final

From the reading "Cargo Cult Science," how would you explain to the "cargo cult" people of the South Seas why the planes don't land? Answer in a simple, direct way: what are they doing wrong, or why is what they are doing not working? Hint: think about why the planes REALLY landed and what has changed.

* looking at the bigger picture
* understand every aspect of the situation
* there was a war bringing in the landing planes which the cargo cult did not understand because they were disconnected from the outside world in a way.

From the reading "Philosophy and the Scientific Method," (a) explain one of the benefits of irrefutable ideas and also (b) explain the major weakness of a system of knowledge based upon irrefutable ideas.

a) belief cant be tested and give certainty. there is a finality to our views and it can always be viewed as a plan. it makes us feel good even if its just a “maybe” belief

b)ignorance, if it cannot be proven true, it must be false. you cant come to a consensus so conflict arises because everyone thinks their beliefs are right.

From the article "The Physical Science Behind Climate Change," explain the evidence found in computer models of the climate that indicate that natural climate forcings are not sufficient to explain the rise in average temperature since the mid-20th century and that anthropogenic (human-caused) factors must be largely responsible.

* one model can take data from months/days ago to predict the future years only using natural forcings
* another model can do the same and factor in human intervention like greenhouse gases


* comparing both model predictions to the next years real data, the data that correlates the most to the real numbers is the one that factored in human intervention, showing humans are responsible for extreme climate change.

From the article "The Physical Science Behind Climate Change," explain two patterns in our atmosphere that the authors consider to be a fingerprint of human influence, showing humans are caused the changes and not natural sources (like changes in solar activity).

1- greater warming @ surface of the ocean than in its deep layers which is consistent with the greenhouse gases warming in our atmosphere → surface is the first to touch the atmopshere so it gets hotter faster than the deep ocean water would

2- troposphere has warmed while the stratosphere has cooled; if this were due to solar changes that would mean both layers would be warm but they’re not so thats how we know its a human interference

From the article "The Last Great Global Warming," after an initial buildup of Carbon Dioxide in the atmosphere caused perhaps by volcanic eruptions 56 million years ago, describe three other changes that occured (likely due to the initial Carbon buildup) to add even more heat-trapping gases to the atmosphere in a geologically short time (thousands of years).

1- thawing permafrost that burps up methane

2- drought exposes forest and wildfires that come from that release CO2

3- deforestation changes the rain patterns so forest die off

From the article "The Last Great Global Warming," describe the two chemical changes that occured in the oceans due to the buildup of CO2 in the atmosphere.

1- acidification: surplus amount of carbonic acid

2- oxygen content dwindling: warm water cannot hold as much life as cold water can

From the article "The Last Great Global Warming," how do we know the temperature of the water at the time these ancient sediment deposits occured? 

mix of different forms / isotopes of oxygen atoms in skeletal remains revealed the temperature of the water

From the Scientific American article "The Permafrost Prediction," if the permafrost in a given region thaws, (a) not all of its Carbon will be released and (b) what is released will be released slowly over decades or centuries. Explain each of these two claims (the first two of three key questions posed about Carbon release in the article).

a) not all carbon is released: warming ground with snow → plants have longer growing session to decompose nutrients into the soil → it thaws → plant absorbs it and CO2

b) in the summer, extra plant growth is pushed inter-shift and excess Carbon goes into atmosphere

From the Scientific American article "The Permafrost Prediction," if the permafrost in a given region thaws, some Carbon will be released from the soil, but it is also true that the same region will absorb more Carbon from the atmosphere. (a) Explain why, and (b) explain whether the net result is more Carbon added to the atmosphere or more absorbed from the atmosphere.

a) carbon is absorbed because the plants in the surroundings take in CO2 and sort of lock it so when an area thaws, the soil is prone to absorbing CO2 for plant growth

b) the next result puts more CO2 in the atmosphere, not a balance

From the Scientific American article "Meltdown," we learn that when “permanent” ice melts (either on the ocean or on land) due to warming, feedback effects from this can cause even more warming. Explain three ways the melting ice causes further warming in the Arctic.

