "Pluto's Icy Heart makes Winds Blow" (February 4, 2020)
news.agu.org/press-release/plutos-icy-heart-makes-winds-blow/

Computer models explain how __________ on Pluto's heart-shaped Tombaugh Region may affect regional wind patterns.
(A) ice volcanoes.
(B) vapor geysers.
(C) methane pools.
(D) frozen nitrogen.
(E) erosion canyons.

Correct answer: (D)

Student responses
Sections 30679, 30680
(A) : 2 students
(B) : 1 student
(C) : 0 students
(D) : 35 students
(E) : 0 students

Physics quiz question: object inside converging lens focal point

Physics 205B Quiz 2, spring semester 2020
Cuesta College, San Luis Obispo, CA

An object 1.0 cm in height is placed 16 cm in front of a converging lens with a focal length of +25 cm. The resulting image is:
(A) upright, diminished.
(B) upright, enlarged.
(C) inverted, diminished.
(D) inverted, enlarged.
(E) (No image would be produced.)

Correct answer (highlight to unhide): (B)

Solving for the location of the image d_i:

(1/d_o) + (1/d_i) = (1/f),

(1/d_i) = (1/f) – (1/d_o),

(1/d_i) = (1/(+25 cm)) – (1/(+16 cm)) = –0.0225 cm^–1,

d_i = 1/(–0.0225 cm^–1) = –44.444... cm,

where the negative sign by convention makes this a virtual image located to the right side of the lens (the side of the lens opposite the original object). The linear magnification m is given by:

m = h_i/h_o = –d_i/d_o = –(–44.444... cm)/(16 cm) = +2.777...,

which means that this virtual image is upright, due to the positive sign, and is enlarged, being about 2.8 times the size of the original object.

Sections 30882, 30883
Exam code: quiz02B3rD
(A) : 1 student
(B) : 21 students
(C) : 3 students
(D) : 10 students
(E) : 0 students

Success level: 60%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.83

Physics quiz archive: lenses, optical instruments

Physics 205B Quiz 2, spring semester 2019
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz02B3rD



Sections 30882, 30883 results

0- 6 :
7-12 :	*** [low = 7]
13-18 :	*****
19-24 :	********************* [mean = 21.5 +/- 5.2]
25-30 :	****** [high = 30]

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

Astronomy 210, spring semester 2020
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 descriptions of other terrestrial planets, which makes it just more of a miracle that Earth is capable of hosting life, when others with just some things a bit wonky are inhospitable."

"How Venus is 95% of Earth's diameter but it's very different from Earth. It has volcanos, lava flows, and impact craters, in a deep hot atmosphere."

"I don't know why but I always looked at Venus and thought 'huh, she's kinda pretty.' I knew she was made of gas. But I didn't know she was hot enough to melt lead, smells bad and that the greenhouse effect is much worse there."

"I found it interesting that Venus had geological features (such as coronae) unique to anywhere else in the solar system. I had some curiosity about studying planets and the characteristics that make them unique (such as Uranus' reverse rotation). This information can help us compare our own planet with others and understand geologic activity elsewhere in the solar system."

"I found the ability to determine certain areas of a planet as new or old very fascinating. Being able to figure out which parts of the crust are fresh, or how long it's has been there is interesting to know. Also I really enjoyed the thick gravy skin analogy in describing hot spots."

"I liked learning about the surface features of Venus and Mars. I also like seeing the different things the other planets and Earth have in common. "

"I found learning about the greenhouse factors on Venus and Mars interesting because I have heard Earth's greenhouse effect discussed often but never considered other planets' greenhouse effects."

"Reading about the conditions of Mars was interesting to me. It's a lot less inhabitable sounding that it's been made to seem."

"I found the amount of water that is predicted to be on and within Mars interesting. Especially the early stages of Mars where there were large bodies of water."

"These were the most interesting points I read: (1) Venus is a hot lava volcano planet. (2) Liquid water on Mars can't exist because it would boil away instantly. (3) Jupiter has four large moons and at least 60 small moons. (4) Saturn's rings are ice. (5) Pluto has five moons."

"I found the part about water on Mars the most intriguing. the fact that there is still frozen water on the poles, as well as signs of liquid water on the surface, is really cool and makes me wonder what else we may have yet to find on Mars."

"I found it super-interesting that none of the jovian planets have a surface that you would be able to walk on, because they are hydrogen-rich planets and are have lots of water in both solid and liquid."

"I found it interesting that Saturn's rings are actually composed of ice particles. I never knew this before, so I found it interesting to actually be told what exactly it's composed of and why."

"One thing I found interesting was that when the sun warns the clouds, they tend to rise higher in the sky on Jupiter. However, Saturn doesn't receive as much sunlight so the color and clouds are lower ant faint."

"I found Jupiter and its atmosphere extremely interesting, I just think that it is crazy that Jupiter is mostly composed of liquid metallic hydrogen."

"How Uranus has the coldest interior temperature of the jovian planets."

"I found the information about the planets interesting. I'm especially interested in planetary classification and excited to dive deeper into it."

"I found the extreme differences between the planets to be very interesting. I remember learning a lot 'about' the planets in grade school. By a lot, I mean we learned how many there are (were, RIP Pluto) and memorized mnemonic devices for their order. However, I don't recall focusing much on their matter or other specifics or most importantly, what these mean for their history. I enjoyed getting to know more about the planets and what is important about this hints to how they came to be."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"Nothing was specifically confusing, but I can feel that I will have a hard time remembering the different aspects of greenhouse gases and how they relate to planets. (Though the turkey/Cornish hen image does help a ton!)"

