Midterm possible questions

Q: Give an example of the kinds of features the spacecraft Dawn has observed on large asteroids. A: 4 Vesta is the largest asteroid and one of the brightest in the sky to the naked eye. Dawn discovered that 4 Vesta has a meta-rich core that is half its diameter. It also found that the biggest mountain on 4 Vesta is bigger than the one on Earth. Q: What is an asteroid family? When two asteroids of unequal size collide, will the fragments come from the larger body or the smaller one? A: Family=The breakup of asteroid into a collection of fragments. When two asteroids collide, the larger asteroid will experience greater stress meaning the collision fragments will usually come from the larger one. Q: Do near Earth objects have circular or elliptical orbits? A: All of them have highly elliptical orbits. Q: De2ne Atens, Apollos, and Amors. A: Atens: Asteroids with orbits less than 1 AU - meaning they are within the orbits of Earth. Apollos: Asteroids that cross the Earth's orbit. Amors: Asteroids that cross the orbit of Mars and get close to Earth's orbit. Q: What is the de2nition of a PHA? A: Potentially Hazardous Asteroids (PHAs) with minimum 150 m diameter and 0.05 AU to Earth. Q: What are Trojan asteroids? A: They are asteroids that are about 60 degrees ahead and behind Jupiter in Jupiter's orbit. Q: What size of an impactor could cause global eGects on Earth? A: Minimum 1km - Apollo asteroids. Q: What is the Torino scale? lOMoARcPSD|32296826

What techniques do we use to analyze a meteorite? What can we learn from the test? - Petrographic microscope: IdenKfy mineral composiKon of meteorite. Electron micropobe: - Uses Kny beam of electrons to idenKfy what elements are present. Mass spectrometer: - Measures radioacKve isotopes to see how old sample is. End of Chapter 4 DeJniKons of a gas giant planet (Jovian Planet) - A large, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in gas or liquid state. What are the 4 gas giants in our solar system? - Jupiter, Saturn, Uranus, Neptune What are the common features shared by gas planets? - low density - very hot core - Mainly made of hydrogen and helium, my hydrogen. - All have satellites/rings - All rotate rapidly resulKng in strong atmospheric wind. How/when do the gas giants form? - Either formed in the Jrst 10 million years of solar system or did not develop. - VolaKle and liquid elements - grew via gravitaKonal a^racKon and increased by pulling greater and greater quanKKes of volaKle liquids to them. What did we learn by watching the Shoemaker-Levy 9 comet impacKng Jupiter? - 1. It be^er allowed us to study and represent Jupiter's atmosphere. - 2. It reminded us that planets are being hit by large objects all the Kme. How do we know that Jupiter is big? - We know that Jupiter is big because it looks big. Io's shadow displays visible contrast to Jupiter's size. How do we know that it is hot? Why does it have a high heat ]ow (what is the internal heat engine) - We know that it's hot because it emits 1.7 x energy that it receives from sun - meaning it has a hot core that generates energy. - It has strong wind circulaKon. Describe what we observe happening on Jupiter's surface? - There are very strong winds. the Great Red Spot (GRS) is a cloud of rotaKng storm caused by heat rising upwards. Why did scienKsts crash the Galileo spacecraU into the surface of Jupiter? What did we learn during this descent? - Galileo was crashed to the surface of Jupiter because it could contaminate the icy crust of Europa that main contain microbial life. lOMoARcPSD|32296826

What are the rings composed of? Do other gas giants have rings? Compare di_erences in formaKon of rings among the gas planets - Saturn's rings are made of water parKcles of ice; some dirt. Saturn's rings are extremely bright, wheres uranus and neptunes' rings are darker. Why are the rings orbiKng Saturn's equator rather than spread in a haze about the whole planet? - Due to Saturn's gravitaKonal pull, its gravity is centered at the equator and compressed at the pole - therefore there's a greater gravitaKonal pull near the equatorial zone. Do we know what causes the appearance of "spokes" on the B ring? - Spokes are dark radial features that move in pa^erns on the B ring. - It might be a seasonal phenomenon as it disppears and reappears again, but we don't know the reason. Do collisions of parKcles in the rings make parKcles larger or smaller? Explain - Collisions of parKcles in the rings make bigger parKcles smaller and smaller parKcles bigger. Outline the evidence that suggests the material in Saturn's ring is young - Uniformity of material in rings - Ice blocks re]ecKng are fresh looking (no dust) - Can't be that old What are the arguments that suggests the rings might be old? - Rings are not always uniform all the way around. Regions that are young cannot represent its age. What is a possible source of the water/ice in its rings? - The rings were once a water-ice, rocky-core satellite of Saturn which was ripped apart and formed the rings. Titan has an atmosphere and conKnents making it like Earth. Let's compare their properKes: 1. What is the composiKon of Titan's atmosphere? - 98.4% nitrogen, just like Earth 2. Is the surface hot or cold? - Cold 3. What is special about the volcanic acKvity on Titan? - The volcanoes are cryovolcanoes, which erupts cold water/ice instead of lava. 4. What is the source of methane in the atmosphere on Titan vs Earth? Methane in the atmosphere of Titan are from volcanoes. Methane on earth are from biological life. 5.What are Titan's dunes composed of? - Methane crystals 5. Does Titan have the ingredients required for life? - Not now, even it may contain organic molecules, there is no carbon dioxide and the surface is too cold. when the Sun turns into a red giant which heats up its surface, it may. lOMoARcPSD|32296826

- Oort Cloud: further than Kuiper Belt near the edge of the S.S What is the name of the spacecraU that recently visited Pluto? - New Horizons What is Planet X? - The mysterious planet 6 degrees away from pluto. Is Pluto always further from the Sun than Neptune? Why or why not? - Not always, every 248 years, Pluto swings inside orbit of Neptune and stay there for 20 years - which is then closer to the sun. What 4 kinds of ice are found on Pluto's surface? - Methane, nitrogen, carbon monoxide, carbon dioxide Why is Pluto's surface not heavily cratered? - Because it is cold enough that everything freezes over. In Tombaugh Reigo smooth plain called Sputnik Planum, the ice are very young and are acKve. Does Pluto have an atmosphere? - It has a thin atmosphere. It is so cold that the vaporizaKon of nitrogen, carbon monoxide, and methane to form a thin atmosphere. What is Pluto's interior? - frozen nitrogen, water ice, and silicate rock. Is Charon a satellite of Pluto? - Charon is Pluto's largest satellite - it orbits pluto in near circular orbit, their gravitaKonal balance point is between them, meaning pluto has a really weak gravitaKonal pull - and can argue that Charon is not a satellite. Why is there almost no methane on Charon, while Pluto has lots? - Charon is too small to hold o_ methane therefore gas escapes. Pluto catches a lot of it leaking o_ Charon. What is the main kind of ice on Charon? - Water ice Does Pluto have satellites? - 4 - Nix, hydra, Kerberos, Styx What do we know about Eris Largest Plutoid - li^le bigger than Pluto. - Composed of methane ice. What is the Sca^ered Disk? - Disked shaped region beyond the Kuiper belt with objects that have random orbits out at the edge of solar system - starts at Kuiper Belt and extends out. End of plutoids What are comets? - Small, icy masses that orbit the sun that are greater than 100 m in diameter Where do comets come from? - Kuiper Belt and Oort Cloud lOMoARcPSD|32296826

