Astro Final
Q3.59* 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).
The lifetime of an average civilization indicates that other civilizations are likely much older because earth's civilization is so young.
Q2.29* From the video on climate science, explain how perovskites may fundamentally change the way we harvest solar energy, how it differs from using silicon.
They are a cheap and fast way to paint a solar surface that will generate a current. It is more flexible and easier to work with
Q2.31* 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).
They found the no till farming was actually better for the soil and absorbs more carbon because the leaves are a protective later to the topsoil
Q3.39* 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?
They predict that the mostly-rocky planet has CH4 (methane) in its atmosphere
Q2.19* 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?
They were asteroids and wouldn't be considered planets as there are way to many of them and it would be confusing to have over 135,000 planets
Q4.40* 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)?
Venus' atmosphere maintaned a stable temperature. It had a thick CO2 atmosphere which has slowly been drawn out.
Q4.25* 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) Add starch and sugars in soil -> if microbes lived, they would consume the food and release carbon b) Perchlorate produces bleach-like compounds when exposed to cosmic rays, producing carbon in the process
Q1.50* From lecture, what is (a) the major benefit and (b) the major drawback of a system of knowledge based upon scientific principles?
a) Benefit: Allows competing groups/theories claims to reach a consensus on what is "most true." b) Weakness: No absolute truth -> could be wrong
Q4.50* 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.
a) Mars size object collides into earth and break a piece of earth into orbit (contains low metal because it is outer layer of earth) b) Moon is after all a piece of the earth. c) Heat from impact would have gotten rid of volatiles.
Q1.43* 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) Measures tree carbon content by using computer models b) Trees are soaking up about ¼ of the extra CO2 emitted annually
Q1.7* 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) The one advantage of irrefutable ideas is that they are universal absolute truths (unchanging). b) The problem is that irrefutable ideas can block the progress and discovery of new truths. When two ideas conflict people cannot reach a resolution as to which is better.
Q1.28* 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) Warming ground leads to plants growing faster, which means more CO2 will be absorbed by these plants. b) In the Summer plants absorb more C02 whereas in winter plants don't grow leading to a net excess of C02.
Q5.16* 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) point in the sky from which meteor shower particles appear to originate/diverge from. b) dust particles and pebbles that makeup meteor showers are moving together in space before they encounter Earth, so their parallel paths seem to come from a specific place in the sky
Q2.13* 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) the more impact craters it has the older the planet is b) 1. half life 2. current composition... number of parents and daughters 3. original composition
Q1.54* 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).
image
Q5.4* From your textbook's chapter 11.3, explain what causes the color difference between the light and dark bands in the atmosphere of Jupiter.
light bands -> upwelling air, low-pressure, white ammonia clouds dark bands -> atmosphere moves downward, high-pressure, few ammonia clouds
Q5.50* From lecture, explain why Iridium is more common in the interior of the Earth than in the surface rocks and crust of the Earth.
most Iridium sank into the core when the earth melted
Q3.5* 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).
small planets -> know they're hard to detect and we are missing a bunch. Likely 5x more than what we observe.
Q2.49* From lecture, two other variables that are associated with costs are subsidies and future costs. Explain what subsidies are and why they help to make fossil fuels cheaper, and explain why fossil fuel use may have costs that are eventually paid by later generations (even though they will get no benefit from using the energy, obviously).
subsidy - government assistance => keep price of gas down and raise standard of living rise in temp, sea levels etc. will be the future generations problem.
Q5.30* 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.
1) magnetic field lines are bent -> indicate salty ions in water 2) surface smooth without craters -> water resurfaced 3) 100 degrees warmer in south pole -> heat signature
Q2.25* 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) rich in organic compounds 2) hazardous orbit that could hit the earth => deflect if it comes
Q5.41* 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.
1) shocked quartz (evidence of shockwaves have fractured crystal structure) 2) Shatter cones (shockwave remnant in rocks) 3) Iridium enrichment
Q2.5* 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) electrolyzer splits H20 -> store hydrogen in container b) You can combine H2 and O to create energy
Q3.37* 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) it should happen all over the cosmos, and we should be able to find life b) if it was a fluke, we won't find life elsewhere
Q1.27* 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) microbes can access a fraction of the carbon b)It is already in a semi-decomposed state that microbes only further degrade slowly
Q3.53* 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).
a) period and amplitude b) period shows the distance between the star and planet, amplitude shows the mass of the companion planet because the larger the planet the more the star moves around
Q2.9* 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) radio waves have a long wavelength that messes with resolution b) linking multiples radio telescopes together electronically to create one large telescope to sharpen the image
Q5.21* 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.
