Final Exam Astronomy

9) Why are Saturn's colors more subdued than Jupiter?

Its clouds lie deeper in its atmosphere.

Suggest how you might turn on and turn off the terrestrial magnetic fields.

Slow the rotation of the planet to a very slow rate, cool the core so that hot liquid metal can no longer drive convection.

1) Why are extrasolar planets hard to detect directly?

A Sun-like star is about a billion times brighter than the sunlight reflected from its planets, and trying to see it at that distance is like being in San Francisco and trying to see a pinhead 15 meters from a grapefruit in Washington, D. C.

16) In general, how can we tell a dead comet nucleus from an asteroid? Describe two ways.

A dead comet nucleus would have a crust over dirty ice. The orbits are different- most comets have very elongated orbits while asteroids have more circular orbits.

What is a magnetosphere? Describe its role in protecting any atmosphere from the solar wind and in creating auroras.

A magnetosphere is created by a magnetic field and act like a protective bubble surrounding the planet defecting most solar wind particles. It prevents harmful particles from entering our atmosphere but the ones that make it in become trapped charged particles in the magnetosphere and which can gain enough energy to follow the magnetic field down to earth's atmosphere where they collide with atmospheric atoms and molecules causing them to radiate the light of the aurora.

23) What is a meteor? About how big is the object that produces the average meteor?

A meteor is a flash of light caused when a particle from space burns up in our atmosphere. The vast majority of particle that make meteors are no larger than peas.

Choose at least three major geological features of Venus and explain how we think each one formed.

Aphrodite terra- tectonic forces fractured and twisted the crust. Coronae- mantle convection beneath the lithosphere caused the coronae to be pushed upward by hot plumes of rock in the mantle. Stratovolcanoes- formed by thick lava into round blobs.

17) Describe why comets have tails. Why do most comets have two distinct visible tails, and why do the tails go in different directions? Why is the third, invisible tail of small pebbles of interest to us on Earth?

As the coma grows due to the comet furthering into the inner solar system, tails form as an extension of the coma. The plasma tail is made up of ionized gas and plasma that escapes from the coma, then ionized by UV light and carried straight away from the sun by solar wind; points outward from sun. The dust tail is not affected by the solar wind and instead is pushed away by the much wasker pressure of sunlight itself (radiation pressure); the tail generally points away from the sun but has a slight curve back in the direction the comet came from. The third tail is what usually causes meteor showers on Earth; this is why they generally reoccur at the same time each year.

1) Briefly describe the general characteristics of asteroids-including sizes, masses, densities, and compositions.

Asteroids come in a wide range of sizes with the largest being Ceres, just under 1000 kilometers across, all the way down to small potato sized objects. They have varying masses and densities, which can provide insight to the composition. Asteroids are made mostly of rock and metal.

What do we mean by atmospheric pressure? Why does pressure decrease with altitude? What is 1 bar of pressure?

Atmospheric Pressure: Collisions of molecules in all directions. Farther down, more air pressing down, heavier pressure. 1 bar is 14. 7 pounds per square inch.

Why does large planets retain internal heat longer than smaller planets?

Because larger planets have more insolation, taking much longer for interior heat to reach the surface.

10) How are the planets around pulsars been detected? How are they formed?

Because the intrinsic rotation of a pulsar is so regular, slight anomalies in the timing of its observedradio pulses can be used to track the pulsar's motion. Like an ordinary star, a pulsar will move in its own small orbit if it has a planet. Calculations based on pulse-timing observations can then reveal the parameters of that orbit. After a supernova material accreted into planets around the pulsar.

3) Explain why a planet can cause its star to move slightly in the sky.

Both planets and stars orbit around a center of mass and the planets exert gravitational tugs on the star, these motions allow us to detect planet-orbiting stars.

What is the carbon dioxide cycle, and why is it so crucial to life on Earth?

Carbon dioxide cycle is the mechanism by which Earth self regulates its temperature. This is crucial because it allows Earth to maintain a livable temperature

3) How does the largest asteroid compare in size to the planets? How does the total mass of all asteroids compare to the mass of a terrestrial world?

Ceres, the largest asteroid is a little less than 1000 kilometers in diameter, about a quarter of the diameter of the moon. The total mass of all asteroids would create a sphere with a diameter less than 2000 kilometers in diameter, just over half the diameter of our moon.

What is the greenhouse effect? Describe how it warms a planet. Look at this and tell how changing, CO2 levels, H2O levels and cloud cover changes the temperature of the planet.

Certain air molecules absorb infrared better. These include water vapor (H2O), Carbon Dioxide (CO2), and methane (CH4). Thus, when they absorb infrared, they heat up, and heat up atmosphere. Increasing CO2 and H2O levels increase the temperature where as increasing cloud cover decreases the temperature.

13) What does a comet look like when it is far from the Sun? How does its appearance change when it is near the Sun? What happens to comets that make many passes near the Sun?

Comets are just balls of ice and rock without the shimmering tail when far from the sun; when comets come close to the sun they are heated and grow the tails that allow us to see them. Comets that pass near the sun many times do not have very long life spans in relation to our solar system. Comets lose ice every time they pass around the sun and dust can accumulate on the surface preventing the escape of interior gas. This can lead to the comet coming apart or disintegrating.

How do we think that Mars lost atmospheric gas? What basic planetary property (size, distance from the Sun, or rotation rate) would have had to be different for Mars to have retained a thicker atmosphere?

Convection raised gas and the weak magnetic field (weakened as the small planet cooled and core convection ceased) allowed for solar wind particles to strip the atmosphere into space. Size.

Summarize the processes by which planetary interiors cool off.