"I think it's kinda weird and confusing how the oceans dried up on the other planets and how we know they were there at one point. Why did they disappear or evaporate?"

"I was confused about how Mars and Venus compared to Earth in terms of geologic activity and core features. I felt pretty clear about how each planet retained heat but was unsure about these two particular things."

"I had trouble understanding the 'runaway atmospheres.' I can't seem to grasp how each planets greenhouse cycle was broken, or how the breaking of each cycle began in the first place. The order of events in which the cycle proved to be broken was difficult to understand."

"How the greenhouse effect works. I was trying to figure out how mass and other things that affect it."

"I found it confusing that the textbook said Mars had no water, but then proceeded to say that the water is found through the permafrost and in the polar caps. It was very confusing, because it felt like they kept contradicting themselves."

"How if there is water on Mars it boils away because of the low air pressure, but the only water found on Mars is like permafrost."

"I didn't completely understand the 'Cooper Cooler® effect.' I found this confusing because I didn't fully understand what the it was used to explain."

"I would like to understand jovian planets better and what determined a planet to be a ice or gas giant, and greenhouse factors for the terrestrial planets."

"The different clouds and gas situations with the jovian planets. I think I just need better visuals. "

"Dwarf planets and how are they formed."

"It wasn't quite clear to me what makes something a planet versus a dwarf planet."

"I don't understand why scientists reclassified Pluto. What new criteria did they add that suddenly knocked Pluto down to being a dwarf planet?"

"Trying to figure out whether or not Pluto is a planet was confusing. there are a few things that define a planet and Pluto seems to fit so but not all."

"There wasn't much to be confused about because it was mainly just describing the planets."

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 [26%]
Geologic activity, today: less than Earth [47%]
Volcanic outgassing, up until now: about the same as Earth [33%]
Heat from the sun: more than Earth [86%]
Amount of atmosphere, today: more than Earth [62%]

Identify the relative amounts of these characteristics for Mars, compared to Earth. (Only correct responses shown.)

Interior core heat, today: less than Earth [76%]
Geologic activity, today: less than Earth [68%]
Volcanic outgassing, up until now: less than Earth [62%]
Heat from the sun: less than Earth [85%]
Amount of atmosphere, today: less than Earth [85%]

Which jovian planet has the coolest interior temperatures?

Jupiter (most massive).	* [1]
Saturn (most prominent rings).	[0]
Uranus (least active weather patterns).	************** [14]
Neptune (farthest from the sun).	************* [13]
(Unsure/guessing/lost/help!)	****** [6]

I believe Pluto should be a planet.

Strongly disagree.	* [1]
Disagree.	************ [12]
Neutral.	************ [12]
Agree.	******** [8]
Strongly Agree.	* [1]

Briefly explain your answer to the previous question (whether Pluto should be a planet).

"I am not too sure what to think!"

"We should continue studying Pluto."

"It was once a planet and has the qualities of a dwarf planet so I think it should still be considered one."

"Although my childhood consisted of identifying Pluto as a planet, there are much smarter people than me, that have established the necessary guidelines for being a planet. They have determined Pluto does not qualify, and I have no grounds to stand against their expertise."

"I disagree that Pluto should be a planet because it's out of the orbiting rings."

"It should be considered a planet due to it still being in the solar system and that it was one of the first planets they spotted."

"Growing up, I was always told that Pluto was a planet. So it is a little confusing why the scientists reclassified it."

"Just always remember being taught the solar system when I was younger and learning all the planets and now being taught that Pluto isn't a planet just brings out the little kid in me wanting it to be classified as a planet again."

"I am a little on the fence on this one, but since it is not similar to the jovian or terrestrial planets, and there is other icy bodies orbiting beyond Neptune, some more massive then Pluto, it seems fit that it would not be considered a planet unless other ones were also."

"Honestly I can not say I would need more peoples point of view on whether it is a planet or not."

"I am not sure on the difference between a planet and at what point its a dwarf, so I cant say for sure."

"I believe scientifically that Pluto is a dwarf planet but it will always be a planet in my heart."

"I hate to say it this way, but I guess I just don't really care if it's considered a planet or not--labels, ya know?"

"I agree because it has an orbit, has moons, and has different gasses on its surface. Just because it's tiny and a little farther out there, shouldn't discard it from being a planet. It's hard to make a decision on an issue that was decided on by scientists much more advanced that I will ever be, and overturned as well."

"They can't make Pluto a planet and then take the title away. Plus it's still a dwarf planet."

"It is one of many objects in the outer belt of the solar system, so if Pluto should be considered a planet than so should the others."

"I don't believe that it qualifies as a planet because of the fact that it is so small, it doesn't even qualify as a jovian planet, and its orbit can bring it closer to the sun than Neptune at times. That doesn't seem like any type of orbit of a planet in our solar system, therefore I don't think ti should qualify as one. Even if it has its own moons."

"Too small to be a planet and doesn't have too many characteristics of a planet."

"I don't really care either way."

"No Pluto is too small and lacks gravitas."

"It is a dwarf planet, not big enough to be move stuff, but large enough to be a something. It is not big enough or diverse enough to be able to say that it is a planet."

"Personally I don't mind Pluto can be who he wants to be but scientifically speaking he can't really be classified as a planet."