- DNA: a form of nucleic acid that carries geneKc informaKon of all organisms. It's primary role is to contribute informaKon to producKon of chemical reacKon in cells. - RNA: carries out coded instrucKons given by DNA. Why is life on earth carbon based instead of silicon based? - Carbon atoms bond to form complex, stable chains to uKlize energy. Describe how the process of natural selecKon results in evoluKon of species? - The species with a disKnct advantage will survive and be passed on to o_springs; which enhances the enKre species. Merciless at individual, but gives species best chance of survival. What is our deJniKon of life? -1. Cellular organisms -2. Carbon/Water based -3.Contain geneKc informaKon -4. Undergoes metabolism and adapts to environment -5. Respond to sKmuli and undergoes natural selecKon/evoluKon. What was the Miller-Urey experiment? What did he create and what was the signiJcance? - Demonstrated how inorganic elements could combine with necessary requirements to form organic chemicals. Used lightning to represent the past atmosphere and amino acids appeared. What evidence of life has been found in meteorites? - Amino acids + organic compounds, same as the one produced in the Miller Urey experiment. What is primordial soup? - a soluKon rich in organic compounds in the primiKve oceans of the earth, from which life is hypothesized to have originated. How/where might amino acids link together to form larger molecules - Compounds dissolved and linked together to form molecules in earth's ocean How old is the oldest fossil? - 3.5 billion years old Stromatolites, some of the earliest complex organisms, produced oxygen which was toxic to them - how did they survive? Is this process sKll happening today? - The ocean back then was full of iron, once the oxygen was produced, it was instantly dissolved. It would not happen today because the ocean changed. What is the di_erence between a prokaryote and eukaryote - Prokaryote: single-celled organisms lacking complex internal structures - Eukaryote: MulK-celled organisms with nucleus, and more complex features; live by respiraKon through oxygen for energy. Why do we need ozone? - Blocks ultraviolet radiaKon from reaching the surface which breaks down Amino Acids. At least 2% oxygen is needed in the atmosphere to produce ozone. lOMoARcPSD|32296826

2. Asteroid 3. Meteoroid 4. Meteor 5. Meteorite - Answer: 1.c 2.b 3.d 4.e 5.a Which of the following is a classi2cation scheme for asteroids?  A. C-type, S-type and M-type  B. irons, stony-irons, and stones  C. siderites, siderolites, and aerolites - Answer A How old are most chondrites? - 4.56 billion years old You are sitting in your backyard in Toronto, and a meteorite lands in your backyard. You are allowed to keep it. - True S-Type asteroids have high - Silicon content The spacecraft that visited Vesta in 2011-12 and arrived at Ceres in 2015 is called - dawn . The most common meteorites are - Chondrites Most new meteorites are typically found - in desert regions, such as the Sahara and the Antarctic ice sheet. An imminent collision of an asteroid into Earth, with disastrous results would be given a 1 on the Torino Scale. - False Match the diGerent types of Near Earth Object to their orbital paths: 1. A. their obit is greater than 1 AU and crosses that of Earth 2. B. their orbits are less than 1 AU (though they can cross Earth's orbit) 3. C. they commonly cross the orbit of Mars, but don't quite reach Earth's orbit 1- Atens 2- Apollos lOMoARcPSD|32296826

- Dysnomia Many years after Lowell worked out the parameters, Pluto was located within a half- dozen degrees (of arc) of the location he predicted. - True The 2rst comet to be photographed was - The Great Southern Comet According to recent studies, most comets likely originate from - The scattered disk / Oort Cloud The great mass of Pluto aGects the orbit of Neptune and Uranus. - True The solid, central part of a comet is called the - nucleus Pluto is thought to be partly made of rock. - True Pluto is classi2ed as a (select all that apply) A. Trans-Neptunian object B. Asteroid C. Dwarf planet D. Plutoid - Answer:A,C,D Charon is Pluto's only satellite. - False Icy bodies located in the Oort Cloud are diGerent from comets nearer to Sun because - They have no tails The mountains on Pluto at the edge of Sputnik Planum are composed of - . water ice The ion tail of a comet points - away from the Sun The Rosetta mission and its Philae lander were the 2rst to [select all answers that apply] A. land on a comet B. collect a sample of cometary material C. image a comet nucleus D. orbit a comet - Answer: A,D The vapour surrounding the nucleus of a comet is called the coma (one word; no point for incorrect spelling!). - Coma Sedna is - A Trans-Neptunian object Eris is approximately half the size of Pluto. - False The Eta Aquarids shower is associated with which comet? - Halley Quiz 7: lOMoARcPSD|32296826

Besides Earth, which planet in the Solar System would have the highest potential to have developed life? - Mars Cambrian fossils are restricted only to aqueous environments. - True Stanley Miller and Harold Urey determined that - Amino acids could be formed from early-Earth molecules You are a - Eukaryote Free oxygen is harmful to anaerobic organisms. - True Do species always evolve to higher intelligence? - No, they evolve to adapt to their environment. ALL life on Earth is - Carbon based Viruses are alive. - False The layered structures built by blue-green bacteria are called - Stromatolite Hot stars have larger habitable zones. - True On Earth, it likely took about how many years for all the dissolved iron in the oceans to be used up? - 2 Billion Binary star systems are more likely to host habitable planets than single star systems. - False The primary role of ribonucleic acid (RNA) is to - Deliver instructions given by DNA In any species, an oGspring born with DNA altered by something like cosmic radiation is called a - Mutant Bacteria are alive. - True To form an ozone layer, the atmosphere must have a concentration of at least how much oxygen? - 2% The satellite of Jupiter with greatest chance of supporting life is - Europa Natural selection bene2ts the - Species We de2ne life as cellular organisms that (select all that apply) A. are carbon- and water-based B. respond to stimuli C. possess the abilities to undergo metabolism D. contain genetic information suscient to reproduce E. adapt (through natural selection) to their environment in successive generations F. use oxygen to produce energy lOMoARcPSD|32296826

- Answer: A,B,C,D,E Let's say that a planet in orbit around Tau Ceti is inhabited by an advanced civilisation. If we send a radio broadcast today, and the recipients reply with their own radio broadcast as soon as they receive ours, when could we expect to receive that reply? - About 24 years Study guide with chatgpt answers: Unit 4 intro: 1. Where in our solar systems do many asteroids reside?  Many asteroids reside in the asteroid belt, which is located between the orbits of Mars and Jupiter. 2. Why is there an asteroid belt? How did it form?  The asteroid belt is thought to have formed from the leftover material in the solar nebula that did not form into planets. The gravitational pull of Jupiter, the largest planet in our solar system, prevented the material in the asteroid belt from coalescing into a planet. 3. Are all meteorites from the asteroid belt?  No, not all meteorites are from the asteroid belt. Some meteorites come from other sources such as comets, the Moon, and Mars. 4. De2nitions: Asteroid, Meteoroid, Meteor, Fireball, Meteorite  Asteroids are small, rocky objects that orbit the Sun, typically found in the asteroid belt. Meteoroids are small particles in space, typically smaller than asteroids, that can become meteors upon entering Earth's atmosphere. Meteors, also known as shooting stars, are streaks of light in the sky created by a meteoroid burning up in Earth's atmosphere. Fireballs are particularly bright meteors that can sometimes produce a sonic boom. Meteorites are meteoroids that survive the passage through Earth's atmosphere and land on the surface of the Earth. 5. You do not need to know how to calculate estimates for planetary orbits using the Titius Bode Law, but please be aware that such a law exists – what does it allow us to predict?  The Titius-Bode law is an empirical rule used to estimate the distance of planets from the Sun. It allows us to predict the distance of a planet from the Sun based on a simple mathematical formula. However, the law is not perfect and does not accurately predict the distances of all planets in our solar system. 6. It’s important to learn whatever we can about asteroids because a. They represent very primitive material left over from formation of the Solar System b. Much water and organic material came to Earth from them c. Sooner or later a large asteroid impact is likely to put an end to many terrestrial species (including humans)  All of the above reasons are important for studying asteroids. By studying asteroids, we can learn about the early history of the solar system and the conditions that led to the formation of planets. Additionally, asteroids may have lOMoARcPSD|32296826