Convection- the energy transfer process in which warm materials expand and rise while cooler materials contract and sink. Conduction- the process by which thermal energy is transferred by direct contact from warm material to cooler material. Radiation- emitted thermal radiation carries energy away from the planet and cools it.

8) How do the cloud layers help explain Jupiter's colors?

Different types of clouds reflect different types of light. Jupiter's water clouds reflect white light and the mid-layer clouds reflect brown and red light.

What is differentiation, and how did it lead to the core- mantle- crust structures of the terrestrial worlds?

Differentiation is the process in which gravity separates materials according to density, high density sinks, low density rises. This resulted in layers made of different materials based on their density forming the core, mantle, and crust structures.

Why does Earth have both a solid and liquid core? What is the physics involved?

Differentiation- More dense materials are pulled to the center by gravity forcing less dense materials upward.

5) How does the Doppler technique work? Explain how it can tell us a planet's orbital period, orbital distance, and orbital eccentricity.

Doppler method uses to Doppler affect to measure changes in the stars velocity toward or away from us. Showing a blueshift when moving towards us and a redshift when moving away, so alternating shifts tells us there's orbital motion around a center of mass. The period of the stars motion is the planet's orbital period, therefore we know the approximant orbital distance. Any asymmetry in the Doppler curve tells us that the planet is moving with varying speed and therefore must have a more eccentric elliptical orbit.

Briefly summarize the geological history of the Moon. How did the lunar maria form?

Due to the Moons small size, it may have lost its internal heat leaving it without any volcanoes or tectonics to cover the craters. The small size contributes to the lack of atmospheres and erosion. The weak gravity inhibits the Moon form holding gas for long periods, and without ongoing volcanoes, it lacks outgassing needed to replenish gas lost in the past. Lunar maria- smooth dark regions on the Moon's surface (look like oceans when see form afar); Due to the heat released by the decay of radioactive elements in the Moon's interiror, lava floods came. Molten rock then welled up through the cracks of the moon's lithosphere, flooding the largest impact craters with lava.

24) Explain how meteor showers are linked to comets. Why do meteor showers recur at about the same time each year?

The third tail is what usually causes meteor showers on Earth; this is why they generally reoccur at the same time each year. Earth passes through the trail at the same points in its orbit.

30) Briefly explain why icy moons can have active geology at much smaller sizes than rocky worlds.

Each tiny impact of the small moons, tiny particles from small moon's surface, and these released particles become new, dust-size ring particles. Larger impacts shatter a small moon completely, creating a supply of boulder-size ring particles.

35) Explain why we think that ring particles must be replenished over time. Will the jovian planet rings always look the same?

Each tiny impact of the small moons, tiny particles from small moon's surface, and these released particles become new, dust-size ring particles. Larger impacts shatter a small moon completely, creating a supply of boulder-size ring particles. NO.

Why does Earth have a global magnetic field? Why don't the other terrestrial worlds have similarly strong magnetic fields?

Earth has an interior region of electrically conductive fluid or gas, convection occurs in that layer, and Earth has a moderately fast rotation. The moon has no convection and slow rotation, venus has slow rotation, Mar's core doesn't have enough heat to drive convection, Mercury has a measurable field due to a little liquid in its core.

Describe several ways in which Earth's atmosphere is unique among the terrestrial worlds, and how each unique feature is important to our existence.

Earth retained most of its outgassed water; enough to form vast oceans. Earth has very low levels of carbon dioxide in its atmosphere caused by the presence of oceans, which dissolved the carbon dioxide. Allows for our breathable atmosphere and water. Composed primarily of nitrogen and oxygen. Allowing for life.

Describe the interiors of the five terrestrial objects and tell why there is a difference.

Earth- rocky crust, mantle metal core, thin lithosphere of crust and part of mantle. Moon- lithosphere extends to the crust, core is a more normal size. Mercury- Lithosphere extends to the core, core is relatively large. Venus- Similar to Earth, core appears to be slightly larger. Mars- Huge Lithosphere, almost all the way to the core. Different sizes causing different rates of cooling off also cooling off may have started earlier.

What might account for the lack of plate tectonics on Venus? How did Earth and Venus get to be so different geologically?

Either it has weaker mantle convection or that its lithosphere resisted fracturing because it is thicker and stronger. Venus's high surface temperature could account for ridding the planet of water causing the lithosphere to thicken and strengthen. Lack of plate tectonic activity and high surface temperature.

21) What is Eris? How is it related to Pluto?

Eris is a Kuiper belt object that is 27% larger than pluto and currently lies about twice as far as Pluto from the sun. Eris and Pluto are tied for the largest Kuiper belt objects and both qualify as dwarf planets because they are big enough to be round but have not cleared their orbital neighborhoods, and are both comets of roughly the same size.

24) What is Enceladus doing to create the E ring?

Erupting geysers on the surface caused the formation of the E ring.

19) Scientists strongly suspect that Europa has a subsurface ocean, even though we cannot see through the surface ice. Briefly explain why scientists think the ocean exists.

Europa is suspected to have a subsurface ocean because it only has a handful of craters and close up photos of the surface combined with the fact that Europa has enough heat to melt subsurface ice into liquid water.

9) Why are newly formed planets easier to image?

Formations energy causes them to have a large infrared signature to image.

Describe Earth's basic atmospheric structure, from the ground up. How do interactions of sunlight and gases explain the existence of each of the atmospheric layers?

Four basic layers, the troposphere, the stratosphere, the thermosphere, and the exosphere. Most visible light reaches the ground and warms the surface, infrared light is absorbed by greenhouse gases in the troposphere which is why temperature drops with altitude in the troposphere. Stratosphere are density is too low to absorb greenhouse gases, heating is achieved by the absorption of UV light by ozone making temperature increase with altitude. X- rays are easily absorbed and therefore are absorbed in the thermosphere and cause temperatures to be very high. Gas particles move quiet quickly in the exosphere but because of extreme low density collisions are very rare.