"I feel that since Pluto is somewhat planet like but seems to be an outlier and differ in some aspects that it should remain as it is. Why change it after all this time if it is fine the way it is. They clearly made that decision for a reason."

"Pluto fits the definition planet: a celestial body moving in an elliptical orbit around a star."

"While Pluto does have its own moon, there are other planets of similar mass nearby. For instance, there are a series of other planet-like objects orbiting in the outer edge of solar system (Eres, Ceres, Makemake for example). This suggests that Pluto does not meet the third IAU criteria, meaning it cannot expel neighboring dwarf planets/objects."

"I think size should matter to determiner weather something is a planet or not and Pluto has gotten to small I think to be called a planet."

"I honestly don't know enough to know how to answer."

"Pluto doesn't fall under the category of being a terrestrial planet nor a Jovian planet, therefore it is it's own identity which is considered a dwarf planet."

"Pluto should be a planet for several reasons. First of all it has a large enough gravitational pull to be described as a planet. Second of all, just because it does not fit into the categories of jovian or terrestrial does not mean that it is not a planet, it is a different type of planet. Third of all, Pluto is super cool and it is messed up that we gave Pluto the title of planet and then revoked the title."

"If Pluto doesn't fit all the IAU rules and classes then it shouldn't be called a planet."

"The IAU has been studying these things for some time. If we don't stick to some kind of set rules for naming things, we'll have too many planets."

"I'm not too invested into whether or not Pluto should be a planet."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Can you further explain what happened to Mars' water, because I am still confused."

"Something I found confusing is that on Mars water would immediately boil into vapor, but there are polar caps that are frozen? That confuses me because wouldn't the polar caps just vaporize, too?" (Liquid water would immediately boil into vapor, but solid chunks of ice could survive, especially underground (permafrost), or at the much colder polar caps (which are so cold that carbon dioxide snows as dry ice.)

"Have you ever watched the show Psych? One of the main character's pick up line was, 'You heard about Pluto? That's messed up, right?'"

"I have read that Pluto is a part of the Kuiper belt, is that true?" (Yes, Pluto is just one of an estimated 100,000 other comparable-sized dwarf planets in the Kuiper Belt.)

"Is Pluto a planet or not?"

"Do you think Pluto should be a planet?" (Eh, no. Otherwise then everybody else in the Kuiper belt would get to be planets, too.)

"Would you ever purchase a star and name it after something? (Like your wife lol.)" (No, because I think that company is honestly pretty shady, and not really the "official" registry for star names, as well.)

"Why does Haumea look like an egg?" (It is hypothesized that its rapid rotation rate stretched and distorted its shape as it solidified.)

"This lesson seems easy at first but kinda have to remember a lot."

"Are we going to eventually learn the math for what we have learned/are learning?"

"There are some claims that were made about NASA not actually making it to the moon, are these some things we can consider or that it's just conspiracy theory?" (Buzz Aldrin, the second person to set foot on the moon, was so annoyed by a conspiracy theorist pestering him to admit the moon landings were fake that he punched him in the face. #justsaying)

Online reading assignment: diffraction

Physics 205B, spring semester 2020
Cuesta College, San Luis Obispo, CA

Students have a bi-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 diffraction.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"I understand that when you decrease the size of W, then the theta or spread increases, and visa versa, increasing W would lead to a more narrow spread, which helps with telescopes. I also understand how waves can bend around the edges of the slit, not just shining directly through."

"Diffraction is the bending of light waves around obstacles or edges of an opening. As light moves through a slit, it will result in an angle that will vary depending on the size of the opening. As the W (width) of the slit increases in size, the angle of light expelled decreases. As W decreases, the angle will increase."

"Diffraction is the bending of waves around obstacles. I also understand that the degree of bending in light is much less than in sound."

"The diffraction minima is given by W·sinθ = m·λ where W is the width of a single slit, θ is the angle of the spread from the center, and λ is wavelength of light."

"Diffraction is how light is perceived and bends through a slit. What is important is how large the wave length is and what the angle it is exiting from the slit at compared to the 'normal.' As the slit increase, the minima angle decreases and vice versa. When talking about telescopes, they use a large width so the angle must be small to resolve details of far-away objects."

"Essentially, decreasing slit width W causes an increase in the 'spread' of the half-angle θ. Conversely, increasing slit width would produce the opposite effect onto the spread of θ."

"The slit width and analogies were perfect. The example in the ocean with the waves is both a pun and a great example! "

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"The dark fringes for single-slit diffraction was confusing to me."

"I guess I didn't really understand what a slit is."

"I am confused about how to find the minima angle. I am also unsure of where it comes in and if it is only with destructive interference."

"I was confused about the midpoint of a central bright fringe. I did not understand what that had to do with the destructive interference. "

"What is the difference between spread angle and diffraction minima?"

"I am slightly confused as to what effects the relationship of slit width and spread of theta cause. Looking at the telescope example, I believe I understand the idea that a larger slit with produces a smaller theta causing less spread and a more refined image."

"I'm not understanding the diffraction of light through the telescope, and the hair laser example."

"Not much really. A few examples and minor explanation should get me up to speed."

"I didn't find anything confusing about this topic. "

"Honestly just haven't got to this yet."

Match the single slit parameter with its symbol. (Only correct responses shown.)

Width of a single slit: W [94%]
Wavelength of light passing through the slit: λ [97%]
Direction, as measured from the centerline: θ [97%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"May you explain the textbook diagrams in class? The textbook's diagrams and graphs made the concept more difficult."