brought water and organic materials to Earth, providing the building blocks for life. Finally, understanding the potential impact of large asteroids is important for planetary defense and mitigating the risks to life on Earth. Chapter 12: Asteroids Where are most asteroids found in the solar system? - Most asteroids are found in the asteroid belt, which is located between the orbits of Mars and Jupiter. What are asteroids and meteorites thought to represent? (e.g. age and material) - Asteroids and meteorites are thought to represent very primiKve material leU over from the formaKon of the solar system, roughly 4.6 billion years ago. They can provide informaKon about the composiKon and condiKons in the early solar system. Why did the asteroid belt form between Mars and Jupiter? - The asteroid belt is thought to have formed from the leUover material in the solar nebula that did not form into planets. The gravitaKonal pull of Jupiter, the largest planet in our solar system, prevented the material in the asteroid belt from coalescing into a planet. What are the Kirkwood gaps? - The Kirkwood gaps are regions in the asteroid belt where the gravitaKonal pull of Jupiter disrupts the orbits of asteroids, causing them to be cleared out of those regions. If all the meteoroids and asteroids in the main asteroid belt coalesced, would there be an addiKonal Earth-sized planet between Mars and Jupiter? - It is unlikely that all the meteoroids and asteroids in the asteroid belt could coalesce into a single planet. However, if they did, the resulKng planet would likely be smaller than Earth. What is the di_erence between C, S, and M type asteroids? - C-type asteroids are carbonaceous and are thought to be among the most primiKve asteroids. S-type asteroids are composed of silicates and are thought to be more common than C-type asteroids. M-type asteroids are metallic and are thought to have a core of iron-nickel. Why are some asteroids metallic while others are not? - Some asteroids are metallic because they are thought to be the remnants of the cores of ancient planetesimals, while others are not metallic because they are thought to be the remnants of the crusts or mantles of these bodies. Are the most primiKve asteroids closer to Mars or Jupiter? - The most primiKve asteroids are thought to be closer to Jupiter. How can asteroids be classiJed using albedo and spectral analyses? There is no need to memorize the names of speciJc types of asteroids. - Asteroids can be classiJed based on their albedo, which is a measure of their re]ecKvity, and their spectral properKes, which reveal informaKon about their composiKon. lOMoARcPSD|32296826

Why are the most plenKful asteroid types (carbonaceous chondrites) the least common meteorites found on Earth? - The most plenKful asteroid types, carbonaceous chondrites, are the least common meteorites found on Earth because they are more fragile than other meteorites and are easily destroyed during atmospheric entry. What is a di_erenKated body? - A di_erenKated body is a celesKal body that has a layered structure, with a core, mantle, and crust. Examples of di_erenKated bodies in our solar system include Earth, Mars, and the Moon. Give an example of the kinds of features the spacecraU Dawn has observed on large asteroids. - The spacecraU Dawn has observed a variety of features on large asteroids, including craters, mountains, ridges, and other geological formaKons. What is an asteroid family? When two asteroids of unequal size collide, will the fragments come from the larger body or the smaller one? - An asteroid family is a group of asteroids that share similar orbits and are thought to be the remnants of a larger parent body that was disrupted by a collision. When two asteroids of unequal size collide, the fragments are more likely to come from the larger body. 15.What kind of orbits do near-Earth objects have? - Answer: Near-Earth objects can have either circular or elliptical orbits, but generally, their orbits are more eccentric than those of other solar system objects because of gravitational perturbations from other planets. 16.What are Atens, Apollos, and Amors? - Answer: Atens, Apollos, and Amors are diGerent types of near-Earth asteroids based on their orbital characteristics. Atens asteroids have orbits that cross Earth's orbit, but they spend most of their time inside Earth's orbit. Apollos asteroids have orbits that cross Earth's orbit but spend most of their time outside of Earth's orbit. Amors asteroids have orbits that come close to Earth's orbit but never actually cross it. 17.What size of an impactor could cause global eGects on Earth? - Answer: The size of an impactor needed to cause global eGects on Earth depends on many factors, such as the composition of the impactor, the angle of impact, and the location of impact. However, generally, an impactor with a diameter of at least 1 kilometer could cause global eGects, such as climate change and mass extinctions. 18.What are Trojan asteroids? - Answer: Trojan asteroids are a group of asteroids that share Jupiter's orbit but remain in stable positions at two speci2c points in Jupiter's orbit, known as the Lagrange points. There are also Trojan asteroids associated with other planets, such as Mars and Neptune. 19.What is the de2nition of a PHA? - Answer: A potentially hazardous asteroid (PHA) is an asteroid with an orbit that comes close to Earth's orbit and is large enough to cause signi2cant damage if it were to collide with Earth. PHAs have a minimum orbit intersection distance with Earth of 0.05 astronomical units or less and a diameter of 140 meters or more. lOMoARcPSD|32296826

20.What is the Torino Scale? - Answer: The Torino Scale is a system used to rate the potential impact hazard associated with near-Earth objects. It ranges from 0 to 10, with 0 indicating no likelihood of impact and 10 indicating a certain impact with global consequences. As the scale increases, the potential impact becomes more serious, but the scale does not indicate the likelihood of an impact occurring. Chapter 13- Meteorites What are the sources of meteorites that we have found on Earth? How representaKve of the sources are the samples? - Meteorites that we have found on Earth come from asteroids, the Moon, and Mars. These samples are generally representaKve of the bodies they come from, but the process of reaching Earth can alter their composiKon. What is the di_erence between a Jnd and a fall? - A "Jnd" meteorite is one that has been discovered without any indicaKon of its fall to Earth. A "fall" meteorite is one that has been observed as it fell through Earth's atmosphere and then recovered. What is the di_erence between irons, stony-irons and stones? Which is the most commonly found on Earth? - Iron meteorites are composed mostly of iron and nickel. Stony-iron meteorites are a mix of silicate minerals and iron-nickel alloy. Stone meteorites are made mostly of silicate minerals. Stones are the most commonly found on Earth. Within the Stones category, what is the di_erence between chondrites and achondrites? - Chondrites are primiKve meteorites that have not undergone signiJcant heaKng or di_erenKaKon, and are composed of chondrules and other small parKcles. Achondrites are meteorites that have undergone di_erenKaKon or metamorphism, and have a more varied composiKon. What is a chondrule? How might they have formed? - A chondrule is a small, round, glassy object found in some types of primiKve meteorites. Their formaKon is sKll a topic of debate, but one theory is that they formed by melKng and solidifying in the early solar nebula. Why are scienKsts so excited about studying carbonaceous chondrites? - Carbonaceous chondrites are exciKng to scienKsts because they contain some of the most primiKve material in the solar system, including organic compounds and water. What is the di_erence between an achondrite and a primiKve achondrite? - Achondrites are meteorites that have undergone di_erenKaKon or metamorphism, and have a more varied composiKon. PrimiKve achondrites are a subgroup of achondrites that have undergone less di_erenKaKon or alteraKon than other achondrites. What are the possible sources of micro-meteoroids (a.k.a. interplanetary dust)? - Micro-meteoroids can come from comets, asteroids, and collisions between those bodies. lOMoARcPSD|32296826

How does a meteor shower occur? What is the di_erence between a meteor shower and a Jreball? - A meteor shower occurs when Earth passes through the debris leU behind by a comet or asteroid. The debris burns up in Earth's atmosphere, creaKng a series of visible meteors. A Jreball is a parKcularly bright meteor that can occur during a meteor shower or as a standalone event. How is the light of a Jreball formed? Why do the colors change? - The light of a Jreball is formed as the meteoroid's atmospheric entry heats up the air around it, creaKng a glowing plasma. The colors can change due to variaKons in the meteoroid's composiKon or atmospheric condiKons. Are meteorites hot when they land? Why or why not? - Meteorites are not typically hot when they land, as they have cooled down during their - atmospheric descent. How does the atmosphere slow a meteoroid's momentum? - The atmosphere slows a meteoroid's momentum through a combinaKon of drag, heaKng, and ablaKon. The fricKon with the atmosphere causes the meteoroid to slow down and eventually break apart. How does a meteoroid’s mass and velocity a_ect its momentum and kineKc energy? - A meteoroid's momentum and kineKc energy are directly proporKonal to its mass and velocity. The higher the mass and velocity of the meteoroid, the greater its momentum and kineKc energy. Many meteors are destroyed in the atmosphere before they reach the Earth’s surface – what kinds of meteors (size, speed) are more likely to survive? - Smaller and slower meteors are more likely to be slowed down and burn up completely in the atmosphere. Larger and faster meteors have more momentum and kineKc energy, and are more likely to survive and reach the Earth's surface. How does atmospheric fricKon a_ect the surface of the meteorite? - Atmospheric fricKon causes the surface of the meteorite to heat up and melt, which can cause the formaKon of a fusion crust. This crust is typically very thin and black, and can provide clues about the meteorite's journey through the atmosphere. Where are meteorites on Earth oUen found and why? - Meteorites on Earth are oUen found in places like deserts, where they stand out against the light-colored sand and are less likely to be obscured by vegetaKon. They can also be found on ice sheets, where they are preserved and can be more easily spo^ed. Meteorites can also be found in areas where they have been buried by sediment or incorporated into rock formaKons. What techniques do we use to analyze a meteorite? What can we learn from these tests? - ScienKsts use a variety of techniques to analyze meteorites, including microscopy, spectroscopy, X-ray di_racKon, and isotopic analysis. These tests can reveal informaKon lOMoARcPSD|32296826

