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Chapter 8
1. What is the nebular theory? The detailed theory that describes how our solar system formed from a cloud of interstellar
gas and dust (book), the nebular theory holds that our solar system formed out of a nebula which collapsed under its own
gravity (notes) What observational evidence is there for it? We observe stars in the process of forming today; they are
always found within interstellar clouds of gas.
2. Why was it important that the initial nebula was rotating? Because it explains planets rotations, the shape of some
planets, and the shape of our solar system (like a disk)
3. As the nebula falls inward and its radius decreases, explain what happens in terms of conservation of energy and
momentum? As the cloud shrank, its gravitational potential energy was converted to the kinetic energy f individual gas
particles falling inward. These particles crashed into one another, converting the kinetic energy of their inward fall to
the random motions of thermal energy. The sun formed in the center where temperatures where the highest. Why does
the nebula heat up as it collapses? See the first answer.
4. How does the nebular theory account for the patterns of motion that we see in the solar system? The sun formed in the
center of the nebula; temperature and density where high enough for nuclear fusion reaction to begin.
The planets formed in the rest of the disk
This would explain the following:
All planets lie along one plane (in a disk)
All planets orbit in one direction
The sun rotates the same direction
The planets rotate in the same direction
Moons orbit in this direction
Most planetary orbits are near circular
5. How does the nebular theory deal with exceptions? There are more leftover planetesimals than we see today. Most of
them collided with the newly formed planets and moons during the first few 100 years of the solar system. We call this
time the time of heavy bombardment.
6. The first 100 million years of the solar system’s development is called the period of heavy bombardment.
7. What is the most likely scenario for the formation of the Moon? That a giant impact happened and a large piece and
other pieces rotated around the earth and eventually formed into our moon today.
8. Why are their two types of planets according to the nebular theory? Terrestrial and Jovian. What is the most important
physical parameter in determining how a planet will turn out, i.e., a terrestrial or a Jovian? Terrestrial formed closer to
the sun and are made of more metal and rock and are smaller planets. The Jovian plants formed further away from the
sun and formed form mini-nebulas and they are rich in gasses because of this.
9. What and where is the frost line? The boundary in the solar nebula beyond which ices could condense; only metals and
rocks could condense within the frost line…between the orbits of Mars and Jupiter
10. Why do planetary seeds grow larger past the frost line? Yes, that is why most of the planets past the frost line are so
large.
11. Why can hydrogen and helium bind to the planetary seed in the regions where the Jovians formed? Because some of
those ices, and planets gravitational pulls were so strong they could pull in those gasses.
12. How do we interpret the existence of comets and asteroids? By the existence of more planetesimals, we can see them
with our telescopes and we can see the evidence of them on the moon and such from their collisions.
13. How do you determine how old a rock is? By radiometric dating- it is comparing the amount of radioactive substances to
the amount of its decay product.
14. Do the oldest rocks on Earth accurately give the age of the Solar system? No Why? Because Earth is younger than our
solar system is and was ones all molten rock.
15. How old are the oldest rocks on Earth that are not meteoritic in origin?
16. What rocks are better indications of the age of the solar system?
17. How old is our Solar system? About 4.6 billion years
18. Do we have any clues about what triggered the collapse of our Solar system?
Chapter 9
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What is geology? The science that deals with the history of earth and its life especially as recorded in rocks. (notes)
the study of surface features (on a moon, planet or asteroid) and the processes that create them.
How do we know the structure of the interior of Earth? Because all planets start off the same, a ball of uniform
composition. Crust, mantle, core….caused by the separation of denser materials due to gravity aka differentiation.
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What is differentiation in planetary geology? The process in which gravity separates materials according to density,
with high-density materials sinking and low-density materials rising. Is the interior of the Earth uniform in
composition or differentiated? Its differentiated. It has 3 layers.
What are the layers and their phase (solid or liquid) of the interior of Earth? , Inner core solid Outer Core-liquid,
mantle-thick liquid? Crust-solid How do we know that there is liquid metal inside Earth? Because of how planets
form and because we have a magnetic field. And because of volcanoes.
What must happen to a planet in order for differentiation to occur? The entire planet must at one time been
completely melted.
What are sources of internal heat for a planet? Accretion, differentiation, radioactive decay
About how hot is the inner core of Earth? 4000-8000 degrees Kelvin
Which terrestrials have magnetic fields? Earth has a fairly strong field, Mercury has a weak field, and the moon,
Mars and Venus had no fields. Which terrestrial has the strongest magnetic field? Earth
Where does Earth’s field emanate from? From the liquid outer core. How is it produced? Electric changes in motion
via convection in the molten iron ore and the planet spinning results in a huge electromagnet.
Has Earth’s Magnetic field ever switched polarity? Yes, 9 times in the last 35 million years, last reversal was about
30,000 years ago.
What are the four basic processes that shape surface geology? Impact cratering, volcanism, tectonics, and erosion.