"Light without diffraction would pass straight through a narrow slit without spreading out?"

"By making the slit width larger and larger does there reach a point where making the slit larger would result in an inconsequential reduction in the spread of the diffracted waves?" (Yes. If the slit were large, then diffraction (the "wrapping around the edge effect") would be less noticeable, and the light would not seem to spread out much, so the beam would have the same size/shape as the slit. If the slit were very small, then the "edge effect" would be more noticeable, and the light will spread out more such that the beam would "fan out.")

"What is the m referring to in the equation sinθ=m·λ/W), as explained by the textbook? Will there ever be a time when m will be more than 1?" (Yes, in order to find the fainter dark fringes off to the side of the "spread angle" (where m = 1), but we'll only concentrate on the light contained within the m = 1 "spread angle," because that's where most of the spread-out light is concentrated after passing through the slit.)

"I was curious as to what happens when two slits are close to each other. Can they have constructive interference?" (Yes, provide that each slit is small enough that light will spread out (diffract) so they will overlap with each other, and then can interfere with each other.)

"I am glad you're my professor. My other class I felt so lost the whole time but this semester I don't."

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

Astronomy 210, spring semester 2020
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.

"I found Earth's active crust very interesting. I found this interesting to try to picture the surface of Earth just floating on the mantle."

"'Runaway greenhouse.' I thought this concept was interesting because I found the greenhouse effect interesting to begin with, but to find out that this is the reason why Venus lost its oceans and habitable atmosphere."

"That Venus could have possibly had oceans like Earth."

"The fact that Venus could have been like Earth. A long time ago it was close to how Earth is weatherwise but then with all the volcanoes exploding and putting CO₂ into the air, it started rapidly being a runaway effect and now is the planet as we know it. I just think it's interesting how in the future something like this could happen to Earth if we let it get that bad."

"Venus' atmosphere is *96%* CO₂--that's insane, I knew it was primarily greenhouse gases but I didn't know it was that much CO₂."

"I found it interesting that we only have a few pictures of the surface of Venus. This interests me because I am attracted to the magic in the universe, and I find that for me, the most magical things are the ones we don't know."

"The maps of Venus and Mars were interesting because it showed basically what their surfaces were and what they're made of."

"The atmosphere of Mars is thinner than Earth's. It is 1% as dense as Earth."

"I found it interesting how Mars has little water, but it is composed of frozen ice water that is covered with carbon dioxide."

"That no liquid water can be present on Mars to this day due to the low atmospheric pressure."

"Mars has small moons, which Mercury and Venus don't. The moons are captured asteroids. I knew Mars had moons but, I didn't know those moons where captured asteroids."

"The term 'jovian planets.' "

"I found gas giants to be the most interesting. Just because it's cool to see different compositions of planets."

"I thought that reading about Jupiter's interior and its atmosphere. I had no idea that Jupiter is only 1.3 times denser than water, which is super interesting and something I had no idea about. Learning that liquid metallic hydrogen makes up Jupiter's interior was a fun fact. Jupiter's force is 10 times stronger than Earth’s force which I usually just learned about Earth and its interior so it's interesting to learn more about other planet and how different it is from Earth."

"What I found the most interesting about the readings were the jovian planets and the dwarf planet Pluto. I found this interesting because I feel that we know more about the inner and terrestrial planets because since they are closer to Earth, they are easier to study and easier to observe. Since Jovian planets are further away, they may be more difficult to study and observe, and we may not know as much about them and their properties. They seem more foreign, which makes them more interesting."

"The difference between a planet and a dwarf planet. It all depends on their size."

"The reasons Pluto isn't a planet anymore. When I was young, I thought it was about size, not gravitational force."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"The greenhouse effect is still a little bit confusing to me, I understand the basics, but could use a small review."

"Remember what planet is which and its characteristics are confusing."

"Did Venus' greenhouse cycle collapse relatively recently or was it millions of years ago, and how long is it estimated to have taken for its oceans to have evaporated? That's what I don't understand, do we just not have any idea since it's so hard to get a probe there and keep it working."

"The runaway greenhouse effect on Venus wasn't very detailed and I need further information to understand."

"How/where did the preexisting water on Mars go?"

"Shield volcanos. I just don't understand how they are formed."

"How the jovian planets gained so much mass in the first place. I believe it had to do with how much gas was around when it formed and gravity took over the rest but I'm not sure."

"Jovian planets. Just completely lost."

"Which is the coldest jovian planet. I could not find where it told us."

"I didn't quite understand the reasoning for why Uranus cooled faster than Neptune and what it’s axis has to do with it. I understand the Cooper Cooler® effect but don't quite understand how it applies to Uranus."

"How can a planet even get rings?"

"Something that I still don't understand fully is why the IAU considered Pluto not a planet in the solar system."

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 [64%]
Volcanic outgassing, up until now: about the same as Earth [36%]
Heat from the sun: more than Earth [82%]
Amount of atmosphere, today: more than Earth [61%]

Identify the relative amounts of these characteristics for Mars, compared to Earth. (Only correct responses shown.)

Interior core heat, today: less than Earth [61%]
Geologic activity, today: less than Earth [86%]
Volcanic outgassing, up until now: less than Earth [43%]
Heat from the sun: less than Earth [64%]
Amount of atmosphere, today: less than Earth [82%]

Which jovian planet has the coolest interior temperatures?