about the meteorite's composiKon, age, and origin, and can help us understand more about the early history of the solar system. For example, isotopic analysis can reveal the age of the meteorite, and X-ray di_racKon can help us determine its mineral composiKon. Unit 5 intro: The gas giants: What is the deJniKon of a gas giant planet (a.k.a. Jovian planet)? - A gas giant planet, also known as a Jovian planet, is a large planet that is primarily composed of gas, such as hydrogen and helium, rather than rock or other solid materials. What are the 4 gas giants in our solar system? - The 4 gas giants in our solar system are Jupiter, Saturn, Uranus, and Neptune. What are the common features shared by the gas giants? - The gas giants share several common features, including their large size, low density, thick atmospheres, numerous moons and rings, and lack of a solid surface. How/when do the gas giants form? - Gas giants are thought to form through a process called core accreKon, in which a solid core of rock and ice gradually accumulates gas from the surrounding protoplanetary disk. This process is believed to take millions of years and likely occurred during the early stages of our solar system's formaKon. What did we learn by watching the Shoemaker-Levy 9 comet impacKng Jupiter? - By watching the Shoemaker-Levy 9 comet impact Jupiter in 1994, astronomers were able to learn more about the composiKon and structure of Jupiter's atmosphere. The impact created huge dark scars on Jupiter's surface and sent plumes of gas and debris high into the atmosphere, providing a rare opportunity to study the planet's atmospheric dynamics in detail. The impact also provided insights into the nature and frequency of impact events in the solar system. Chapter 14: Jupiter How do we know that Jupiter is big? - Jupiter's size can be determined by measuring its diameter, which can be done using telescopes. We can also measure its mass and use the relaKonship between mass and size for objects with similar composiKons. How do we know that it is hot? Why does it have a high heat ]ow (what is the internal heat engine)? - Jupiter's high temperature is due to the heat produced by its internal heat engine. The heat is generated by the planet's contracKon and by the decay of radioacKve isotopes. The planet's high heat ]ow is indicated by the strong thermal radiaKon it emits. Describe what we observe happening on Jupiter’s surface. What energy is driving the turbulence in the atmosphere? How does this di_er from how weather pa^erns are driven on Earth? What is the Great Red Spot? - Jupiter's atmosphere is characterized by strong winds and turbulence driven by the planet's internal heat and the di_erenKal rotaKon of its interior layers. The Great Red lOMoARcPSD|32296826

Spot is a persistent high-pressure region in Jupiter's atmosphere, which is created by the interacKon of di_erent atmospheric bands moving at di_erent speeds. Why did scienKsts crash the Galileo spacecraU into the surface of Jupiter? What did we learn during this descent? - The Galileo spacecraU was crashed into Jupiter to avoid contaminaKng its moons with microbes from Earth. During its descent, Galileo measured the planet's gravitaKonal and magneKc Jelds and provided valuable data on its atmosphere and composiKon. Jupiter is primarily composed of hydrogen in various states (e.g. gas, liquid etc.) Describe the structure of the planet (e.g. Fig 14.6). Does the liquid hydrogen ocean have a surface? - Jupiter's structure is characterized by a gaseous outer layer, primarily composed of hydrogen and helium, overlying a deep interior consisKng of liquid hydrogen and metallic hydrogen layers, and a rocky core. The liquid hydrogen layer does not have a well-deJned surface. Does Jupiter have a magneKc Jeld? How might it be formed? - Yes, Jupiter has a strong magneKc Jeld, which is generated by the moKon of electrically conducKng material in its interior. The magneKc Jeld is believed to be generated by a dynamo e_ect in the planet's metallic hydrogen layer. How does the magneKc Jeld interact with the solar wind and what implicaKons does this have for life (e.g. humans visiKng the planet or alien life on the moons of Jupiter)? - Jupiter's magneKc Jeld interacts with the solar wind, creaKng a large magnetosphere that can trap energeKc parKcles. This can be dangerous for spacecraU and astronauts, as well as for any potenKal life on Jupiter's moons, as the trapped parKcles can cause damage to electronic equipment and biological Kssue. Explain how the dark belts and bright zones form in Jupiter’s atmosphere. - The dark belts and bright zones in Jupiter's atmosphere are created by a combinaKon of atmospheric circulaKon and chemical reacKons. The dark belts are regions of descending gas, which contain dark-colored compounds that absorb sunlight, while the bright zones are regions of rising gas, which contain bright-colored compounds that re]ect sunlight. What are the 3 classiJcaKons of satellites (for Jupiter’s satellites and elsewhere)? Compare the characterisKcs/formaKon/orbits of each kind. - The three classiJcaKons of satellites are: - Regular satellites: Satellites that orbit in the equatorial plane of their planet and are formed from the same material as their planet. They have nearly circular orbits and are relaKvely large compared to their host planet. - Irregular satellites: Satellites that orbit in inclined, eccentric orbits and are typically small and irregularly shaped. They are thought to have been captured from the Kuiper Belt or the Oort Cloud. - Trojans: Small satellites that share the same orbit as their planet, but are located at a stable Lagrange point. What are the 3 principles in comparaKve planetology? lOMoARcPSD|32296826

- The three principles in comparaKve planetology are: (1) understanding the processes that govern the formaKon and evoluKon of planets, (2) understanding the diversity of planets within our solar system and in other star systems, and (3) using the similariKes and di_erences between planets to gain insights into the condiKons required for life. Name the 4 Galilean satellites orbiKng Jupiter: a. Callisto – ice and rock, undi_erenKated interior, li^le radioacKve heat may melt some ice, only weak magneKc Jeld b. Ganymede – silicate rock and ice, completely d i_erenKated with molten iron core, surface of ice covers a salty liquid water ocean, generates its own and magneKc Jeld. Has an oxygen-rich atmosphere. C. Europa – rock and metal, metallic core, no magneKc Jeld, temporary atmosphere formed as ice is abraded by Jupiter’s radiaKon. d. Io – iron-rich core and silicate mantle, parKally molten, temporary atmosphere from volcanic gases Compare the structure of these 4 main satellites to each other with parKcular a^enKon to how the size of the satellite and its proximity to Jupiter determine: a. If the body is di_erenKated (related to heat source, which varies among satellites) b. If there is a liquid core (and consequently a magneKc Jeld) c. If there is an atmosphere d. The density/composiKon of the satellite The structure of the 4 Galilean satellites di_ers in several ways depending on their size and proximity to Jupiter. Io is the closest to Jupiter and experiences strong Kdal forces, which results in it being the most geologically acKve satellite in the solar system. Europa is slightly further out and is thought to have a subsurface ocean of liquid water. Ganymede, being the largest moon in the solar system, has a di_erenKated interior with a molten iron core and an oxygen-rich atmosphere. Callisto is the most distant of the four and has a less di_erenKated interior, which is believed to be a mix of rock and ice. Why do Europa and Io have few craters (two di_erent reasons)? - Europa and Io have few craters for two di_erent reasons. Io's surface is constantly changing due to volcanic acKvity, so any impact craters that do form are quickly erased. On the other hand, Europa's surface is covered in a layer of ice, which is constantly being reworked by processes such as tectonics and sublimaKon, also resulKng in fewer impact craters. Which of these satellites might have some possibility of supporKng life? Why? lOMoARcPSD|32296826