Summarize the process by which planetary interiors get hot.

Heat of Accretion- Accretion deposits energy brought in from afar by colliding planetesimals. Heat from Differentiation- Gravitational potential energy is converted to kinetic energy by the friction generated by the shifting materials. Heat from radioactive decay- Rock and metal contained radioactive isotopes and when their nuclei decay, subatomic particles fly off and collide with neighboring atoms causing some mass energy to transfer to the thermal energy of the planet.

15) What do we mean by a hot Jupiter? How should we expect a hot Jupiter to compare to the real planet Jupiter?

Hot Jupiter refers to planets that have a Jupiter like mass but a much higher surface temperature

25) What is Iapetus' strange equatorial ridge and how do we explain it?

Iapetus is a chain of 10-kilometer high mountains girdling the moons equator. Scientists believe that the ridge was formed at an earlier time when Iapetus rotated much faster than it does today or it is made of material left over from the collapse of a ring.

Define each of the four geologic processes and give examples of features shaped by each process.

Impact cratering- the creation of bowl shaped impact craters by striking asteroids and comets. Volcanism- the eruption of molten rock or lava from a planets interior on to its surface. Tectonics- The disruption of a planets surface due to internal stresses. Erosion- the wearing down or building up of geological features by wind, water, ice, and other weather phenomena.

Why does convection occur in the troposphere, leading to active weather, but not in the stratosphere?

In the dense troposphere layer hot are rises and cold air falls and because the temperature drops with altitude this causes a convection movement, which is the primary cause of storms. Convection only occurs when there is strong heating from below and since the stratosphere air density is so low IR light from below can pass right through causing very little heat from below.

18) What are the key features of Jupiter's four Galilean moons? Explain the role of tidal heating and orbital resonances in shaping these features.

Io is extremely volcanic and for that reason has no impact craters. Europa's surface is covered by water ice and is heavily fractured with very little impact craters. Ganymede is the largest moon in the solar system, with a surface of water ice that is either dark and heavily cratered or light-colored with very few craters. Callisto is the outermost Galilean planet and a heavily cratered ice ball and my hide a subsurface ocean. Tidal heating is the force from Jupiter that causes the moon to keep the same face towards Jupiter, but Jupiter's mass causes a very strong tidal force and causes Io to continuously flex in different directions generating friction and heat. Orbital resonance affects all the Galilean moons and is the orbital periods falling into a simple mathematical relationship and causes orbits to be slightly elliptical.

22) Describe the atmosphere of Titan. What did the Cassini/Huygens mission learn about Titan's surface?

It is so thick it hides the surface from view. 90% molecular nitrogen (N2 ) and argon, methane, ehtane and other hydro compounds. River Valleys merging together, flowing down to what looks like a shoreline.Surface has a hard crust but is a bit squishy below, like sand with liquid mixed in and also ice boulders rounded by erosion - indicates a wet climate.

11) How would the appearance of Neptune change if you moved it to the same distance from the Sun as Jupiter?

It would have way less of a blue color do to methane not having cold enough temperatures to condense creating the blue color and because a smog like haze, created from gases interacting with UV light, would scatter sunlight before it could reach clouds.

5) What accounts for the different densities of the asteroids Itokawa and Vesta?

Itokawa is a rubble pile, meaning that it is not a monolithic object. Instead it is made up of many objects that have coalesced under the influence of gravity and they have much lower densities because there are large cavities between various chunks that make them up. Vesta is a solid object.

Briefly describe how differences in composition among the Jovian planets can be traced to their formation.

Jupiter and Saturn are made up mostly of hydrogen and helium and their ice rich planetesimals making up 3% for Jupiter and 10% for Saturn. Uranus and Neptune are made up of hydrogen compounds, rock and metal, and hydrogen and helium. Their icy planetesimals make up for about a third of their total mass. This difference in the amount of gas the planets captured is probably due to their different distances from the sun. Solid particles that condensed farther from the sun would have been more spread out meaning it would have taken longer for the to accrete into large planetesimals.

16) Describe the consequences of the Jovian planets magnetic fields.

Jupiter has a large magnetic field and can cause auroras near the planets poles and cause damage to orbiting spacecraft. Charged particles also bombard the surfaces of Jupiter's moons altering their surface materials and even creating a thin atmosphere.

5) Why does Jupiter have so much internal heat? What generates internal heat on other Jovian planets?

Jupiter has so much internal heat because it is most likely still slowly contracting which would convert gravitational potential energy into thermal energy providing an ongoing internal source of heat, in addition to remaining heat of accretion and radioactive decay. Saturn's heat comes from helium condensing into liquid at high levels in the interior and rains down in the lower interior representing ongoing differentiation. Uranus emits virtually no excess internal energy. Neptune emits two times as much energy as it receives from the sun and is believed to still be contracting.

Briefly describe the interior structure of Jupiter and why it is layered in this way. How do the interiors of the other Jovian planets compare to Jupiter?

Jupiter is made up of distinct layers that do not differ in composition much; except for the core they are all mostly hydrogen and helium. They do however differ in phase: cloud tops, gaseous hydrogen, liquid hydrogen, metallic hydrogen, core. Saturns interior is very similar to Jupiter but contains a smaller layer of metallic hydrogen. Uranus and Neptune however have no liquid or metallic hydrogen layer and instead have a cloud top, gaseous hydrogen, and then hydrogen compound layer.

6) Briefly describe Jupiter's atmospheric structure and cloud layers. Describe this.