1- sea ice in ocean recedes, heat and moisture can warm the air, furthering the slow formation of ice

2- permafrost thawing so buildings on top of it collapse and thawing soil releases heat-trapping gasses into atmosphere

3- frozen water on land like glaciers and icecapades will create runoff into the ocean and raise sea levels

From the "Flat Earth" video, in one popular variant of the Flat Earth theory, our apparent weight is not caused by gravity but rather a constant upward acceleration of the flat disk of the Earth. Describe an observational fact that refutes this model.

it would disprove the orbits of moon and sun that are calculated from gravitational law

From the decoding weather video, explain how Dr. Andrea Dutton is able to reconstruct the history of temperature in the Earth’s atmosphere over the past 800,000 years (explain how is oxygen used in the process).

she analyzes the chemistry of the shells to find the temperature of the water at the time the shells developed and find how much oxygen was in the water at that time

From the decoding weather video, we find there is an imbalance in carbon.  When we calculate how much carbon we are emitting, only about half of it shows up in the atmosphere, so we want to know where the rest of the carbon goes.  Explain (a) how Dr. Greg Asner is attempting to answer this question (what instrument does he use and what does he measure), and (b) explain about what fraction of emitted carbon is being accounted for with Asner's measurements.

a) he calculates how much CO2 we put in the air and measures it. half of what we emit isn’t staying in the atmopshere → means forests soak up CO2 into woods, leaves, roots, trees and carbon is held there → atmosphere cools by reducing heat trapping gases

b) trees absorb 25% of extra Carbon in atmosphere

From lecture, what is (a) the major benefit and (b) the major drawback of a system of knowledge based upon scientific principles?

a) common consensus among society

b) lead to ignorance

From lecture, (related to Q1.11 and Q1.12) use a graph of blackbody radiation to help explain why gases that block infrared light tend to warm the Earth due to the nature of the incoming and outgoing light (the blackbody curves).

warmer → melt permafrost → more co2 → cycle (organic decay)

From the Scientific American article "Gather the Wind," explain how electrolyzers work. Specifically, (a) describe how the energy is stored, and (b) describe how a fuel cell releases this stored energy for later use.

a) water split into H and O; H is stored, then let out a little and combined with O, it releases energy

b) fuel cells burn hydrogen efficiently. Storing hydrogen means gas must be liquefied or compressed

From your textbook's chapter 6.4, (a) explain why radio telescopes typically have much worse resolution than optical telescopes, and (b) briefly describe how interferometry can be used to overcome this problem.

a) the longer the wavelength of radiation, the harder it is to resolve fine detail in the images or makes because the wavelength distorts and blurs images 

b) combining telescopes increases the effective aperture (diameter) and helps clear images 

From your textbook’s chapter 7.3, (a) describe how we estimate how old a planetary surface is (how long since it has undergone a major change). Also, (b) describe how we determine the age of a rock (how long ago it solidified).  Specifically for (b), what three things do we have to know in order to estimate the solidification age of a rock?

a) counting the number of impact craters 

b) 1- half life (how long it takes to decay), 2- how much radioactive parent was there, 3- how much radioactive daughter was there 

From your textbook's chapter 14.2, although iron-type meteorites account for only about 3% of meteorites that fall to the Earth, about 42% of meteorites that have been found on Earth are iron meteorites.  Explain why this is true.

Pure iron almost never occurs naturally on earth so iron that we have is either manmade or from a meteorite.

From the Scientific American article “What Is a Planet?” - In the year 1851, the number of planets had grown to 15. What were all of these extra planets and why were they eventually disqualified from planet status? 

* extra planets were asteroids thought to be small planets orbiting the sun.
* people didn’t want to be naming so many planets, so they classified them as asteroids together in a belt
* not considered planets because they were close in proximity to each other and not all of them were round

From the Scientific American article “Secrets of Primitive Meteorites” - The author asserts that carbonaceous chondrites probably orbit furthest from the Sun compared to any other type of chondrite. Explain why the author thinks this is true

Are known to have a lot of organic compound within them which is not sustained when near high temperatures.

From the Scientific American article "Secrets of Primitive Meteorites" -- Explain why the author concludes that our early solar system probably resembled the dusty disks surrounding a class of young stars known as T Tour stars.

solar-nebula dust map = Dusk patterns resemble it due to its distribution and amount matches the dust forming around new stars

From the Scientific American article "The Seven Year Mission," describe two reasons why the target for the OSIRIS-Rex mission was the asteroid Bennu. 

1- collect samples from bennu bc it has a lot of organic compounds related to help us learn more about life
2- bennu's orbit brings it close to earth so it can be considered hazardous bc it could potentially hit us

From the video on climate science, explain how perovskites may fundamentally change the way we harvest solar energy, how it differs from using silicon.