- Europa has been idenKJed as having the best potenKal for supporKng life due to the presence of a subsurface ocean of liquid water, which could potenKally harbor life. AddiKonally, the presence of organic molecules has been detected on its surface. Ganymede is also thought to have a subsurface ocean of liquid water, but it is not as well-studied as Europa. Chapter 15: Saturn and Family 1. Why is it hard to view Saturn’s surface? - Saturn has a thick atmosphere with a high concentration of hydrogen and helium, which causes signi2cant light scattering and makes it discult to see the surface. Also, Saturn is quite far away from Earth, so even the largest telescopes have limited resolution. 2. How did the Cassini Huygens spacecraft get enough energy to reach Saturn’s orbit? - The Cassini Huygens spacecraft was launched in 1997 and used several gravity assists from Venus, Earth, and Jupiter to gain enough speed to reach Saturn's orbit in 2004. Once in orbit around Saturn, it used radioisotope thermoelectric generators (RTGs) to generate power. 3. Why is Saturn less dense than Jupiter? - Saturn is less dense than Jupiter because it has a smaller core and a higher proportion of hydrogen and helium gas in its outer layers, making it less compressed overall. 4. What is the interior structure of Saturn (e.g. core and various layers)? - Saturn has a rocky core that is surrounded by a layer of liquid metallic hydrogen, followed by a layer of molecular hydrogen. The outermost layer is composed of gaseous hydrogen and helium. 5. What is causing Saturn to generate heat? - The heat generated by Saturn is thought to be due to a combination of gravitational contraction and the decay of radioactive elements within the planet's core. 6. Saturn and Jupiter are similar in that there is no clear division between the atmosphere and the surface of the planet. Be sure you are aware of why this is happening. - This is because both planets have very thick atmospheres that gradually transition into denser and more compressed layers, without a clear boundary between the two. 7. What are the 2 main components of Saturn’s atmosphere? - The two main components of Saturn's atmosphere are hydrogen and helium, which together make up more than 98% of the atmosphere. 8. Explain why the atmosphere has visible belts and zones (same as on Jupiter)! - The belts and zones on Saturn's atmosphere are caused by diGerential heating and convection within the atmosphere, which leads to the lOMoARcPSD|32296826

formation of high-pressure regions (zones) and low-pressure regions (belts). 9. Explain the 3 levels of cloud formation on Jupiter and Saturn. On which planet are the clouds higher in the atmosphere and why? - The three levels of cloud formation on Jupiter and Saturn are the upper troposphere, the lower stratosphere, and the mesosphere. On Saturn, the clouds are higher in the atmosphere because the planet receives less sunlight and therefore has a colder upper atmosphere. 10. Does Saturn have a magnetic 2eld? If so, what causes it? - Yes, Saturn has a magnetic 2eld that is generated by the motion of electrically conducting materials within the planet's core. 11. Why are there “gaps” in the rings of Saturn? - The gaps in Saturn's rings are caused by the gravitational eGects of the planet's many moons, which disrupt the orbits of the ring particles and create gaps in the overall distribution. 12. What are the rings composed of? Do other gas giants have rings? Compare diGerences in formation of rings among the gas planets. - Saturn's rings are composed of billions of individual particles of water ice, ranging in size from tiny dust particles to large boulders. Other gas giants, including Jupiter, Uranus, and Neptune, also have rings, but they are generally less extensive and less bright than Saturn's. 13. Why are the rings orbiting Saturn’s equator rather than spread in a haze about the whole planet? - The rings orbiting Saturn's equator are a result of the planet's gravitational 2eld and the orbits of its many moons, which exert gravitational forces that keep the rings con2ned to a narrow band around the equator. Do we know what causes the appearance of “spokes” on the B ring? - The exact cause of the spokes on Saturn's B ring is not fully understood. However, it is believed that they are created by the interacKon between the ring parKcles and Saturn's magneKc Jeld. Do collisions of parKcles in the rings make parKcles larger or smaller? Explain. - Collisions between parKcles in Saturn's rings can result in both larger and smaller parKcles. Some parKcles can sKck together and form larger parKcles, while other collisions can break up parKcles into smaller fragments. Outline the evidence that suggests the material in Saturn’s rings is young. - The material in Saturn's rings appears to be relaKvely young based on several lines of evidence. One piece of evidence is that the rings are made up of mostly water ice, which is vulnerable to erosion and sublimaKon over Kme. Another piece of evidence is the presence of small "moonlets" in the rings, which would have been disrupted if the rings had been around for billions of years. What is the argument that suggests the rings might be old? lOMoARcPSD|32296826

- On the other hand, some researchers believe that the rings could be much older than previously thought. This argument is based on the fact that the rings are stable and do not appear to be dissipaKng, which would suggest that they have been around for a long Kme. What is a possible source of the water/ice in the rings? - One possible source of the water/ice in Saturn's rings is from the breakup of a comet or other small icy body that came too close to Saturn and was torn apart by Kdal forces. Titan has an atmosphere and conKnents making it intriguingly like Earth. Let’s compare some of their properKes: a. What is the composiKon of Titan’s atmosphere? - Titan's atmosphere is composed mainly of nitrogen (about 98%) with small amounts of methane (about 2%) and other trace gases. b. Is the surface hot or cold? -The surface of Titan is very cold, with temperatures around -180°C (-292°F). c. What is special about the volcanic acKvity on Titan? -Volcanic acKvity on Titan is special because it involves the erupKon of liquid hydrocarbons like methane and ethane instead of molten rock like on Earth. d. What is the source of methane in the atmosphere on Titan vs. Earth? - The source of methane in Titan's atmosphere is likely from the breakdown of organic molecules that have been created through the interacKon of ultraviolet light and methane in the atmosphere. On Earth, most of the methane in the atmosphere comes from natural gas deposits and other sources. e. What are Titan’s dunes composed of? -Titan's dunes are composed of organic molecules, mainly - hydrocarbons like methane and ethane. f. Does Titan have the ingredients required for life? -Titan has some of the ingredients required for life, such as organic molecules and a liquid water ocean beneath its icy surface. However, the extreme cold and lack of sunlight make it unlikely that life as we know it could exist there. Which of Saturn’s satellites looks like the Death Star from the Star Wars movies? - Mimas is the Saturnian satellite that resembles the Death Star from the Star Wars movies due to its large impact crater known as Herschel. What processes result in Enceladus having liquid water at the surface? - Enceladus has liquid water at its surface due to the presence of hydrothermal vents on the ocean ]oor beneath its icy crust. These vents release heat and minerals into the ocean, creaKng an environment that could potenKally support life. lOMoARcPSD|32296826