Jupiter (most massive).	[0]
Saturn (most prominent rings).	** [2]
Uranus (least active weather patterns).	********** [10]
Neptune (farthest from the sun).	************* [13]
(Unsure/guessing/lost/help!)	*** [3]

I believe Pluto should be a planet.

Strongly disagree.	*** [3]
Disagree.	******* [7]
Neutral.	********** [10]
Agree.	***** [5]
Strongly Agree.	*** [3]

Briefly explain your answer to the previous question (whether Pluto should be a planet).

"Pluto should be considered a planet because it had be considered a planet before why not know."

"I disagree that Pluto should be a planet because: it doesn't meet the IAU's criteria for for planet status, and planetology shows that Pluto isn't related to jovian nor terrestrial planets."

"Why would they make it a planet and then just say, 'Hey let's not consider Pluto a planet anymore?'"

"The status of Pluto shouldn't matter but rather what information we can learn from it."

"It's still pretty big, doesn't orbit another planet, and it has moons."

"I believe it should be a planet because its orbit is severe? wasn't able to read to this section The dwarf planet and others like it are not big enough to clear their orbital path."

"I feel that even though Pluto may not be big enough to be a planet it should still be classified as one since I mean it does have five moons."

"Because Pluto is in our solar system, it rotates and revolves. Plus it would be a little awkward explaining to someone saying, yeah that planet is in our solar system but we just ignore it. Give it the benefits of being a hard working planet even if it is small and slow."

"In the book one of the reasons Pluto is not a planet is because it's not large enough to dominate and gravitationally clear its orbital region."

"By the same classification, the the moon and Mars are both dwarf planets."

"Pluto is not related to the jovian planets or terrestrial planets and is isn't really special in a way. I do not believe that Pluto should be a planet."

"I am not really sure if it should be a planet or not. Because what are the characteristics to define a planet. if we decided to call a planet at one point why did we go back on it?"

"I grew up thinking Pluto was a planet."

"I never really was educated on why Pluto wasn’t a planet anymore, I was just told, but when the book mentioned that it is jovian and other reasons then it makes sense. However at the same time, they made Pluto a planet originally which means they would have evidence which would justify it. This is why I don't really have an opinion."

"I believe Pluto should be considered as a planet because just like any other planet it has an orbit around the sun and even gets closer to the sun in orbit than Neptune at times. Also like a planet Pluto has moons that orbits itself like any other planet would have as a charchteristic."

"I believe it shouldn't because its too small and too far out of our solar system the convention that produced the definition excluding pluto as a planet had a small attendance and their definition that excludes Pluto from being a regular planet, that being it hasn't 'cleared its neighborhood,' excludes Earth, Mars, Jupiter, and Neptune as they share their orbits with asteroids. less than 5% of the astronomical community voted for the change, which hardly represents the total opinion."

"I think if NASA has one stated that it's too small to be considered and it can not make its own orbital path clear then we can't call it a planet like the others."

"If I am correct I think I remember hearing many disputes about whether or not Pluto should be considered a planet but I think it is a dwarf planet. I put neutral due to not knowing the reasons for why it should or should not be a planet."

"Scientists have made Pluto no longer a planet and I trust their judgment."

"From my point of view, I decided that Pluto shouldn't be planet because Pluto is just a chunk of ice floating around the Kuiper belt."

"I picked neutral on whether if Pluto should or shouldn't be a planet because I don't think that I know enough about Pluto to say yes or no."

"With the information I have, I'm neutral because it sounds like it has an orbit since it has 5 moons, but at the same time I'm wondering if the moons are just in the same orbit Pluto is trapped and not actually trapped in Pluto's individual orbit."

"I am not quite sure of Pluto should be or should not be considered a planet, but I may lean towards that it isn't a planet, since it is not classified as terrestrial or jovian and it does not have the normal properties of a planet."

"A planet must be large enough to have the largest gravity in its own vicinity, and Pluto doesn't."

"Pluto is really close to a lot of other dwarf planets."

"This statement is not something I can answer. Pluto is a planet. A dwarf planet. So whether I believe it should be or not is irrelevant."

"Pluto has moons so it should be considered a planet."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Venus and Mars are so different, why? Is it just due to the different distances from the sun?" (Also their size as well.)

"Can you go over the planets and what considers something to be a planet?"

"Do you believe that Pluto deserves the recognition to be considered as a planet?" (Eh, not really. There are lots of other planets that were historically demoted as well, notably Ceres.)

"What would the modern reaction be if another planet was classified as no longer a planet or if one that wasn't previously was made into a planet?"

"I think I need a tutor for astronomy because the concepts just don't click with me." (There is an astronomy tutor available on SLO campus on Mondays and Wednesdays.)

Online reading assignment: interference

Physics 205B, spring semester 2020
Cuesta College, San Luis Obispo, CA

Students have a bi-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 interference.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"I understand that if two sound speakers are wired the same, then they will be in phase which results in constructive interference and the sound will be louder. If they are not wired the same, then they will be out of phase which results in destructive interference and a more quiet sound."

"If two waves are in phase and have a whole length difference, they will produce constructive interference. If the waves are out of phase or have a half wavelength difference, destructive interference is produced."

"The principle of linear superposition states that the resultant disturbance is the sum of the disturbances from the individual waves. I also understand that interference alters the brightness of light and loudness of sound."