* takes energy from sun→ electricity
* takes just a few strokes of its paint on solar panel to generate power

From the video on climate science, explain how Dave Montgomery and Anne Bickle’s research into farming/gardening techniques may help reduce the overall amount of carbon in the atmosphere if adopted on a broad scale (talk about the example of Dave Legvold’s farm).

* mimicked nature to speed up its natural process
* adding a plant enhancer to soil
* soil takes in carbon → sugar → release it to its roots for nutrients
* when plant dies, its decay brings nutrients to soil and reduce carbon in atmosphere because the soil takes it in and uses it for its own type of energy.

From the video "Can We Cool the Planet," several scientists in the video discuss their efforts to understand the effects of geoengineering (e.g. making clouds bright or releasing reflecting particles high the atmosphere).  Describe two potential drawbacks to this approach as a "solution" to human-caused climate change.

1. fossil fuel companies won’t think it is necessary to stop because they will think the problem is “fixed”

* an excuse for big fossil fuels to fight emissions cuts


2. Pumping aresols into atmosphere to make clouds brighter and reflect more sun so that it'll cool the earth

From the video "Chasing Pluto," describe the theory proposed in the video that explains why Pluto is so small.  Explain what interrupted its formation process.

* planets form when material starts to stick together
* pebbles turn into boulders, boulders into mountain-sized comets; comets turn into proto planets and into planets.
* maybe Pluto is remains of planet formation called planetesimals, celestial objects that somehow stopped growing.

From your textbook's chapter 21.4, explain how we deduce the approximate size (or radius) of transiting exoplanets. Also, how do we deduce the density of these exoplanets in order to determine whether they are rocky or gaseous?

* Size: bigger the planet, bigger eclipse of an exoplanet
* Mass = distance to star and compare it to its orbital period. The stronger the tension (slow orbit), the heavier the exoplanet is. Ex: swinging a lanyard vs swinging a bowling ball
* density = mass of planet / volume of the planet

From your textbook chapter 21.5, figure 21.23 is a bar chart showing the percentage of each category of planet size detected by the Kepler mission.  Figure 21.24 is a bar chart showing the ACTUAL percentage of each category of planet size in the galaxy.  Explain why these two bar charts are different (in other words, why are there more small-sized planets out there compared to what Kepler found).

when we correct our bias on how many planets there are (including the ones we can’t see or detect), it seems that there are a lot more small sized planets like earth.

From the Scientific American article “A Planet is Born,” what is the main weakness (or bias) in the two most popular exoplanet detection techniques (transit and radial velocity), and how do the observations of the ALMA telescopes enable us to spot solar systems more like our own?

* bias: exoplanets have to be both large and close enough to earth in order for us to be able to detect them. Thus, we only observe exoplanets that have a strong enough wobble to be detected
* ALMA uses patterns of dust to detect if exoplanet exists; further observe it to see if it has a solar system similar to earth’s to further explore the possibility of life beyond earth.

From the short Scientific American article “The Earth Next Door,” name and briefly explain three potential problems Proxima b might have due to its close orbit that may prevent the planet from providing a stable environment in which to host life? 

1- tidal heating causes it to be hot

2- harsh x-rays and UV radiation could strip its atmosphere

3- layer of hydrogen that gradually evaporates under harsh starlight

From the Scientific American article "The Galactic Archipelago," explain why it would be difficult for us to determine whether or not an advanced civilization lived on our planet millions of years ago. What is an example of evidence we might plausibly find that would indicate the existence of a past advanced civilization on Earth? 

radioactive fallout

From the Scientific American article "Alone in the Milky Way," explain two reasons why life is less likely to thrive on planets orbiting stars that are further from the center of the galaxy.

1. Further away you are from center of galaxy, the sparser stars there are. Thus, less stars means less possibility of life even existing 


2. Metallicity (metals / all atoms) is lower when further away from the center meaning that stars have less elements thus making life less possible 

From the Scientific American article "Alone in the Milky Way," although the appearance of life on Earth only a billion years into the planet’s history would make us optimistic about discovering life elsewhere, the development of more complex life (like us) seems to be extremely unlikely because of the history of life’s development since that first single-celled organism appeared. Explain why.

Single celled organisms = only thing existed on earth for 2 billion years so it may not be common for intelligent life to form easily

From the "Crash Course: Exoplanets" video: What was so significant about the discovery of the exoplanet HD 209458b, discovered in 1999? Explain

* It had a transit = once per orbit it passes directly in front of its star so it blocks a little bit of the star’s light and we can detect a dip in the star’s brightness.
* This was the first confirmation of an exoplanet.