What is a shepherd satellite and how do they stabilize rings? - A shepherd satellite is a small moon that helps stabilize and shape the rings of a planet. They orbit in or near the rings and their gravity interacts with the parKcles in the ring, creaKng gravitaKonal forces that push and pull the parKcles, causing them to clump together or disperse. The gravitaKonal in]uence of the shepherd satellite can also create gaps in the rings, keeping the parKcles from colliding and breaking apart. Examples of shepherd satellites in the Saturn system are Prometheus and Pandora, which act to stabilize the F ring. Chapter 16: Uranus and Neptune Why are Uranus and Neptune considered “ice giants”? - Uranus and Neptune are considered “ice giants” because a signiJcant amount of their composiKon is made up of water, ammonia, and methane ice. Do these planets have rings? What might be the source of material for the rings? - Yes, both Uranus and Neptune have rings. The material for the rings is likely to come from moons that have been sha^ered by impacts from comets or asteroids. Contrast the internal heat of these two planets. Why might Uranus be cold? Where does Neptune’s heat originate? - Neptune generates more internal heat than Uranus due to its higher gravitaKonal compression and ongoing gravitaKonal interacKons with its largest moon, Triton. Uranus is cold because it has a lower internal heat ]ow and lacks a signiJcant internal energy source. Neither Uranus nor Neptune can be seen from Earth with the naked eye – Explain (in general) what theories were used to predict their locaKons. - Uranus and Neptune were both discovered through mathemaKcal predicKons based on observaKons of the gravitaKonal e_ects of these planets on other celesKal bodies, which suggested their existence and locaKon. What is unique about Uranus’s rotaKon, what caused this and how does this a_ect its seasons? - Uranus's rotaKon is unique in that it is Klted at an extreme angle of about 98 degrees, causing its axis to be almost parallel to the plane of the Solar System. This is believed to be the result of a massive collision with a planet-sized object early in its history. Uranus's extreme axial Klt causes it to experience extreme seasonal variaKons in its weather pa^erns. What is the internal structure (and composiKons of layers) of Uranus and Neptune? - Uranus and Neptune have a similar internal structure, consisKng of a rocky core surrounded by a mantle of water, ammonia, and methane ice, and an outer layer of hydrogen and helium gas. Why do Uranus and Neptune have less hydrogen and helium than Saturn and Jupiter? - Uranus and Neptune have less hydrogen and helium than Saturn and Jupiter because they formed farther from the Sun, where there was less material available to form gas giants. lOMoARcPSD|32296826

Do these planets have magneKc Jelds? What creates them? - Yes, both Uranus and Neptune have magneKc Jelds. The exact cause of these magneKc Jelds is not well understood, but they are believed to be generated by convecKve moKon within the planets' metallic hydrogen mantles. What in the atmosphere makes the planets appear blue-green? - The blue-green color of Uranus and Neptune is due to the absorpKon of red light by methane in their atmospheres, which re]ects blue and green light back to space. Uranus has a belt-zone cloud pa^ern (as also seen on Jupiter and Saturn) – we keep seeing this theme – it would be prudent to understand how/why these form. - The belt-zone cloud pa^ern on Uranus, Jupiter, and Saturn is caused by di_erences in wind speeds and cloud formaKon in the planets' atmospheres, creaKng alternaKng bands of light and dark clouds. Although Uranus and Neptune have similar atmospheres, Neptune is a bit hazy – why? - Neptune appears hazy due to the presence of methane and other hydrocarbons in its atmosphere, which sca^er light and create a smog-like haze. What is the di_erence between conducKon, convecKon and radiaKon? - ConducKon is the transfer of heat through direct contact between two materials, convecKon is the transfer of heat by the movement of ]uids, and radiaKon is the transfer of heat through electromagneKc waves. Uranus's main satellites include Oberon, Titania, Umbriel, Miranda, and Ariel. Let's consider them all together: a. What is the evidence that some of these have of being tectonically acKve? b. What is the heat source that would drive acKve tectonics? c. What makes some of these satellites dark in color? d. How well does ice preserve evidence of geological events (e.g. collisions or tectonics)? a. Some of Uranus's main satellites, such as Miranda and Ariel, have evidence of being tectonically acKve, such as faults and grooves on their surfaces. b. The heat source that drives acKve tectonics on these satellites is likely the result of Kdal heaKng, which is caused by gravitaKonal interacKons between the satellites and Uranus. c. Some of these satellites, such as Umbriel and Oberon, are dark in color due to the presence of carbonaceous material on their surfaces. d. Ice can preserve evidence of geological events, such as collisions or tectonics, for a very long Kme, as evidenced by the surface features observed on many icy bodies in the solar system. lOMoARcPSD|32296826

Triton is a satellite of Neptune: a. Why might Triton crash into Neptune? b. Triton is very cold – what element is liquid on the planet, and how does this a_ect surface features? c. Why does Triton have an atmosphere? d. What is a probable source of heat that drives acKvity on Triton? a. Triton may have been a Kuiper Belt Object that was captured by Neptune's gravity, which could have caused it to eventually crash into the planet. b. The element that is liquid on Triton is methane, which can freeze into nitrogen and methane ice on the surface. This freezing and melKng of the surface can create geysers and other interesKng features. c. Triton has an atmosphere because it is able to retain a thin layer of nitrogen and methane gas due to its weak gravity. d. The probable source of heat that drives acKvity on Triton is thought to be a combinaKon of Kdal heaKng from Neptune and radioacKve decay in its interior. Unit 6- Plutoids, TNOS, AND COMETS What is the deJniKon of a plutoid? - A plutoid is a trans-Neptunian dwarf planet, which means it is a celesKal body that orbits the sun beyond Neptune and has enough mass to assume a nearly round shape. What is the name of the plutoid that is bigger than Pluto? - The name of the plutoid that is bigger than Pluto is Eris. Comets: a. What are they made of? -Comets are made of ice, dust, and rocky material. The ice is mostly frozen water, but it can also include frozen gases like carbon dioxide, methane, and ammonia. b. Describe their orbit. Comets have highly ellipKcal orbits that take them from the outer solar system to the inner solar system. When they approach the sun, the heat causes the ice to vaporize and create a coma, a fuzzy cloud of gas and dust around the nucleus. c. Where is the orbit anchored? The orbit of a comet is anchored in the Oort Cloud, a vast region of space beyond the orbit of Neptune that is believed to be the source of many long-period comets. Short-period comets, on the other hand, are thought to originate from the Kuiper Belt, a region of the solar system beyond lOMoARcPSD|32296826

Neptune's orbit where many dwarf planets, including Pluto, are located. Chapter 17 Plutoids and TNOS What are the names of the 4 dwarf planets classiJed as plutoids? - The four dwarf planets classiJed as plutoids are Pluto, Eris, Haumea, and Makemake. Why was Pluto demoted from planet status? - Pluto was demoted from planet status due to a decision made by the InternaKonal Astronomical Union (IAU) in 2006. The IAU decided that to be considered a planet, an object must meet three criteria: it must orbit the Sun, it must be spherical in shape, and it must have cleared its orbit of other debris. Pluto was found to not meet the third criterion and was thus reclassiJed as a dwarf planet. What is a Trans-Neptunian Object? - A Trans-Neptunian Object (TNO) is any object in the Solar System that orbits the Sun at a greater average distance than Neptune. Where are the Kuiper Belt and the Oort cloud? - The Kuiper Belt is a region in the outer Solar System that extends from the orbit of Neptune to about 50 astronomical units (AU) from the Sun. The Oort Cloud is a hypothesized spherical cloud of icy objects that is thought to be the source of long- period comets and is located at the outermost reaches of the Solar System. What is the name of the spacecraU that recently passed Pluto? - The name of the spacecraU that recently passed Pluto is New Horizons. Describe the technique of blink-comparison that was used to originally Jnd Pluto - Blink-comparison is a technique used to discover new objects in space. It involves taking two photographs of the same secKon of sky and then rapidly alternaKng between them to see if any objects appear to move. This was the technique used to originally Jnd Pluto in 1930. What is Planet X? - Planet X is a hypotheKcal planet that is thought to exist beyond the orbit of Neptune. It has not yet been observed directly but is hypothesized to explain certain orbital anomalies of other objects in the outer Solar System. Is Pluto always farther from the Sun than Neptune? Why or why not? - No, Pluto is not always farther from the Sun than Neptune. Pluto has a highly ellipKcal orbit that can bring it closer to the Sun than Neptune for certain periods of Kme. What 4 kinds of ice on found on Pluto’s surface? - The four kinds of ice found on Pluto's surface are nitrogen ice, methane ice, carbon monoxide ice, and water ice. Why is Pluto’s surface not heavily cratered? - Pluto's surface is not heavily cratered because its icy surface is constantly being renewed through processes such as sublimaKon, which is the transiKon from a solid directly to a gas. lOMoARcPSD|32296826