- Borisov doesn't have an extreme light curve -> normal shape - doesn't have a tail/coma - has a lot of ice/frozen water
Q5.51* 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.
- Kirkwood gaps are gaps in the distribution of asteroid orbital periods and are caused by Jupiter adding energy to asteroids and changing their orbits. - resonance effect from Jupiter doesn't allow for resonance gap
Q3.42* 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?
- comets can pick up carbon monoxide and organic molecules by passing through clouds that surround stars - the comets crash into planets, depositing the organic molecules - we believe one possibility for life on earth is things carrying organic molecules and elements crashed into earth
Q4.37* 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.
- during the new/full moon, the moon's tidal force aligns with the sun's, reinforcing it and making the pull stronger - the moon orbits on an ellipse, so if it is closer during this time as well, we will see extra high high tides
Q4.13* 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).
- if mercury is not moving it bounces back narrow -if mercury is rotating some light will be redshifted and blueshifted - how fast = more shifting
Q5.23* 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).
- several large protoplanets were forming, collided, and stuck together to start Jupiter's growth, so it would have started with a rocky metallic core and then gotten big enough to draw in gas - disk collapsed in several places to form huge, distorted clumps which then collided, stuck, and formed Jupiter, so it might not have a core at all
Q3.3* 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?
- the depth of the transit, or amount of light blocked, depends on the size of the planet - using both the Doppler and transit techniques, you can derive the average density, larger mass and radius means gas and liquid
Q3.30* From the "Crash Course: Exoplanets" video: What was so significant about the discovery of the exoplanet HD 209458b, discovered in 1999? Explain.
- the first independent confirmation of an exoplanet - had only a 3.5 day orbit and we could view it edge-on, so we could use the Doppler shift
Q5.28* 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.
- the shorelines of the lakers are changing shape from erosion and weather
Q5.35* 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.
- victor of orbital collisions -result of collisions
Q3.27* 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.
- we only saw more complex organisms 550 million years ago, even though there were single-celled organisms on earth around 3.5 billion years ago - the odds of finding life in a much earlier stage is more likely than finding complex life
Q3.18* 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?
-Biased in finding planets close to their orbital star -Shows dusty disks which can infer the shape of the planet through structures and patterns
Q2.23* 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.
-carbonaceous chondrites contain complex organic molecules that are easily destroyed by heat, therefore they have to be far from the sun
Q4.58* 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) Crater density on Venus is 5x larger than on earth -> surface is 5x older = 500 million years 2) Crater distribution is uniform (unlike moon's highlands/maria) -> whatever event reset the surface was global 3) Craters on Venus show no signs of erosion/decay -> whatever erased craters was sudden
Q2.34* 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) Hard to predict all possible consequences of big change (like making clouds brighter) 2) Gives everyone an excuse to do nothing
Q4.28* 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) Look for some place that has ice -> acts as a shield 2) Look for some place with sandy soil rather than rock -> need to live below the surface as there is too much solar radiation to survive on the surface.
Q1.29* 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) Melted ice exposes more dark ocean surfaces, which leads to less reflection and more warming. 2) Ice prevents heat/moisture underneath the ice from being released, if it melts that heat is all released. 3) Thawing soil releases large amounts of heat/gases formerly trapped by permafrost into the atmosphere.
Q4.23* 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) RSLs favor unusual environments, mainly middle latitudes on warm slopes in the south where summers are hotter 2) peak RSL appearance corresponds not with peak surface heat, but when subsurface temperatures are highest and water is most likely in the subsurface
Q4.17* 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.
1) Solidification age of rocks matches with the surface of Mars 2) If you excavate tiny bubbles from a meteorite they match the isotope of Mars atmosphere
Q5.59* From lecture, explain the four lines of evidence that indicate some kind of catastrophic event in the Saturn system about 100 million years ago.
1) Surface of Titan age ~ 100 million years 2) Titan is too large to form independently from debris near Saturn, so it is likely the product of a merge/collision of moons 3) Ring system also result of collision within last 100m years 4) Age of rings can be estimated by amount of dust vs ice. Over time, dust builds up. "Fust age" ~ 100m years
Q1.19* 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) There is evidence of greater warming at the surface of the sea than deeper explaining how greenhouse induced warming is influenced by the overlying atmosphere 2) Troposphere has warmed while the stratosphere has cooled which explains how natural causes would have warmed both layers, not just one.