From the video "Life Beyond Earth, Part 1," Freeman Dyson explains that there are two possibilities regarding the origin of life. Either it came into being gradually through chemistry and steps we could hope to retrace (and could presumably be reproduced elsewhere) or life is some kind of extraordinary fluke. (a) If the answer to the question of the origin of life is the first possibility, what does that imply about life beyond Earth? (b) What if the answer is the latter possibility?

a) gradual one: then life presumably happens all over the cosmos, and we should find examples of life 

b) if not, then we will not find any other examples of life anywhere near us in our galaxy 

From the TESS Planet Hunter discover video, NASA scientists have created two possible models to represent TOI 700 d, the Earth-sized planet orbiting in the habitable zone of its parent star. They predict that the mostly-rocky planet will have an extra feature in its spectrum that wouldn’t appear in a mostly-water planet model. What is the extra spectral signature?

When starlight passes through a planet’s atmosphere, it interacts with molecules like CO and N to produce distincts signals called spectral lines. 

From the TED talk about ALMA,, one of the ALMA observations discussed is an observation of Carbon Monoxide snow around the newly formed star TW Hydrae. How is this related to the possible origin of life on Earth?

CO2 frozen around the young star; we need to know where the line of CO2 is because comets can pass by and pick up that CO2 and could crash into earth, which might have been one way earth got CO2. 

From the film "Life Beyond Earth, Part 2," explain why it will be easier to communicate (or find) other intelligent alien civilizations if the average lifetime of a civilization is extremely long (millions or tens of millions of years) instead of short (less than 100,000 years or so).

* the longer civilization last, the higher the possibility of overlap will be and possible to find each other.
* The shorter the lifespan of civilization is, the less likely they are to overlap with others.

From lecture, in the Doppler wobble method of exoplanet detection, explain what we observe and how that turns into a graph of radial velocity vs time.

* Periodic variation in stars orbital speed = has unseen planet
* Velocity change = stars speed = planets mass
* Pattern repeats every 4 days, tells us planets orbital period

From lecture, (a) once we have a graph of a star's radial velocity vs time, what two things on that graph do we measure? (b) For each of these two things, explain what property of the companion planet do deduce (explain why is there is a relation between what we measure and the property of the planet).

* Period: larger period = larger star -> planet distance
* Amplitude: planets mass and its distance

From lecture, if we were to encounter or detect evidence (by finding artificial signals through our searches of the sky) another intelligent, communicative civilization besides our own, it is highly likely that that other civilization will be much more advanced than our own. Explain why they would likely be more advanced than us (this is also covered in OpenStax Chapter 30.4).

It is likely they’re more advance because they detected us and communicated with us when we have already been looking for so long

From your textbook's chapter 9.3, describe the evidence in the lunar maria and highlands that indicates the cratering rate on the Moon hasn’t always been constant, but instead there was an early era of heavy bombardment, then a slower, constant rate from that point forward.

The highlands are more cratered but same age as maria -> crater rate must’ve changed

From your textbook's chapter 9.5, describe how radar measurements of Mercury revealed its rotation rate to astronomers on Earth (explain or use a simple diagram to show what the observations would look like if Mercury were rotating slowly vs quickly and explain the difference).

Send pulse 2 planet with particular wavelength because mercury is spinning, some pulse is redshifted and some is blueshifted. 

From your textbook's chapter 10.4, a small sample of meteorites found on Earth’s surface over many years is composed mostly of volcanic basalts.  Explain the two arguments Astronomers have used to deduce that the meteorites likely originated from the surface of Mars. 

* Analysis of tiny gas bubbles trapped inside meteorites match the atmospheric properties of mars.
* Volcanism matches 

from the Scientific American article "Mars in Motion," the "gullies" observed frequently on Mars were originally thought to be some manifestation of flowing water (though there were problems with this hypothesis as mentioned at the opening of the article).  Eventually, the HiRISE mission came up with enough observational data to convince scientists that the gullies are caused by sublimation of carbon dioxide frost.  Explain two lines of evidence that led scientists to this conclusion.

1- the pattern of gullies formed on pole-facing slopes match seasonal distribution of carbon dioxide frost

2- gullies are more active in south hemisphere than north because south winters are longer so more frost accumulates

From the Scientific American article "Mars in Motion," another type of feature observed on Mars is the "Recurring Slope Lineae" (or RSL).  Describe two arguments to suggest these are associated with flowing water (one from page 62, one from page 65).