Does Pluto have an atmosphere? How is it created? - Yes, Pluto has a thin atmosphere that is created through the sublimaKon of ices on its surface, primarily nitrogen. What is the structure of Pluto’s interior (as far as we can tell right now)? - As far as we can tell right now, Pluto's interior is likely di_erenKated, with a rocky core surrounded by a mantle of water ice and other ices. Is Charon a satellite of Pluto? Explain your answer. - Yes, Charon is a satellite of Pluto. It is considered to be a moon of Pluto and is the largest of its Jve known moons. On both Pluto and Charon, water is so cold that it behaves like rock. - Water on Pluto and Charon is so cold that it exists in a solid state, similar to rock. Why is there almost no methane on Charon, while Pluto has lots? - Methane is present on Pluto's surface because it can be trapped in its nitrogen ice, but Charon does not have a thick atmosphere or a signiJcant nitrogen ice layer. This means that methane, which is highly volaKle, escapes from Charon's surface into space. What is the main kind of ice on Charon? - The main kind of ice on Charon is water ice, which covers most of its surface. There are also traces of other ices, such as ammonia and methane, in some areas. Does Pluto have satellites? - Yes, Pluto has Jve known satellites: Charon, Nix, Hydra, Kerberos, and Styx. Charon is the largest and the only one discovered before the 21st century. What do we know about the composiKon of Eris? - Eris is a dwarf planet located in the Kuiper Belt. Its composiKon is similar to Pluto's, with a rocky core surrounded by a mantle of water ice and frozen gases such as methane and nitrogen. What is the Sca^ered Disc? - The Sca^ered Disc is a region of the outer solar system that extends from the Kuiper Belt to the innermost region of the Oort Cloud. It is populated by small icy objects that were ejected from their original orbits by the giant planets during the early history of the solar system. These objects have highly ellipKcal and inclined orbits, and some of them can cross the orbit of Neptune. Chapter 18: comets What are comets? - Comets are small, icy objects that orbit the sun. They are composed of rock, dust, ice, and frozen gases and can have highly ellipKcal orbits. Where do they come from? - Comets are thought to come from two main regions of the outer solar system: the Kuiper Belt and the Oort Cloud. What are they made of? lOMoARcPSD|32296826

- Comets are made of rock, dust, ice, and frozen gases such as water, methane, and ammonia. What do comets represent? - Comets represent the leUover building blocks of the solar system's formaKon and can provide informaKon about the condiKons that existed in the early solar system. As well as possibly being the main source of water to the inner planets, they may also have been the source of many of life’s basic building blocks (amino acids parKcularly). Why would life not be able to survive on a comet? - Life would not be able to survive on a comet because they lack the necessary condiKons for life to exist, such as a stable atmosphere, a suitable temperature range, and a source of energy. What are the 4 parts of a comet, what are they composed of, and how do they form? - The four parts of a comet are the nucleus, coma, hydrogen cloud, and tails. The nucleus is composed of rock, dust, and ice and is the solid core of the comet. The coma is a cloud of gas and dust that forms around the nucleus as it is heated by the sun. The hydrogen cloud is a layer of gas that surrounds the coma and re]ects sunlight. The tails are made of gas and dust parKcles that are blown away from the coma by the solar wind. How are comets related to meteor showers? - Meteor showers occur when the Earth passes through the debris leU behind by a comet as it orbits the sun. Which direcKon does each of the tails point? - The ion tail of a comet points directly away from the sun, while the dust tail curves away from the ion tail due to the pressure of sunlight. What is the di_erence between long-period and short-period comets? - Long-period comets have orbits that take them more than 200 years to complete, while short-period comets have orbits that take them less than 200 years to complete. Why are the lives of short-period (acKve) comets limited? - The lives of short-period comets are limited because each Kme they pass close to the sun, some of their ice and dust is vaporized, causing them to lose mass over Kme. What is the typical life span of a short-period comet? - The typical lifespan of a short-period comet is a few tens of thousands of years. Where in our solar system are comets formed? Are they old or young? - Comets are formed in the outer solar system, in the Kuiper Belt and the Oort Cloud. They are thought to be some of the oldest objects in the solar system, daKng back to its formaKon 4.6 billion years ago. What is the Kuiper belt? How did it form? - The Kuiper Belt is a region of the outer solar system beyond Neptune that is populated by icy objects. It is thought to have formed from the leUover material from the solar system's formaKon. For what two reasons is the Kuiper belt signiJcant for the study of the solar system? lOMoARcPSD|32296826

- The Kuiper Belt is signiJcant for the study of the solar system because it contains many small bodies that are thought to be prisKne remnants of the early solar system and because it is the source of many short-period comets. How do icy Trans-Neptunian Objects become comets? (2 ways) – How do we tell which process created individual comets? - Icy Trans-Neptunian Objects can become comets in two ways. The Jrst is through a gravitaKonal perturbaKon, such as a close encounter with a planet, that causes the object's orbit to be altered and sends it towards the inner solar system. The second is through the sublimaKon of volaKle materials, such as water ice, as the object gets closer to the Sun and warms up. We can tell which process created individual comets by studying their orbits and the composiKon of their material. What is the Oort cloud? How did it form? - The Oort cloud is a hypotheKcal, spherical cloud of icy objects that is believed to surround our solar system at a distance of about 50,000 to 100,000 astronomical units (AU) from the Sun. It is named aUer Dutch astronomer Jan Oort, who Jrst proposed its existence in 1950. The Oort cloud is thought to have formed early in the history of our solar system, as a result of the gravitaKonal in]uence of the giant planets, and to contain billions of icy objects. Based on their orbits, how do we know that long-period comets come from the Oort cloud? - Long-period comets have highly eccentric orbits that take them far out of the plane of the solar system, and they approach the Sun from all direcKons. This suggests that they come from a distant, isotropic reservoir of objects like the Oort cloud, which is thought to surround the solar system at a great distance. What is Comet Halley coated with? What is at the surface of Comet Borrelly? - Comet Halley is coated with a dark, organic-rich material that forms a crust on the surface. This material is thought to have been formed by the breakdown of more complex organic molecules that were present in the comet's nucleus. The surface of Comet Borrelly, on the other hand, is covered with dark, carbon-rich dust parKcles that have been eroded from the comet's nucleus by sublimaKon and other processes. Have we ever collected material from a comet? What material did they Jnd? - Yes, we have collected material from a comet. In 2004, NASA's Stardust mission ]ew by Comet Wild 2 and collected dust parKcles from the comet's coma using a special collector made of aerogel. The samples were returned to Earth in 2006, and analysis revealed that they contained a variety of minerals and organic compounds, including amino acids, the building blocks of life. Can comets carry viruses? lOMoARcPSD|32296826

- There is currently no evidence to suggest that comets can carry viruses or other biological organisms. However, comets do contain organic molecules, including amino acids, which are the building blocks of life, and some scienKsts have suggested that comets could have played a role in the origin of life on Earth. Why has Halley’s comet one of the most well-known comets by humans? - Halley's Comet is one of the most well-known comets because it is a bright and easily observable comet that has been observed by humans for thousands of years. It is also a short-period comet, with an orbit that brings it back to the inner solar system every 76 years, which means that it has been seen by many generaKons of people throughout history. 23.Can you see comets with the naked eye? Yes, some comets are visible with the naked eye. The brightness and visibility of a comet depend on various factors, such as its distance from the Sun and Earth, its size, and the amount of gas and dust it is releasing. Some famous comets that were visible with the naked eye in the past include Halley's Comet, Comet Hale-Bopp, and Comet McNaught. Unit 7 Intro: 1. The six possible places we hope to 2nd evidence of life in our solar system other than Earth are:  Mars  Europa (one of Jupiter's moons)  Enceladus (one of Saturn's moons)  Titan (another of Saturn's moons)  Ganymede (another of Jupiter's moons)  Triton (one of Neptune's moons) 2. Life, as we know it, requires a few key things to develop, including liquid water, an energy source, and organic molecules. Scientists also believe that a stable environment, such as a protective atmosphere and a stable temperature range, is essential for life to thrive. Additionally, the presence of key chemical elements like carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur is necessary for the formation of complex organic molecules that are the building blocks of life. Chapter 19: Q1. Why does living ma^er need energy? A1. Living ma^er requires energy to carry out metabolic processes such as growth, repair, movement, and reproducKon. Q2. What is the simplest life form we are aware of? A2. The simplest known life form is a single-celled organism called a prokaryote, such as a bacterium. lOMoARcPSD|32296826