Jupiter's thermosphere consists of very low-density gas heated to about 1000 K by solar x-rays and energetic particles in the magnetosphere. The stratosphere is where UV light is absorbed creates a smog like haze that masks the colors below. The troposphere is where the thick cloud cover on Jupiter is located due to various substances condensing at different temperatures. There is a cloud layer that is cold enough for water to condense and form clouds (-100km), then cold enough for ammonium hydrosulfide to form clouds (-50km), then ammonia condenses.

Name four consequences of not having an atmosphere on the moon and how lack of an atmosphere brings them about.

Lack of an atmosphere allows for sandblasting of the surface by micrometeorites from space. Lack of an atmosphere prevents erosion from occurring therefore the suface of the moon is relatively unchanged. Heavily cratered due to the atmosphere not preventing objects from impacting the surface and not erasing the craters. Heat was released much more quickly and gases escaped from the moon.

What do we mean by the lithosphere? How does lithospheric thickness vary among the five terrestrial worlds?

Lithosphere is the relatively rigid outer layer of a planet generally encompassing the crust and uppermost portion of the mantle. Thickness is related to size, smaller planets have thicker lithospheres, Earth and Venus have thin ones.

What is the structure of the moon's core?

Made up of a mantle, a partially melted area, a fluid outer core, and a solid inner core.

21) Look up the densities of Jupiter's four Galilean moons in Appendix E.3, and notice that they follow a trend with distance from Jupiter. Based on what you've learned about condensation in the solar nebula, can you suggest a reason for this trend among the Galilean moons? Next, compare the densities of the moons with the planetary densities in Table E.1. Based on the comparison, do you think it was as hot toward the center of the nebula surrounding Jupiter as it was at the center of the solar nebula? Explain.

Mass and density decline with distance from Jupiter probably because accretion would have drawn heavier more dense particles closer to the planet. It colder because it was outside the frostline.

12) What data suggest that many extrasolar planets are similar in nature to the Jovian planets of our solar system?

Mass measurements and densities tell us that they are like jupiter and other jovian planets.

14) About how many exoplanets are like Neptune?

There are around 1,457 Neptune sized planets. But many exoplanets are more like Jupiter and Saturn.

Briefly summarize the atmospheric properties of the five terrestrial worlds. How do they differ in surface temperature, pressure, and composition?

Mercury- composed of helium, sodium, and oxygen. Pressure is 10^-14 bar. Day temp is 425 C and night is -175 C Venus- composed of mainly carbon dioxide then nitrogen. Pressure is 90 bars. Temp is 470 C. Sulfuric acid clouds. Earth- composed of nitrogen, oxygen, argon, water, and carbon dioxide. Pressure is 1 bar. Average surface temp is 15 C. Water clouds and pollution. Moon- composed of helium, sodium, and argon. Pressure is 10^-14 bar. Day temp is 125 C and night at -175 C. No atmosphere. Mars- composed of carbon dioxide, nitrogen, and argon. Pressure is .007 bars. Temp is -50 C. Water and carbon dioxide clouds and dust.

briefly summarize the different geological appearances of the five terrestrial worlds.

Mercury- heavily crated, long steep cliffs Venus- very few craters, twin peaked volcano Earth- Oceans and landmasses Moon- heavily cratered, geologically dead Mars- Impact craters, and dry river beds

11) What is the difference between a meteor and a meteorite? How can we distinguish a meteorite from a terrestrial rock?

Meteors are only the flash of light caused by a particle entering our atmosphere at high speeds. Meteorites are rocks that are large enough to survive the fall through the atmosphere and end up on the surface. Meteorites are often covered with dark, pitted crust; some have unusually high metal content (enough to attract a magnet), and often contain elements that are not common on Earth.

Why are Uranus and Neptune Blue?

Methane gas in the upper atmospheres absorb red light allowing only blue light to penetrate to the level at which the methane clouds exist.

10) How do meteorites get from the moon and Mars to the Earth? How do we know they come from the Moon or Mars?

Moderately large impacts can blast surface material from terrestrial worlds into interplanetary space and once blasted into space the rocks orbit the sun until they come crashing down to another world. We know they come from mars and the moon because careful analysis of the meteorite's composition matches that of the moon and mars instead of that of asteroids.

Briefly summarize the geological history of Mercury. How are Mercury's great cliffs thought to have formed?

Most of its volcanic and tectonic activity ceased within 1 to 2 billion years after it formed. Volcanism erased many of mercury's impact craters. Mercury's great cliffs are thought to have formed by tectonic forces compressing the crust causing the surface to crumble. Because crumpling would have shrunk the portions of the surface it affected. Mercury gained and retained more internal heat from accretion and differentiation causing the core to swell, as the core cooled it contracted so did the mantle and lithosphere generating tectonic stresses that created the great cliffs.

22) What does Neptune do to the orbits of the Kuiper Belt Objects?

Neptune keeps objects in resonance, anything that orbits twice for Neptunes threes times causes resonance and gravitationally links up objects.

Suppose we could magically give Mercury the same atmosphere as Earth. Assuming this magical intervention happened only once, would Mercury be able to keep its new atmosphere? Explain.

No, the light intensity would cause a runaway greenhouse affect to occur and rid the planet of much of its atmosphere.

8) How many extrasolar planets been detected directly? Explain.

Only a few planets have been found using direct detection. This is because the glare from stars makes direct detection of planets extremely difficult, especially given how close together the stars and planets lie when observed from Earth.

11) Summarize the planetary properties we can in principle measure with current techniques, and state which techniques allow us to measure each of these properties.