1- summer with warm temperatures so water can exist
2- subsurface is where water would be because of warm temperatures

From the Scientific American article "How to Search for Life on Mars," (a) describe how the first Viking experiment searched for life in the Martian soil, and (b) explain how the presence of perchlorate in the soil explains the "false positive" results from Viking.

a- Dug up soil and added (carbon compounds) food for microorganisms -> observe co2 release if microorganisms exist in soil 

b- perchlorate also releases CO2 so it made it seem as though the soil was releasing CO2 due to the food, but it was really perchlorate  

From the Scientific American article "How to Search for Life on Mars," describe two important factors that make it more probable for life to be present, which will then help us to select a landing site for this proposed mission to Mars.

1. Salt that would protect biomarkers and salt and water would support life
2. Places that are newly eroded

From the video "Crash Course: Tides," what causes “extra high” high tides, even higher than what you would normally see during Spring tides?  These kinds of tides are called proxigean tides.

when the moon’s elliptical orbit is closer to earth and its a new or full moon

From the video "Venus Could Have Supported Life for Billions of Years: "in the simulation described in the video, Venus is supposed to have started with a thick atmosphere of mostly Nitrogen and oceans of water all over the surface.  What did the simulations show about the long-term evolution of Venus’ atmosphere over the first 3 billion years or so of its history (asking specifically about temperatures and carbon dioxide levels)?

* radiation from the sun increased over time so today Venus receives twice as much solar radiation than earth does.
* Venus maintained stable temperatures for three billion years and its thick atmosphere of CO2.
* Then, it cooled down and carbon was drawn out of the atmosphere and locked into silicate rocks.

From the video "Crash Course - Mars: "why does the narrator argue that life could have potentially formed on Mars even before it formed on Earth, billions of years ago?

The Curiosity rover detected simple organic molecules in a rock sample which means that the ingredients for life were and are on Mars. It also detected a spike in methane, a gas that can be produced by life. 

from lecture, briefly describe the capture theory for the origin of the Earth's moon, and explain two problems with the theory from a scientific standpoint.

Capture theory: earth and moon formed independently; earth captures moon during close encounter


1. Earth's mass and how capture works: as moon falls into earth, it would go so fast it escapes. Object (moon) towards earth would need to slow down significantly -> moon Is too massive to slow down
2. Not believable that they’d have same isotope

From lecture, briefly describe the giant impact theory for the origin of the Earth's moon.  How does the giant impact theory explain (a) the lack of metal in the Moon relative to the Earth, (b) the fact that Earth and Moon rocks have very similar isotope fingerprints, and (c) the relative lack of volatiles in lunar rocks compared to the Earth.

Giant impact theory: big object (like mars) crashes into the earth and knocks a piece of earth into space 


1. Earths mantle is rocky -> lacks metal 


2. Some isotopes fingerprint bc moon is a part of earth 


3. Heating source from impact got rid of volatiles 

From lecture, explain how we use Argon to argue the Earth and Venus originally had similar atmospheres.  Describe the logical sequence that starts with Argon measurements and ends with the conclusion that the two worlds had similar atmospheres originally.

1. Earth and venus have similar amount of Ar 


2. Since Ar abundance doesn’t change over time, then earth and venus had similar amounts of Ar originally 


3. If Ar was same originally, then so was “body” of the rest of the atmosphere 

From lecture, describe the evidence (3 parts) from the Magellan explorer that led scientists to the conclusion that Venus resurfaced itself somehow about 500 million years ago.

1- # of craters on venus = 5x earth → venus’ surface is \~500 million years old

2- crater distribution on venus is uniform not clustered = entire planet was resurfaced at the same time

3- crater appearance is pristine, no erosion, no gradual way to erase craters

From your textbook's chapter 11.2, how do we know Saturn has an additional internal heat source not found on Jupiter?   

* Saturn has twice as much energy as Jupiter so that means that it has an extra heating source.
* The extra heat source is due to the separation of helium from hydrogen. Cold for helium to condense to liquid so it falls back to into Saturn.
* The evidence is from the depletion of helium in Saturn’s atmopshere

From your textbook's chapter 11.3, explain what causes the color difference between the light and dark bands in the atmosphere of Jupiter.

High and low pressure systems -> gas rise up and down

From your textbook's chapter 12.2, why aren't all four of Jupiter's major moons composed primarily of ice, given that ice was by far the most abundant solid substance in the outer solar system?

Jupiter is hot enough to radiate infrared energy that would vaporize material near the planet. 