Describe the surface features of the terrestrial worlds (planets and Earth’s Moon). Mercury- heavily cratered, has
long steep cliffs, it has a very large core, less craters that moon, not as deep either because of stronger gravity.
Evidence of ice at North Pole. Venus- very thick cloudy atmosphere, smoother with many volcanoes and domes of
lava, very active with volcanoes and tectonics, very hot planet, heavy pressure, sulfuric acid rain and frequent
volcanic eruptions. Earth-most geologically active, volcanoes and tectonics, moderate atmosphere, H2O exists in
liquid state, few craters, and has life. The Moon- highlands has more craters and is older, mare younger with fewer
craters and dark looking, formation of Maria which was once molten lava oceans and seas. Mars- small impact
craters, thin atmosphere, no plate tectonics, evidence of water erosion, Olympus Mons: largest volcano in the solar
system, has a rotation and tilt like earth so its has seasons too, has so much frozen water at south pole that if it was
melted it would cover the planet in water 36 ft deep.
Considering the Moon:
 What are maria and how were they formed? They were old seas of lava and they eventually cooled and they
look dark now with very few craters. Highlands? They are the other higher parts of the moon that have lots of
crater impacts on it. Which is older? The highlands Why? Because of all the cratering and the heavy
bombardment period was a period that was longer ago.
 Which of the four basic processes affect the surface geology today? Impact cratering
Considering Mercury,
 Tectonics caused what unique surface feature? The large cliffs
 Is there weather? no
 Is there ice? Yes Where? North pole
Considering Mars: What is (are)
 Olympus Mons? A huge volcano, the largest one in the solar system
 The Marineris Valley? Canyon on Mars that 4,500 km long and 200 km wide
 Evidence for liquid water in the past? Yes, eroded streams and lake evidences
 Evidence for short term liquid water today? No, the temperature is too low and so is the pressure.
 The polar caps made of? What did Mars Express find out about the south cap? That there is a huge ice cap, it is
so large that if it were to melt that it would cover the planet in 36 ft deep water.
 What are Spirit and Opportunity, and what have they found out? They were rovers; they found outcrops covered
in sulfate salt minerals which is evidence that the rock had been drenched in salty water. Also found images of
rippled bedding patters in rock which are characteristic of rock sediment forming in flowing water.
 When was Mars wet and warm? 2-3 billion years ago
 Can liquid water exist for a long term there today? No Why? Because it is too cold and there is not enough
pressure Can ice? yes Where do we believe it is? All over the planet, at least 1 km deep in the surface and a
huge concentration at the south pole. Is there evidence for recent water erosion? I guess, but how recent is
recent?
Considering Venus:
 What is the current mission to Venus? Venus Express
 How do we “see” the surface of Venus? Through radar
 What space craft radar mapped its surface? mariner
 What surface features are present? Volcanoes and lava domes. Are there volcanic surface features? yes
 What types of volcanic features are present? All the volcanoes
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Describe the crater distribution. It is very even throughout the entire planet Why is the crater distribution
significant? Because it tells us the age of the planet, it is a big mystery
 What appears to have happened to Venus about a billion years ago? That it was all molten
Considering Earth:
 What is the driving force behind plate tectonics? I don’t get the question
 What other planets have plate tectonics? Venus
 Describe the geological processes active on Earth today. Impact cratering, volcanism, tectonics, and erosion.
Which planets are geologically active today? Earth and Venus Why? Mainly because of the tectonics and volcanism,
they make the biggest difference.
Why is size of the planet and distance from the Sun important? Because it has something to do with the cooling
affect (I think)
Chapter 10
1. On a microscopic level how is air pressure created? Collisions of individual atoms or molecules in an atmosphere create
pressure that pushes in all directions.
2. Why is the sky blue? Because that is the color our atmosphere reflects Sunset red? Same, but when the sun is setting
Clouds white? Because they reflect all colors, combo of all light is white.
3. What is the greenhouse effect and how does it affect the average temperature of the terrestrials? Some sun light is
reflected by the clouds, atmosphere, or planetary surface. Some reaches the surface and is absorbed warming the surface.
The warm surface then gives off thermal emission radiation in the infrared. The greenhouse effect is the absorption of
this infrared radiation from the planet’s surface by greenhouse gases in the atmosphere. What are the greenhouse
gasses? Carbon dioxide, water vapor or methane.
4. Which terrestrial planet has the highest reflectivity? Venus. Why? Because is has a high concentration of greenhouse
gases in its atmosphere and they are reflective to sunlight.
5. How would the planets be different without the green house effect? It would cause the planets to be colder and change
their atmosphere. What would be the surface temperature of Earth without greenhouse gasses? The temperature would
go way down and possibly not keep life on Earth.
6. How important is the effect on Mars, Venus, and Earth? Mars, not important. Venus, it causes the temperature to be
extremely hot. Earth, it causes the temperature to be having human life and keep it that way. What is the temperature
increase caused by the greenhouse effect on each? Mars, 6 C. Venus, 510 C. Earth, 31 C.