Orbital periods and distance- astronomic method, Doppler method, and transit method, then using Newton's version of Kepler's third law we can determine orbital distance. Orbital eccentricity and inclination- Doppler method, precise measurements of orbital inclinations require systems with multi- planet transits but in the future combining astronomic, transit, and Doppler data should allow us to determine precise orbital inclinations. Planetary mass- astronomic and Doppler methods. Planetary size- Transit method. Planetary density- can only be found through knowing a planet's size from the transit method and its mass from the Doppler method. Atmospheric composition and temperature- Transit and eclipses.

8) Briefly explain how orbital resonances with Jupiter have affected the asteroid belt.

Orbital resonance occurring because of Jupiter prevented any planets sized objects from forming in the material rich region, and instead over 4.5 billion years ongoing orbital disruptions prevented these pieces from accreting.

What is outgassing and why is it so important to our existence?

Outgassing is the process of releasing gases from a planetary interior, usually through volcanic eruptions. All the gases that make up the atmosphere and water vapor that rained down was released by outgassing.

Describe each process by which atmospheres gain or lose gas. What factors control thermal escape? Which loss processes are permanent? Which are temporary?

Outgassing, evaporation/sublimation, and surface ejection cause gaining gas. Condensation, chemical reactions, solar wind stripping, and thermal escape cause losing- gases. Thermal escape is controlled by the planet's size, distance from the sun, and atmospheric composition. Solar wind stripping and thermal escape are permanent. The others are temporary.

What is ozone? How does the absence of ozone on Venus and Mars explain why these planets lack a stratosphere?

Ozone is an inorganic molecule OO2 that is exceptional at absorbing UV light. The lack of oxygen in the atmosphere of other terrestrial worlds means that they also lack ozone and therefore lack a stratosphere.

9) What are Potentially Hazardous Asteroids and why are they important? About how many are there?

PHAs are a subset of a larger group of near- Earth asteroids that have the closest orbits to Earth's, coming within 5 million miles, and big enough to survive passing through Earth's atmosphere and cause damage on a regional or greater scale. They are important to know about because the provide opportunities for human and robotic exploration and because they are potentially hazardous to Earth. There are roughly 4,700 PHAs plus or minus 1,500.

17) Many extrasolar Jovian planets have high orbital eccentricities. How might they have ended up with such eccentric orbits?

Planetary migration causes eccentric orbits and when two planets have close encounters the planets dance then get tossed causing very eccentric orbits.

16) Many extrasolar Jovian planets orbit surprisingly close to their stars. How might they have ended up in these orbits? How do we think hot Jupiters formed? Why didn't one form in our solar system?

Planetary migration, hot jupiter's formed outside the frostline and migrated inward due to gravity interacting with particles. Saturn got locked into a resonance with jupiter and pulled it back out.

If there were no greenhouse effect, what factors would determine a planet's surface temperature? How do the "no greenhouse" temperatures of the terrestrial planets compare to their actual temperatures, and why?

Planets distance from the sun, and the planets overall reflectivity, Because the greenhouse effect increases heat in the atmosphere the no greenhouse temperatures on planets are lower.

20) Briefly describe Pluto and Charon. Why won't Pluto collide with Neptune? How do we think Charon formed?

Pluto is one of the largest bodies in the Kuiper belt, considered a dwarf planet, and has a thin atmosphere of nitrogen and other gases formed by vaporization of surface ices. Charon is Pluto's largest moon and is closer in distance and relative size to its parent planet than our moon is to Earth and was thought to have formed from a giant impact similar to the one that created Earth's moon. Neptune orbits the sun precisely three times for every two Pluto orbits and this stable orbital resonance means that Neptune is always a safe distance away whenever Pluto approaches its orbit.

For the terrestrial objects how does the pressure and temperature change from surface to center?

Pressure and temperature increase as you move from surface to center. Crust, mantle, core

12) Distinguish between primitive meteorites and processed meteorites in terms of both composition and origin.

Primitive meteorites are the first type to be formed and originate with the birth of our solar system and are unchanged since they first accreted in the solar nebula. They are composed of rocky minerals, small fractions of metal flakes, and in some cases substantial amounts of carbon compounds, and sometimes water. Processed meteorites were once larger objects that processed the original material of the solar nebula into another form. They are composed of both high-density iron and nickel with smaller amounts of other metals (resembling terrestrial cores) or have lower densities and are made with rock that resembles that of terrestrial mantles and crusts.

34) What are propeller moons and what are they doing?

Propeller moons are moons located within the rings, gravity changes orbits around gap moons causing a ripple in front and behind the propeller moon.

What is regolith?

Regolith is a layer of loose, heterogenous material covering solid rock. Includes dust, soil, broken rock, and other materials and is present on Earth, Moon, Mars, some asteroids and other terrestrial planets and moons.

26) What is the difference between a regular satellite and an irregular satellite?

Regular satellites have small circular orbits and low inclinations and probably formed around the time of Jupiter's formation. Irregular satellites have large orbits, inclinations, and eccentricities and are believed to be objects captured by Jupiter during its formation.

33) Briefly describe the effects of gap moons and orbital resonances on ring systems.

Ring particles are nudged by the gravity from larger and more distant moons or from small moons located within the gaps (gap moons); this creates a gap in the rings. Moons further away cause periodic nudges that reinforce one another and cause a gap in the rings. This reinforcement due to repeated gravitational tugs is an example of orbital resonance.

32) Explain the different brightness's of rings.

Rings look bright when they contain enough particles (ice) to intercept sunlight and scatter it back towards us. We see gaps in places where fewer particles are present.

Briefly summarize the evidence linking human activity to global warming. What are its potential consequences?

Rising concentration of greenhouse gases caused by humans could expediently raise the overall temperature of Earth. The burning of fossil fuels and other human activities are clearly increasing greenhouse gases provide by finding enriched molecules of CO2 carrying the distinct ratio of isotopes present in fossil fuels. Climate modules that ignore human activity fail to match the observable rise in global temperatures.