"This paragraph from the presentation helped me understand the basics: 'Here we have two speakers, which are our sources of two sound waves. Since they are plugged into the same frequency source, they will generate sound waves of the same frequency f (which is depends only on the source), same speed v (which depends only on the medium), and thus the same wavelength λ (which depends on both f and v). If the speakers are wired the same way--red and black wires to red and black plugs--then they will oscillate in phase, with both speaker cones moving forward and backwards in unison.'"

"I understood the in-phase and out-of-phase part, and how to tell the difference. I also understood what is constructive and destructive."

"The way two wave sources are emitted determines whether the resulting wave will be constructive or deconstructive. In-phase waves have the same velocity, wavelength, and frequency, also in-phase waves are traveling in the same direction and can form a constructive of bigger resulting wave. Out-Phase waves do not align crest to trough and they do not have the same velocity, frequency or wavelength and the resulting wave is smaller or no wave."

"My primary take-away from this set of slides is the difference between constructive interference (music playing from the neighbor's stereo), and destructive interference (silence, or quieted volume). When the crests and troughs of the two wavelengths line up, constructive interference occurs; however, if those wavelengths are not aligned, destructive interference takes place."

"There was not much that I understood from this presentation."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"I need a little more detail about when the interfering wave examples have a whole wavelength path length difference or half-wavelength path length difference."

"Completely grasping the constructive/destructive conditions flowchart."

"I found the flowchart of constructive/destructive conditions to be overwhelming especially because I don't fully understand the solid lines vs. the dashed lines. I could also use a bit of clarification on what path difference is."

"I would like a little more understand on phase differences. As well as how path length difference works."

"At first, the path length difference was confusing to understand because I did not comprehend the equations. However, after seeing some visual examples, I now understand and can observe whether a wave will be constructive or destructive."

"The difference between constructive and destructive seemed confusing. Its relationship with waves was easier to understand with the diagrams."

"I found a lot confusing with these concepts. I don't understand the difference between constructive and destructive waves. I also don't how changing the distance makes the two so different. I am also confused what they are considered when the waves are in unison, but the distance is changed."

"How does this work for radio waves? Please give examples of constructive, destructive and non-coherent sources. The book only uses visible light as an example."

"This isn't very confusing to me."

Classify the various interfering wave examples. (Only correct responses shown.)

1: in phase sources [91%]; whole wavelength path difference [74%]; constructive [97%]
2: in phase sources [14%]; half wavelength path difference [86%]; destructive [89%]
3: in phase sources [86%]; whole wavelength path difference [77%]; constructive [89%]
4: out of phase sources [86%]; whole wavelength path difference [40%]; destructive [94%]
5: out of phase sources [23%]; half wavelength path difference [49%]; constructive [86%]
6: out of phase sources [89%]; whole wavelength path difference [54%]; destructive [97%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Finally lenses are over. I don't wear glasses so it was a difficult set of chapters." (I'm not so sure that this topic was any easier for student who do wear corrective optics.)

"When you change the volume on a stereo how is more sound produced? Are more sound waves generated?" (Well, "more" in the sense that the speaker cone moves in and out with a larger range of motion (larger amplitude), so more air is pushed in and out, and a greater range of pressure fluctuations result.)
"What does m stand for in the constructive/destructive conditions equation?" (Any whole positive/negative number (0, ±1, ±2, etc.).)

"Why in the world could I not find anything about path length differences?"

"May we review situation #5 specifically?"

"I just need a brief discussion about these ideas and I think I will be good on this topic."

"The wave interference problems don't seem too difficult, just need some practice."

"In that case given the two sources had the same total length and each crest and trough matched, I assumed there would be no length difference; yet, that was not an option?" (A case where there is no path length difference is the covered under the case of having a path length difference of a whole (number) of wavelengths, in this case the whole number would be zero.)

"If two sound waves are not exactly a half-wavelength off from each other, would there still be destructive interference?" (Yes, but they would not completely cancel each other out. The resulting loudness would be quieter than a single wave, but not completely quiet.)

"Will we be using noise-canceling headphones?" (That is a great application of destructive interference, but no. You can always purchase a set for yourself, though.)

"I was confused about coherent and non-coherent light sources of light. What makes a laser coherent compared to light bulbs which are incoherent?" (Basically, the light from a laser has a constant amplitude, single wavelength that starts off with a definite phase, while light from an incandescent bulb is a range of different wavelengths that can vary in amplitude and phase. It's a bit more complicated than that, but for our purposes we'll start from this working definition.)

Astronomy current events question: Betelgeuse dimming

Astronomy 210L, spring semester 2020
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!)

Bob King, "Betelgeuse is Dimming...Why?" (December 31, 2019)
skyandtelescope.com/observing/fainting-betelgeuse/

The red supergiant Betelgeuse in the constellation Orion is currently at a "superminimum" brightness as it:
(A) collapses into a black hole.
(B) depletes its heavy elements.
(C) points its axis away from Earth.
(D) passes behind its binary companion.
(E) expands and contracts its atmosphere.

Correct answer: (E)

Student responses
Sections 30679, 30680
(A) : 7 students
(B) : 4 students
(C) : 1 student
(D) : 0 students
(E) : 23 students

Astronomy current events question: oxygen extraction from lunar material?

Astronomy 210L, spring semester 2020
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!)

News release, "ESA Opens Oxygen Plant--Making Air Out of Moondust" (January 17, 2020)
esa.int/Enabling_Support/Space_Engineering_Technology/ESA_opens_oxygen_plant_making_air_out_of_moondust

The European Space Agency demonstrated that a molten salt electrolysis process could extract __________ from material on the moon.
(A) gold.
(B) oxygen.
(C) helium-3.
(D) salt water.
(E) amino acids.