Q3. Is a virus a life form? Why or why not? A3. The classiJcaKon of viruses as a life form is debated among scienKsts. Some consider them non-living because they cannot replicate on their own and do not have a cellular structure, while others consider them living because they can reproduce with the help of a host cell. Q4. What is a cell? What are nucleic acids composed of? A4. A cell is the basic unit of life, and nucleic acids, such as DNA and RNA, are composed of nucleoKdes. Q5. What is the role of DNA? RNA? A5. DNA contains geneKc informaKon and serves as the blueprint for the synthesis of RNA, which in turn directs the synthesis of proteins. Q6. Why is life on Earth (and probably elsewhere) carbon-based instead of silicon-based? A6. Carbon is more versaKle than silicon in forming a variety of complex organic molecules, and it can bond with other elements in many di_erent ways, making it a more suitable basis for life. Q7. Describe how the process of natural selecKon results in the evoluKon of species. A7. Natural selecKon is the process by which organisms with advantageous traits are more likely to survive and reproduce, passing on those traits to their o_spring and eventually leading to the evoluKon of new species. Q8. What is our deJniKon for “Life”? A8. Life is typically deJned as a characterisKc of organisms that exhibit growth, reproducKon, adaptaKon, and response to sKmuli. Q9. What was the Miller-Urey experiment? What did they create (and how)? What was the signiJcance? A9. The Miller-Urey experiment simulated condiKons thought to be present on early Earth, producing amino acids and other organic compounds from inorganic precursors. This experiment provided evidence that the building blocks of life could arise from non-living ma^er. Q10. What evidence of life has been found (or claimed to have been found) in meteorites? A10. Some meteorites contain organic molecules and microscopic structures resembling fossilized bacteria, although these claims are controversial and not widely accepted. Q11. What is the primordial soup? A11. The primordial soup is a hypotheKcal mixture of organic molecules and water thought to have existed on early Earth, providing a possible environment for the formaKon of life. Q12. How/where might amino acids link together to form larger molecules? lOMoARcPSD|32296826

A12. Amino acids can link together through a process called pepKde bond formaKon, forming polypepKdes and eventually proteins. Q13. How old are Earth’s oldest fossils? A13. Earth's oldest fossils are around 3.5 billion years old. Q14. Stromatolites, some of the earliest complex organisms, produced oxygen which was toxic to them – how did they survive? Is this process sKll happening today? A14. Stromatolites survived by using oxygen as an energy source, eventually evolving into more complex organisms. This process is sKll occurring today in certain environments, such as some shallow marine environments. Q15. What is the di_erence between a prokaryote and a eukaryote? A15. Prokaryotes are single-celled organisms without a nucleus or membrane-bound organelles, while eukaryotes have a nucleus and other membrane-bound organelles. Q- Why do we need ozone? How did life survive before there was enough oxygen in the atmosphere to create ozone? A- Ozone is important because it absorbs most of the Sun's harmful ultraviolet radiaKon, which can damage or kill living organisms. Before the atmosphere had enough oxygen to create ozone, life forms may have survived by living in environments that were protected from the Sun's harmful radiaKon, such as deep in the ocean or underground. Q- What is the Cambrian explosion and when did it happen? A- The Cambrian explosion was a relaKvely brief period in Earth's history (around 541 million years ago) when there was a rapid diversiJcaKon of life forms, including the appearance of most major animal groups. It is considered a major event in the history of life on Earth. Q- When looking for life elsewhere in the solar system or universe why do we look for liquid water? A- Liquid water is considered a key ingredient for life as we know it, so scienKsts look for environments with liquid water (or the potenKal for liquid water) as a possible indicaKon of habitability. Q- What condiKons prevent life on the planet in the inner solar system (terrestrial planets) versus the outer solar system (gas giants)? A- The inner solar system planets (Mercury, Venus, Earth, Mars) are too hot or too cold for life as we know it, while the gas giants (Jupiter, Saturn, Uranus, Neptune) are composed mostly of gas and do not have a solid surface or the necessary condiKons for life. Q- What are the arguments for/against life on the satellites Europa, Ganymede and Titan? A- The moons Europa and Ganymede are considered potenKally habitable because they have subsurface oceans of liquid water and geologic acKvity that could provide energy for life. Titan, on the other hand, has a thick atmosphere of methane and other hydrocarbons, which is not conducive to life as we know it. lOMoARcPSD|32296826

Q- Why were scienKsts excited to see methane on Mars? A- Methane is a potenKal biosignature, meaning it could be produced by living organisms. So, the detecKon of methane on Mars raised the possibility of life on the planet. Q- Was/is there liquid water on Mars? A- Yes, there is evidence that liquid water exists on Mars, but it is not always stable or easily accessible. Q- Under what condiKons is it possible that life on Mars and Earth would be similar? A- Life on Mars and Earth could be similar if they evolved under similar environmental condiKons, such as the presence of liquid water and similar atmospheric composiKon. Q- When looking for planets outside of our solar system that might have life, what characterisKcs do scienKsts look for? What is the goldilocks zone? A- ScienKsts look for planets that are in the "habitable zone" or "goldilocks zone," which is the range of distances from a star where condiKons may be suitable for liquid water to exist on the planet's surface. They also look for planets with a similar size and composiKon to Earth. Q- Why is it unlikely to Jnd planets with life orbiKng: a. Binary stars b. Large stars c. Small stars? A- Binary stars are unlikely to have stable habitable zones because of gravitaKonal interacKons, and life on planets around large stars may be a_ected by high levels of radiaKon or intense stellar acKvity. Planets around small stars may be habitable, but they may be Kdally locked, which could make it dizcult for life to thrive. Q-26. Astronomers have been searching for other planets that might have the right characterisKcs for life – have they found many potenKal candidates? A- Yes, astronomers have found many potenKal candidates for planets that might support life. The Kepler spacecraU alone idenKJed over 4,000 potenKal exoplanet candidates, and future missions like the James Webb Space Telescope are expected to discover even more. Q-27. What are the drawbacks of communicaKon with other planetary systems by radio waves? A- One major drawback of communicaKon with other planetary systems by radio waves is the vast distances involved. Even with our most powerful radio telescopes, signals would take many years to travel between stars, making real-Kme conversaKon impossible. AddiKonally, radio signals are subject to interference and degradaKon as they travel through space, further complicaKng communicaKon e_orts. Q-28. What are the 3 common characterisKcs of a mass exKncKon on Earth? A- The three common characterisKcs of a mass exKncKon on Earth are a rapid decline in the diversity and abundance of species, a widespread geographic distribuKon of the exKncKon event, and evidence of ecological and environmental disrupKon. Q-29. By the end of this chapter you should have a good idea of the physical properKes of planets that might support life, but also pay a^enKon to the Kme factor – how long did it take for life to evolve on Earth? What about intelligent life? Given that planets can move out of the lOMoARcPSD|32296826

goldilocks zone or that all life can be wiped out by an exKncKon event, Jnding intelligent life elsewhere will be dizcult. A- Life on Earth is believed to have originated around 3.5 to 4 billion years ago, and it took several billion more years for complex mulKcellular life to evolve. The evoluKon of intelligent life on Earth is a much more recent development, with Homo sapiens appearing only around 200,000 years ago. Given the vast distances involved in interstellar travel and the many potenKal hazards facing life on other planets, Jnding intelligent life elsewhere in the universe may be a daunKng challenge. lOMoARcPSD|32296826