What do we mean by a runaway greenhouse effect? Explain why this process occurred on Venus but not on Earth

Runaway greenhouse affect is a positive feedback cycle in which heating caused by the greenhouse affect causes more greenhouse gases to enter the atmosphere, which further enhances the greenhouse affect. A greater intensity of light on Venus caused by its closer distance to the sun caused this affect and is why earth has not suffered from it.

31) What are planetary rings made of, and how do they differ among the four jovian planets?

Saturn's rings are made of countless tiny ice particles ranging in size from dust grains to boulders. The rings of Jupiter, Uranus, and Neptune are much fainter, they are made of significantly fewer particles and the particles are generally darker and smaller.

29) Suppose that Jupiter had never existed. Describe at least three ways in which our solar system would different, and clearly explain why.

There would be no asteroid ring due to the lack of orbital resonance that jupiter provided, jovian planets would be larger because Jupiter would not have accreted all the material before it reached the other planets, and there would be more terrestrial planets and possibly larger ones because Jupiter's migration would not have destroyed planetesimals.

Briefly explain how each of the following geological features of Earth is formed: seafloors, continents, islands, mountain ranges, rift valleys, and faults.

Seafloors are formed through a process called subduction, seafloor crust meets continental crust and is forced under. Continents where formed over billions of years by volcanism, stresses associated with plate tectonics, and erosion. Islands where formed by ocean volcanoes building up material until it reached the surface also through seafloor plates carrying the less dense volcanoes towards other low density patches and the patches sticking together. Mountain ranges form when material from the mantle push surface rock higher and through collisions of continent bearing plates pushing land upwards. Rift valleys are created from continental plates pulling and cause the crust to thin. Faults are formed when plates slip sideways relative to each other causing fractures in the lithosphere.

What causes seasons? How and why do seasons on Mars differ from seasons on Earth? [This is review]

Seasons are caused by the tilt in a planet's axis. Because of greater axis tilt and high variation in distance from the sun Mars experiences more extreme seasonal changes.

2) How do we measure an asteroid sizes, masses, densities, and compositions?

Sending spacecraft to visit the asteroid. Careful measurements of brightness can provide insight on size, since it depends on the objects size, distance, and reflectivity. Comparing the visible and infrared brightness tells us the proportions of incoming sunlight that an asteroid reflects and absorbs, knowing these proportions the asteroids brightness and distance tell us its size. Spectroscopy can tell us an asteroid's composition. Observing an the gravitational affect that an asteroid has on a passing spacecraft or on a tiny orbiting moon and using Newton's version of Kepler's third law can tell us the asteroid's mass. Once an asteroids mass and size is known we can calculate its density.

17) Briefly describe how we categorize jovian moons by size. What is the origin of most of the medium-size and large moons? What is the origin of many of the small moons?

Small moons less than 300 kilometers, medium moons from 300 to 1500 kilometers and large moons more than 1500 kilometers in diameter. Most formed by accretion within the disks of gas surrounding individual Jovian planets (always keep the same face towards their planet) Most are captured asteroids or comets.

Why do the Moon and Mercury have so little atmospheric gas? How is it possible that they might nonetheless have water ice in polar craters?

Small size lets gas escape. Comets may have crashed and embedded ice into the planets.

Describe each of the four factors that can lead to long-term climate change.

Solar Brightening: The sun has grown gradually brighter with time, increasing the amount of solar energy reaching the planets. Changes in tilt Axis: Tilt may change over long time. Changes in reflectivity: Decreases/ increases amount of sunlight absorbed. Changes in greenhouse gas abundance: More= hotter, less= cooler.

12) Briefly describe Jupiter's weather patterns. What is the Great Red Spot?

Strong winds and powerful storms They have (white bands) zones and (darker bands) belts It is a giant storm more than twice as wide as all of planet Earth

Describe the conveyor-like action of plate tectonics on Earth. How does this action explain the differences between seafloor crust and continental crust?

Subduction occurs at ocean trenches, where dense seafloor crust pushes under the less dense continental crust, thereby returning seafloor crust to the mantle. The subductiong seafloor crust may partially melt, with low-density material melting first and erupting from volcanoes as new continental crust. Seafloor crust is created by eruptions at mid ocean ridges where plates spread apart. This explains the differences between the crusts because seafloor crust is constantly being remade.

13) What is a super-Earth and how do we know they exist? Are any in the habitable zone of their star?

Super- earths are terrestrial planets that masses that are considerably larger than Earth's mass. We know they exist because of prior discoveries of planets that are 4 to 5 times larger in mass than Earth. About 8 terrestrial planets that are between one and two times the size of Earth orbit their suns in the habitable zone. Kepler has detected them.

2) What are 6 methods used to detect extrasolar planets. Which have discovered the most planets thus far?

The Astrometric method, the Doppler method, the transit method, Direct detection, Pulsar, Indirect gravity, micro lensing.

6) Why does the Doppler technique generally allow us to determine only minimum planetary masses rather than actual planetary masses? Should we expect these minimum masses to be close to the actual masses? Explain.

The Doppler technique generally only allows us to determine minimum planetary masses because planets who's orbit is perpendicular to the plane of the orbit does not cause a Doppler shift in the spectrum of its star. Therefore planetary masses that we infer from the Doppler method will be accurate only for planets in edge on orbits, otherwise the true orbital speed and mass of the planet is underestimated.

13) Based on the infrared and visible images, is Jupiter's Great Red Spot warmer or cooler than nearby clouds? Is it is higher or lower in altitude than the nearby clouds? Explain.

The Great Red Spot is colder than surrounding red band clouds and is higher in altitude than red bands but lower in altitude than white bands.