7. Of the terrestrials, which has the most substantial atmosphere? Earth. The least? All the rest, Mercury, Mars and the
moon are too cold, and Venus is way too hot. What is the composition of the atmosphere of each? The Moon and
Mercury, not much of anything. Venus, CO2, H2O, and N2, 90 times thicker than Earth’s and mainly CO2 remains.
Earth, CO2, H2O, and N2. Mars, CO2, H2O, N2.
8. Venus is further from the sun than Mercury, yet it is hotter. Why? Because it has so much greenhouse gases and it
absorbs solar radiation which makes it hotter.
9. What are the layers of the atmosphere? Troposphere, stratosphere, thermosphere, exosphere. As you ascend in altitude,
how do you determine which layer you are in? By the change in temperature. What layer (or layers) absorbs and is thus
heated by X-rays? Thermosphere. UV? Stratosphere. Infrared from the surface? Troposphere.
10. In Earth’s atmosphere what important gas absorbs UV? Ozone. In what layer does this occur? Stratosphere.
11. In what layer of the atmosphere does convection and weather occur? Troposphere
12. What causes auroras? The sun ejecting a stream of charged particles called the solar wind-it is mostly electrons,
protons, and He nuclei. Are there auroras on other planets? Yes. Are there auroras on Venus? yes Jupiter? Not sure
13. What is the Coriolis Effect? the apparent deflection of objects from a straight path if the objects are viewed from a
rotating frame of reference.
How does it affect the global wind patterns?
14. Know atmospheric structure, magnetosphere and aurora, and causes of long term climatic change to the level of detail
discussed in class. Here are a few example questions:
Describe the temperature profile in the troposphere, and stratosphere. Troposphere, gets colder and you increase in
height. Stratosphere, will actually get warmer as you go up, and eventually start getting colder. Where does convection
occur? Not sure
Is the Sun’s brightness changing? Don’t think so
What is the Milankovitch Theory deal with? Ice ages, because of the changes in the Earth’s tilt.
How and where are aurora created? by dancing lights in the sky caused by charged particles entering our atmosphere.
They are located at the poles.
15. Know the climate histories of the terrestrials to the level of detail discussed in class!
16. Know global warming to the level of detail discussed in class!
Chapter 11
1. Why did the Jovians form so different from the terrestrials? I think its because they were so far out in the solar system
and more gases were available for their compositions.
2. What are their bulk compositions? Hydrogen and helium for Jupiter and Saturn, and Neptune and Pluto have more
Methane. Densities? Can’t really tell what the book is saying.
3. What are the rotation rates of the Jovians? Jupiter, 9.8 hrs. Saturn, 10.6 hrs. Uranus, 17 hrs. Neptune, 16 hrs.
4. What does the oblate shape of Jupiter which results from the competition of gravity and rotation reveal about the
planet’s interior? Gravity pulls material inward, and the spinning flings material outward. Like squishing a beachball.
5. What is the temperature, pressure, and composition of the layers of Jupiter’s interior? 10% to the center: 2000K, 500,000
bars, Liquid hydrogen. 20% to the center: 5000K, 2 million bars, metallic hydrogen. 60,000 km below cloud tops:
20,000K, 100 million bars, mix of hydrocarbons and rock.
6. Compare the core of Jupiter to Earth. Jupiter’s core is made of rock, metals and hydrogen compounds. Earth has a solid
core with a liquid outer core. Liquid rock.
7. How are the interiors of Uranus and Neptune different from Jupiter’s and Saturn’s? They have water, methane and
ammonia and J&S do not.
8. Jupiter’s atmosphere is made up almost entirely of what two elements? Hydrogen and Helium.
What are the dark and light stripes which are called belts and zones on Jupiter? Different altitudes of clouds, red is low and white
high. Is the Coriolis Effect
9. important on Jupiter? yes
10. What is the great red spot on Jupiter? A storm
11. What powers the atmospheres of the Jovians? The coriolis effect I think, not for sure though.
12. Describe the internal heat of each Jovian. What is the source of this heat in each case? Jupiter, twice the heat it absorbs,
because its still cooling. Saturn, twice the heat it absorbs, because of helium rain. Uranus has no internal heat.
Neptune, twice the heat it absorbs, perhaps because it is still contracting.
13. Why are Neptune and Uranus bluish in color? Because they have so much methane gas and it absorbs red light and
reflects blue light.
14. Compare Jupiter’s magnetic field to that of the other planets. It is extremely massive.
15. What is the seat of the magnetic fields of each of the Jovians? I don’t know what this is asking.
16. What is unusual about the fields of Neptune and Uranus? That they are so far off from where their axis is.
17. Know the interesting properties and geology of the Jovian Moons as well as their atmosphere (when applicable) to the
level of detail discussed in class! These are extremely interesting objects and there will be a number of questions about
them!
18. Know the ring systems of the Jovians, their discoveries, and theories as to how they form and how long they may last to
the level of detail that we discussed in class!