From your textbook's chapter 13.2, we learn that discoveries small asteroids that may be hazards to the Earth is very difficult, so it is important to know as we find them, how many more are still left to be discovered.  Describe two ways in which we know that our surveys to date have found roughly 90% of these hazardous asteroids larger than 1 kilometer in size.

* Look at the number of larger craters since this tells how many impacts have occurred on Earth. 
* Looking at how often surveys rediscover a previous asteroid.  

From your textbook's chapter 14.1, (a) what is the radiant of a meteor shower?  (b) What causes the radiant effect that makes meteor trails all seem like they originate from (or point back towards) a specific place on the sky? 

a) Radiant: parallel paths between dust particles and pebbles   

b) “parallel paths of meteors move together and look like they diverge from one point in the distance 

From the “Interstellar Interlopers” article, describe three differences between the 2nd interstellar object (2I/Borisov) and Oumuamua that indicate Borisov is more like the kind of object we expected to find.

* No noticeable changes in light curve, unlike the changes in Oumuamua’s curve. 
* Has a comet tail, unlike Oumuamua. 


* Has lots of ice.  
* Breaks apart visibly like other planets.  

From the video "Crash Course: Jupiter," explain the two different theories we currently have about how Jupiter formed (and what kind of core it has).

* Disk was thick and rich with material, forming large protoplanets. This would mean Jupiter had a rocky metallic core that would draw gas into it.
* Disk collapsed into pieces that would eventually crash and come together to create planet. Jupiter has no core.

From the video "Crash Course: Saturn," explain what properites of the lakes on the surface of Titan make us think there is active weather in the atmosphere of Saturn's moon Titan.

It was observed that the lakes and channels on titan were of liquid methane meaning that there is weather on titan driven by methane not by water like on earth. The lakes have moving shorelines which prove weathering occurs.  

From the video "Kingdom of Saturn," name and explain three observed properties of Saturn's moon Enceladus that led us to believe there is liquid water in the interior near the South Pole of the moon.

* Whitest body in the solar system.  
* South pole has bent field lines.  
* Images show region is south pole resurfaced.

From the video "The Bizarre Characteristics of Titan," explain what is thought to be the cause of Titan's orbital eccentricity and tilted orbital plane.

Big collisions are thought to be the cause 

From the video "Asteroids," from the Arizona site and the Sudbury site, the video discusses 3 additional features, aside from those in the previous question, that are common indicators of impact sites.  Describe each of these three, and briefly explain how the impact process results in each feature.

* Iridium is a rare metal on Earth, but abundant outside of Earth 
* When an asteroid, meteorite, comet strikes, the energy resulting from impact is so intense that hole is instantly created.  
* Deformed rocks like shatter cones

From lecture, explain why Iridium is more common in the interior of the Earth than in the surface rocks and crust of the Earth.

Iridium big signature of impact: 

* On surface, iridium = 1 part / billion 
* Earth as a whole = 100 parts / billion 
* More common on floor: tertiary (1/billion), boundary layer 1000/billion, cretaceous 1/billion 

From lecture, normally, when a comet's orbit is different than we expect, it is because of something like the Yarkovsky Effect mentioned in question 6.19.  Explain two reasons why we do not believe cometary jets are the cause of Oumuamua's peculiar path through the solar system.

* No jet seen.  
* Rotation pattern does not change.  

From lecture, explain what are the Kirkwood gaps and how they are formed.  As part of your answer, explain why an asteroid in one of the gaps would be affected so radically while an asteroid just to one side or the other of the gap isn't affected.

* Saturn rings (orbit in circles) have gaps like in asteroid belt (orbit in elliptical) -> found by plotting due to resonance which is a natural frequency
* Particles in the gap would have a close encounter with mimas at the same place in their orbit every 2 orbits = resonance which is a natural frequency
* Particles with period = 14 hours is closer to mimas but feels forced from mimas at different points along its orbit = no energy transfer

From lecture, explain the four lines of evidence that indicate some kind of catastrophic event in the Saturn system about 100 million years ago.

* Titan’s surface is about 100 million years old.  


* Titan’s large mass and energetic orbit suggest a large collision in the past.  
* Saturn’s rings are mostly ice with minimal dust.  
* Simulations show rings get darker from dust after 100 million years.  

From lecture, explain the four lines of evidence that indicate some kind of catastrophic event in the Saturn system about 100 million years ago

* Titan’s surface is about 100 million years old.  
* Titan’s large mass and energetic orbit suggest a large collision in the past.  
* Saturn’s rings are mostly ice with minimal dust.  
* Simulations show rings get darker from dust after 100 million years.