Why are these temperature profiles different?

These temperature profiles are different because of the different gases and layers of atmosphere that the planets atmospheres posses. Venus, Earth, and Mars all have tropospheres and thermospheres but only Earth has middle atmosphere heating to make a stratosphere.

18) Describe the Kuiper belt and Oort cloud in terms of their locations and the orbits of comets within them. How did comets come to exist in these two regions?

The Kuiper belt extends from about 30-50 AUs and comets orbit in the same plane and direction as the planets. The Oort cloud extends out to about 50,000 AU and comet orbits have random tilts and eccentricities. Comets ended up in the Oort cloud because leftover planetesimals that where in the space between Jupiter and Neptune where flung off in all directions by the gravity of planets and ended up on orbits with very large average distances from the sun. The Kuiper belt comets came to be because planetesimals beyond Neptune where much less likely to be cast off by gravitational encounters and instead remained in orbits going in the same direction of the planets and concentrated relatively near the ecliptic plane.

Why is the moon so much more heavily cratered than Earth?

The Moon's surface has gone on almost unchanged for billions of years, while the surface of Earth has very few craters meaning that it has a younger surface, where erosion and volcanism most likely covered craters.

7) Where is the asteroid belt located, and why?

The asteroid belt is located between the orbits of Mars and Jupiter. The asteroid belt is located here due to orbital resonance. If an asteroid were to exist somewhere outside of where the asteroid belt was located, it would face many "tugs" as the asteroid passed by Jupiter. These tugs eventually pull all the asteroids into the location where they face the fewest amount of pulls from Jupiter, and asteroids that have orbital periods that are 1/4,1/3, 2/5, 3/7, and 1/2 of Jupiter's 12 year cycle, will quickly be pulled into a different orbit.

4) How does the astrometric technique work? Why hasn't it been very successful in discovering extrasolar planets to date?

The astronomic method uses precise measurements of stellar positions to look for the sight motion caused by orbiting planets. It hasn't been successful because the farther away a star is the smaller its side to side motion appears and for a planet of any mass, a greater orbital distance means a larger astronomic effect on its star, but is also takes longer to measure the effect

14) Suppose the Jovian planets' atmospheres were composed only of hydrogen and helium, with no hydrogen compounds at all. How would the atmospheres be different in terms of clouds, color, and weather? Explain.

The atmospheres would have no color variation and very little weather due to the homologous make up and lack of convection and condensation. Hydrogen and helium clouds would exist but there would be no color.

Why isn't liquid water stable on Mars today, and why do we nonetheless think it flowed on Mars in the distant past?

The atmospheric pressure is too low today for liquid water to occur on the surface of mars; we believe that it flowed in the past due to the erosion patterns that it left behind.

14) What produces the coma of a comet?

The coma of a comet is produced by the comet passing by the sun, accelerating and increasing in surface temperature causing ices to vaporize into gas that escapes the comet's gravity and drags away dust particles from the nucleus creating a huge dusty atmosphere.

15) What is the comet nucleus and what does it look like? How does that appearance change?

The comet nucleus is the central chunk of ice of the comet. They are darker than charcoal due to rocky and carbon rich material that is mixed in with the ice. The appearance can change in that the nucleus can shrink in size due to passing around the sun and can become covered in dust making the comet appear as an asteroid.

26) Briefly describe the evidence suggesting that an impact caused the mass extinction that killed off the dinosaurs. How might the impact have led to the mass extinction?

The discovery of sediment spread in a layer throughout earth from about 65 million years ago that is unusually rich in iridium, a rare metal on Earth because it sunk to the core during differentiation, supports a hypothesis that a giant asteroid impacted Earth and wiped out the dinosaurs. This would have caused an impact winter, a greenhouse crisis, atmospheric pollution, global wild fires, tsunami effects, and acidification of the normally slightly alkaline waters of the ocean.

15) Why does Jupiter have such a strong magnetic field? Describe a few features of Jupiter's magnetosphere and compare it to the magnetospheres of the other Jovian planets.

The global magnetic field and Jupiter's rapid rotation. It traps far more charged particles than Earth's - Io contributes many additional particles. They create auroras and belts of intense radiation. The other Jovian planets have much weaker magnetic fields and magnetosphere.

Why is Jupiter so much denser than Saturn? Could a planet be smaller in size than Jupiter but greater in mass?

The immense mass compresses its interior, due to its large force of gravity, to a much higher density. Jupiter is as big as a Jovian planet can get because adding gas to Jupiter would cause its weight to compress the interior enough to make the planet smaller instead of bigger.

25) Briefly describe the impact of Comet Shoemaker-Levy 9 on Jupiter.

The impact of comet SL9 on Jupiter was observed and each individual nucleus hit the planet with the force of a million hydrogen bombs. Comet nuclei barely a kilometer across left scars large enough to swallow Earth and the scars lasted for months before the winds of Jupiter swept them from view.

Explain how crater counts tell us the age of a surface.

The more craters on a surface the older it is.

Why is the Sky blue? Why are sunrises and sunsets red?

The sky is blue because visible light consists of all colors of the rainbow but not all the colors are scattered equally. Gas molecules scatter blues light much more effectively and they reach our eyes from all directions. At sunrise and sunset the sunlight must past through a greater amount of atmosphere causing most of the blue light to be scattered away leaving only red light.

28) Why are the four Galilean satellites and Titan and Triton so much different? Compare their interiors and atmospheres.

They all interact with the planet they orbit differently causing differences in interior heat and therefore leading to atmospheric differences. Titan has a thick atmosphere and is a moon whose geology is run by ice. Ganymede, Europa, and Callisto are all icy planets with liquid water oceans possibly residing under the ice. Io is extremely volcanically active. Titan has a substantial atmosphere. All have rocky cores and gain heat by flexing a solid (resonance).