Q5.13* 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.
1) look at the numbers of larger craters on the dark lunar maria. 2) see how often the surveys (which are automated searches for faint points of light that move among the stars) rediscover a previously asteroid
Q4.22* 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) seasonal distribution of frost matches gullies 2) happen more often in the south since winters are colder in the south, so CO2 frost accumulates more
Q3.20* 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 effects could cause Proxima b to rotate once per orbit -> heat and light on only one side of the planet 2) Proxima Centauri continually produces solar flares that could stop Proxima b of its atmosphere 3) Tidal heating -> friction produced inside a planet by flexure from its star's tidal tug. This would cause all oceans on the planet to boil off
Q5.49* 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.
1) we don't see gas leaving Oumuamua 2) a jet is likely to change the rotation/light curve but there wasn't a change.
Q1.22* From the article "The Last Great Global Warming," describe the two chemical changes that occurred in the oceans due to the buildup of CO2 in the atmosphere.
1. Acidification occurred when oceans absorbed CO2 2. As temperatures rose in the ocean because of absorption the O2 supply decreased.
Q1.21* 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 occurred (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. The ocean's warmth traveled and caused the seabed to thaw, which releases frozen methane deposits, and in turn releases CO2 into atmosphere. 2. Droughts led to forest fires, which release CO2 into atmosphere. 3. When the permafrost defrosted, microbes eat remains and release methane into atmosphere.
Q4.55* 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.
Argon Reconstruction: 1) Earth and Venus have similar Argon abundancies today 2) Since Argon can't be removed, we assume Earth and Venus originally had similar Argon abundancies 3) If origional argon is the same, then the origional CO2, water, methane, etc. were the same.
Q1.23* From the article "The Last Great Global Warming," how do we know the temperature of the water at the time these ancient sediment deposits occurred?
As sediment layers form, skeletal remains of life are trapped. These have signatures of chemical compositions which are used to decipher temperature.
Q2.45* 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.
As the other planets got larger Pluto got pushed further away and formation was very difficult to keep going once it was further from sun (past Neptune roughly) less material in outer solar system.
Q4.49* 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 - shortly after earth formed, a big object crashed into it and a chunk of mantle flew off into space and formed the moon 1) If the moon formed independently of Earth then the Earth and moon would nod have similar isotope fingerprints. 2) Capture is physically difficult because some force would need to slow moon.
Q2.24* 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.
Concordance of solar-nebula dust map with structure of certain T Tauri system is similar to ours
Q1.35* 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.
Gravitational pull would have to be constant across the disk which it isn't.
Q1.3* 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.
I would explain that the planes landed for military reasons and to drop off supplies during the war. The planes will no longer land or drop supplies again no matter how many rituals take place because the war has ended.
Q3.52* 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.
IMAGE
Q3.49* 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).
If lifetime is longer there are more chances our lifetimes could overlap because timelines are long enough to overlap.
Q4.12* 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.
If the cratering rate had been constant then the age should be proportional to the number of craters and thus the highlands would have to be 10x older.
Q1.42* 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).
Looks for clues in seashells. Encoded in each layer is chemical information about the temperature of the water. As shells grow they incorporate oxygen from the sea water. Colder water = more oxygen 18 vs oxygen 16
Q4.43* 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?
Mars is smaller than earth and cooled more quickly, so it's not crazy to think that life possibly formed there. The Curiosity rover detected organic molecules in a rock sample, which shows the ingredients for life on Mars exist.
Q3.22* 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?
Natural world hides traces of historic life. Look for certain artificial chemicals.
Q1.18* 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.
Only the computer models that factor in human impact show the correct change in temperature indicating that we are largely responsible.
Q5.3* From your textbook's chapter 11.2, how do we know Saturn has an additional internal heat source not found on Jupiter?
Saturn emits more heat than Jupiter does therefore we know there is an additional heat source
Q2.15* 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.
Some meteors have weathered over time and hard to distinguish because they look just like rocks, but iron meteorites are more obvious and stick out
Q3.25* 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.
Stars are sparser, and metallicity is lower so there are fewer rocky planets. And they are most likely out of the galactic habitable zone range.
Q5.6* 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?
The formation caused a great deal of infrared energy which vaporized any nearby ice.