Correct answer: (B)

Student responses
Sections 30679, 30680
(A) : 0 students
(B) : 31 students
(C) : 1 student
(D) : 1 student
(E) : 2 students

Astronomy current events question: planet formation around red dwarfs

Astronomy 210L, spring semester 2020
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!)

Rachel Atkinson, "UCLan Astronomers Find a Way to Form 'Fast and Furious' Planets Around Tiny Stars" (January 21, 2020)
uclan.ac.uk/news/uclan-astronomers-find-way-to-form-planets-around-tiny-stars.php

Researchers propose that giant planets can rapidly form around red dwarf stars, based on:
(A) solar flare activity.
(B) gravitational waves.
(C) computer simulations.
(D) interstellar dust samples.
(E) planetary ring compositions.

Correct answer: (C)

Student responses
Sections 30679, 30680
(A) : 2 students
(B) : 4 students
(C) : 15 students
(D) : 7 students
(E) : 6 students

Astronomy quiz question: morning star Venus?

Astronomy 210 Quiz 2, spring semester 2020
Cuesta College, San Luis Obispo, CA

The locations of Mercury, Venus, and Earth are shown in the diagram below (not to scale, and orbits have been simplified as circles instead of ellipses).


At sunrise, Venus will be:
(A) low over the east horizon.
(B) somewhere high up in the sky.
(C) low over the west horizon.
(D) not visible in the sky.

Correct answer (highlight to unhide): (A)

If a line is drawn from Earth to the sun, the observer at sunrise (6 AM) is located perpendicular to that line.


Everything above that line would be above the horizon, such that Venus will be visible at sunrise, low over the east horizon.

Section 30676
Exam code: quiz02SnRl
(A) : 20 students
(B) : 2 students
(C) : 8 students
(D) : 14 students

Success level: 48% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60

Astronomy quiz archive: eclipses/history of astronomy

Astronomy 210 Quiz 2, spring semester 2020
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz02n1xI


Section 30674

0- 8.0 :	** [low = 6.0]
8.5-16.0 :	*****
16.5-24.0 :	******* [mean = 23.8 +/- 9.0]
24.5-32.0 :	*********
32.5-40.0 :	******* [high = 36.5]

Section 30676, version 1
Exam code: quiz02SnRl


Section 30676

0- 8.0 :	** [low = 8.0]
8.5-16.0 :	*******
16.5-24.0 :	*************
24.5-32.0 :	********* [mean = 24.8 +/- 9.2]
32.5-40.0 :	************* [high = 40.0]

Astronomy quiz question: evening star Venus?

Astronomy 210 Quiz 2, spring semester 2020
Cuesta College, San Luis Obispo, CA

The locations of Mercury, Venus, and Earth are shown in the diagram below (not to scale, and orbits have been simplified as circles instead of ellipses).


At sunset, Venus will be:
(A) low over the east horizon.
(B) somewhere high up in the sky.
(C) low over the west horizon.
(D) not visible in the sky.

Correct answer (highlight to unhide): (D)

If a line is drawn from Earth to the sun, the observer at sunset (6 PM) is located perpendicular to that line.


Everything below that line would be below the horizon, such that Venus will not be visible at sunset.

Section 30674
Exam code: quiz02n1xI
(A) : 5 students
(B) : 3 students
(C) : 5 students
(D) : 18 students

Success level: 59% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.88

Online reading assignment: atmosphere problems, Earth, the moon, Mercury (SLO campus)

Astronomy 210, spring semester 2020
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 problems caused by the atmosphere for telescope observing, Earth, and the impacted worlds: the moon, and Mercury.

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.

"That light waves can be affected by our atmosphere. I just found it interesting because it was something that I never considered."

"How light pollution can affect so many things in our environment, such as animals."

"That light pollution interferes with the view of the stars/planets. People would then need go to hilltops far away away from the light pollution just to look at the clear stars and planets."

"I found light pollution very interesting and did not think it was a very big problem until I read into it some more."

"Something I found interesting was that if you were to go to a rural town with not very many lights you could see a faint Milky Way. I found that interesting because we do not get that many chances to see it if you do not leave your hometown."

"Comparing the atmosphere to rippling water was a good analogy. I found this part interesting because I knew that the atmosphere made it more difficult to view view things using a telescope, but this comparison made it easier to understand why."

"I found the comparison between sitting under a pool of water and looking up to sitting under a 'pool' of air really interesting. I never thought about how movement in the sky, such as turbulence, could create such a problem for astronomers or anyone interested in the views of the sky."

"I found learning about how atmospheric turbulence and opacity affect our ability to use telescopes and the ways we combat those effects interesting. I never understood why it was better to have telescopes at a higher altitude and now I do."

"I found the readings about different ways that astronomers have to go about collecting different types of electromagnetic radiation. I found this interesting because it forces them to find new and interesting ways to collect data, which leads to a deeper understanding of our known universe."

"I thought that it was very interesting that telescopes in space can be the size of a bus. This is crazy to me how they can be that and still be be able to function in space."

"Airborne and space telescopes (airplanes, balloons, rockets and satellites), because it is such an interesting perspective to think about."

"I liked reading about all the different atmospheres on the different planets and I liked how it got into global warming. I was also interested by the stages that earth has gone through to and how we'll basically always be in stage three because Earth's surface is constantly changing."