Why are some spherical?

They are big enough to where gravity forces them into a spherical shape.

7) How do the structures and clouds differ on the other Jovian planets? Describe this.

They are very similar with differences mainly caused by varying distances from the sun leading to planets having their cloud layers at different altitudes. Water on Saturn condenses in the lower atmosphere because of the warmer temperatures at a lower altitude and Neptune and Uranus are so cold that any cloud layers similar to those on Jupiter and Saturn would be too deep in their atmospheres to see.

19) How may resonances be important in affecting extrasolar planet orbits? How are these effects similar to the effects of resonances in our solar system, and how are they different?

Things like to stay in resonance and cause objects to be gravitationally coupled and hold each other in place and stabilize and circularize orbits like in our solar system (low eccentricity and circular orbits). Gravity clumps up debry in the list an the planet is drawn in and most stuff goes into the star and the planet becomes stuck. large objects can also pull or push planets.

This table shows that Venus's surface temperature in the absence of the greenhouse effect is lower than Earth's, even though Venus is closer to the Sun. Explain this unexpected result in one or two sentences.

This is due to the fact that Venus suffered from runaway greenhouse effects that caused the majority of the temperature gain on the planet. Earth on the other hand does not rely on the greenhouse affect as much to attain its temperature.

23) What is Titan's atmosphere like? How does Titan manage to have erosion?

Titan's atmosphere is so thick that it blocks the surface from view except at a few wavelengths of light and is about 90% molecular nitrogen, then argon, methane, ethane, and other hydrogen compounds. Methane and ethane rain causes erosion since it is far to cold for liquid water on the surface. It has an atmosphere because there is low loss and outgassing stays ahead.

27) Why do we think Triton is a captured moon?

Triton is believed to have been captured; it orbits Neptune backwards and at a high inclination to Neptune's equator.

20) How could we explore the ocean on Europa? Why might that not be such a good idea for Ganymede?

Using a tiny submarine that is no larger than two soda cans, this may not be such a good idea on Ganymede because the ocean would lie at least 150 kilometers under the surface.

Choose five features on a global map of Mars and explain the nature and likely origin of each.

Valles Marineris- a huge system of valleys on mars created by tectonic stresses Tharsis Bulge- created by a long-lived plume of rising mantle material that bulged the surface upward and provided the molten rock for the eruptions that built the great volcanoes. Hellas Basin- created by an enormous asteroid impact. The eroded rims of large impact craters and the lack of small craters shows that there was erosion through rainfall. River delta deposits formed by the running of water through craters and other rock formations.

What evidence tells us that Venus was repaved about 750 million years ago?

Venus's relatively few impact craters are distributed uniformly throughout the entire planet, suggesting that the surface is about the same age everywhere, and the crater counts suggest a surface that is about 750 million years old.

4) Compare the number and nature of craters on Vesta, Eros, and Itokawa and explain the differences. Explain the long grooves.

Vesta has very little cratering but long grooves that could be stretch marks from impacts and surface expansion. Eros has little puddle craters. Itokawa doesn't have craters, it has boulders, Impacts were not hard enough to cause craters.

Summarize the ways in which a terrestrial world's size, distance from the sun, and rotation rate each affect its relative level of impact cratering, volcanism, tectonics, and erosion.

Volcanism and tectonics- both require internal heat, which means they depend on a planets size, larger planets have more heat. Erosion- Is based on planetary size and requires an atmosphere (outgassing), distance from the sun as well because of its role in temperature, rotation rate is important because that is the primary driver of winds and weather. Impact cratering- Size is the primary factor, larger worlds have more volcanism and tectonics that cover up craters.

Describe Earth's global wind patterns and the role of circulation cells. How does rotation affect these cells?

Warm airflows towards poles, cool air flows toward equator. Rotation causes air to turn in opposite direction with the Coriolis effect.

27) How often should we expect impacts of various sizes on Earth? How serious a threat do we face from these impacts?

We should expect impacts of various sizes every tens of millions of years apart on average. Smaller impacts would be more frequent than larger ones but they would not destroy civilization, they could kill thousands or millions of people however if they hit cities. Nearly 9000 asteroids have orbits that put them near Earth although none will impact in the foreseeable future.

7) How does the transit technique work? Could we use this method to find planets around all stars that have them? Why or why not?

When a planet's tilt is aligned with the direction to Earth we can detect the planets transit in front of the star because its light will appear temporarily dimmer. Not necessarily because the planet most pass between our line of sight and its star, something that happens about one out of a hundred times.

As the Sun gradually brightens in the future, how can the CO2 cycle respond to reduce the warming effect? Which parts of the cycle will be affected? Is this an example of positive or negative feedback?

When things get warm the oceans would dissolve more carbon dioxide compensating by cooling stuff down. This would eventually increase the temperatures of the oceans; negative feedback.

18) Based on current data, does it seem likely that our solar system has a particularly unusual layout? Explain.

Yes, considering that there is a large concentration of Jupiter and Saturn like planets as well as hot Jupiters being discovered compared to planets similar to Earth, Neptune, and Uranus.

Is there any atmosphere at the orbital altitude of the Space Station above Earth? Explain.

Yes, it's just extremely thin. Earths atmosphere extends for nearly 100 km.

29) Is there a chance for life in the Jovian systems?

Yes, life could exist in the oceans that my lay beneath the icy surfaces of some Jovian moons.

6) Can an asteroid have rings?

Yes, recently researchers observed two icy rings around the centaur Chariklo. Centaurs are part asteroid and part comet. This is extremely unusual because it is thought that only very massive objects had enough gravity to have rings orbit them.