"The greenhouse effect of how an atmosphere traps heat and raises the temperature of a planetary surface. It's crazy how the atmosphere has such an effect on planets--without it, Earth would be a lot different."

"The large impact hypothesis, stating the bulk of two objects will combine to form Earth (and the moon), with most of their cores and the surrounding crust melting, then coalescing."

"I was interested particularly in the geology comparing the planet Mercury to our own moon. Both involved the formation of craters followed by partial filling of lava. I found it fascinating that both bodies were strikingly similar and figured that this could help us learn more about the formation of other planets."

"When learning about the history of Earth's moon, I really enjoyed reading about the magma ocean, it just sounds super awesome to picture."

"I thought the different sizes of the moon's core versus Mercury's core was interesting because you would expect them to remotely similar but are different and you can determine this by the gravitational pull."

"I really liked looking at the pictures of the moon's and Mercury's surfaces. It is cool looking at the ridges and craters shown in the pictures."

"I think it's increasingly interesting how much we think we know about other planets that is primarily based on extrapolation. All of this could change as soon as new evidence presents itself."

"Super-hectic weekend and wasn't able to get to the reading but I will before class!"

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"I do not understand the electromagnetic spectrum graph or how to use it."

"I did not quite get what the difference between radio astronomy and light astronomy was. I wanted to know, but was just lost by the name drop."

"I don't understand how atmospheric turbulence occurs."

"I'm still catching up on the history stuff, I'm really bad at remembering names and related numbers and just putting it all together in the right way."

"The greenhouse effect."

"How carbon dioxide enters and leaves the atmosphere and everything about it, mainly confusing because I thought I already had an idea and now I am jumbled up."

"I was confused about how an asteroid wouldn't be able to break the moon's structure or crack it, it would only leave a crater."

"Something I found confusing was trying to determine which craters were oldest to youngest. Personally because when I was reading the information I just could not retain it."

"That the four inner planets were composed of rock when the outer planets are not."

"The atmosphere on Venus. Why is it so cloudy and thicker than Earth's? It's confusing for me because I thought all the planets had the same amount of atmosphere."

A large modern optical telescope in outer space would have images with better __________ than a comparable ground-based telescope.

brightness.	******** [8]
resolution.	************************ [24]
magnification.	* [1]
(Unsure/guessing/lost/help!)	*** [3]

Stars to appear to "twinkle" in the night sky because of...

"The stars twinkle in the night sky because of the effects of our atmosphere. When starlight enters our atmosphere it is affected by winds in the atmosphere and by areas with different temperatures and densities. This causes the light from the star to twinkle when seen from the ground."

"Movement within the atmosphere causing the images of the stars to move and blur."

"Stars appear to twinkle in the night sky because of the effects of our atmosphere. When the light from the stars enter our atmosphere, it experiences turbulence. This causes the stars to look like they 'twinkle.'"

"Living in at the bottom of an 'ocean of air,' turbulence disturbs the air in the atmosphere, making our view disrupted."

"The way our atmosphere moves and shakes."

"I'm not sure, I don't remember this part of the reading."

"Unsure."

Identify how carbon dioxide enters and how it is taken out of Earth's atmosphere.
(Only correct responses shown.)

Enters atmosphere from: volcanoes [44%]
Taken out of atmosphere by: oceans [57%]

Identify the oldest (longest ago) to the youngest (most recent) features on the moon.
(Only correct responses shown.)

Craters partially filled in with flat lava plains: oldest (formed longest ago) [31%]
Flat lava plains: middle [22%]
Craters on top of flat lava plains: youngest (formed most recently) [53%]

Identify the oldest (longest ago) to the youngest (most recent) features on Mercury.
(Only correct responses shown.)

Large crater basins: oldest (formed longest ago) [39%]
Lava-filled lowlands: middle [61%]
Long curving ridges: youngest (formed most recently) [58%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I was unsure about why the segmented mirrors might be beneficial. The textbook said that the thin mirrors weigh less and cool faster?" (Yes, saving weight is important when there are so many mirror segments in a large telescope, and having the mirrors be able to cool down (or warm up) quickly is good, because any temperature differences will make a "mirage" effect from thermal air currents around the mirror segments.)

"I found understanding the order that the features formed on the moon and mercury difficult to grasp, the moon a little more so than Mercury. To me, neither the textbook or online presentations presented a clear order and explanation of how we can tell which order they came in."

"I was confused about the order that things occurred on moon because I searched pretty hard and couldn't really find the definitive answer." (We'll be sure to cover this in class this week.)

"What is the significance of knowing the surface features of the moon? Those are just the way it formed, but I would want to know why it's so important to study the moon." (We brought back an abundance of samples from different parts of the moon for thorough laboratory analysis, so we have a very good idea of how the moon formed. Since we do not have samples from other planets (yet) that we can analyze back here on Earth, then the best way to understand those outer planets is to compare their similar/different features compared to the moon's features.)

"I thought the large impact theory in reference to the moon and Earth colliding would have ruined the round structure of both, but I assume over time the gravitational pull at the core would reshape the round sphere?" (Yes, the impact would melt/vaporize both, but as that material cooled gravity would bring everything back together similar to how they first formed by themselves, but now they'll form side-by-side, with the current moon made mostly of the vaporized outer layers of both.)

"I don't totally understand how the large impact theory for the moon's formation is supported when there's contradictory evidence." (Well, it is the best supported and also least contradicted theory given the evidence available.)