Lecture 7 - The Terrestrial and Jovian Planets

Question 1

what are the 3 layers of Earth?

Answer 1

1. Core
2. Mantle
3. Crust

Question 2

what is the density of the core?
what is it made of? what is happening to these elements?
outer core vs. inner core

Answer 2

core has highest density

made of nickel and iron –> heavy metals slowly burning away via nuclear fission

outer core is molten, inner core is solid bc of high pressure even tho higher temp

Question 3

what is the density of the mantle?

what is it made of? how do we know this?

Answer 3

moderate density

made of silicon + oxygen, we know about this because of earthquakes propagating soundwaves thru it

Question 4

what is the density of the crust?

what is it made of?

where is it thick? where is it thin?

Answer 4

lowest density

made of granite, basalt

thick where land is, thin where water is

Question 5

describe what happens during differentiation

what does this indicate about Earth’s temp?

Answer 5

gravity pulls high-density material to center and low-density material rises to surface –> allows material to be separated by density

planet must have been hot enough for interior rock and lithium to melt

Question 6

is the lithosphere related to lithium?

Answer 6

no

Question 7

what is the lithosphere? what happens when it is thick/thin?

Answer 7

outer layer of cool, rigid rock that “floats” on warmer, softer rock beneath

thin = brittle, cracks easily
thick = stronger, prevents passage of molten rock so there are less volcanic eruptions and mountain formations

Question 8

which planet is taken up the most by its metal core?

Answer 8

mercury

Question 9

what do geological processes on planets lead to? what is this driven by

Answer 9

1. volcanic eruptions
2. earthquakes
3. erosion

driven by interiors heating up and cooling off from sun’s nuclear fusion

Question 10

what is fueled by heat of nuclear fusion from the sun? what are 2 exceptions?

Answer 10

EVERYTHING is fueled by heat of nuclear fusion from sun

1. except heat pumps using fluid to heat from core of earth
2. except tidal power using energy of tides extracted from orbits to generate power with turbines

Question 11

what are the 3 sources of energy for heating planets?

Answer 11

1. accretion
2. differentiation
3. radioactive decay

Question 12

how is energy produced via accretion?

Answer 12

gravitational PE converted to KE converted to thermal energy when planets were young

Question 13

how is energy produced from differentiation?

Answer 13

light materials rise, dense materials fall and convert gravitational PE to thermal energy when planets were young

Question 14

how is energy produced from radioactive decay?

Answer 14

mass-energy contained in nuclei converted to thermal energy (from sun)

Question 15

why are planets slowly cooling?

Answer 15

due to fewer collisions

Question 16

what are the 3 sources for planets cooling?

Answer 16

1. convection
2. conduction
3. radiation

Question 17

what is convection?

Answer 17

transports heat as hot material rises and cool material falls

Question 18

what is conduction?

Answer 18

transfers heat from hot to cool material

Question 19

what is radiation?

Answer 19

sends energy to space

Question 20

what is geological activity controlled by?

Answer 20

planetary size controls geological activity

Question 21

what happens to smaller planets? what has happened to mercury and the moon?

Answer 21

cool off faster and harden earlier bc easier to get heat out

mercury and the moon now geologically dead

Question 22

what happens to craters if a planet has no crust?

Answer 22

if a planet has no crust, there would be no craters

Question 23

are magnetic fields constant?

Answer 23

no, they change very quickly

Question 24

what cause magnetic fields in a planet(2)?

Answer 24

1. motions of charged particles
2. molten core

Question 25

are the magnetic poles on Earth a monopole? what happens to magnetic North each year?

Answer 25

North and South magnetic poles are always connected --> NEVER a monopole magnetic north changes every year

Question 26

what are the 3 requirements for magnetic fields on a planet?

Answer 26

1. molten, electrically conducting interior (moving charged particles) 2. convection 3. moderately rapid rotation

Question 27

which of convection, conduction, or radiation is responsible for how energy is transported from sun to Earth?

Answer 27

RADIATION

Question 28

What does Einstein's theory of relativity prove?

Answer 28

can never prove anything --> has been disproven

Question 29

when does Einstein's theory apply? when is it a poor description of events?

Answer 29

applies only when things are really heavy (planets, black hole) poor description when gravity and quantum mechanics are involved bc Einstein doesn't account for uncertainty

Question 30

what are 2 situations where Einstein's theory doesn't make sense?

Answer 30

1. doesn't make sense with Big Bang 2. doesn't make sense with Black Hole --> Einstein says infinite density

Question 31

what are 4 processes that shape surfaces?

Answer 31

1. impact cratering 2. volcanism 3. tectonics 4. erosion

Question 32

how does impact cratering shape surfaces? when did most of this occur?

Answer 32

planet impacted by asteroids or comets that releases enough energy to vapourize solid rock and debris flying onto planet or into space most craters occurred soon after the solar system was formed

Question 33

are there more large or small craters? what does this indicate?

Answer 33

more small craters --> indicates more small planetesimals formed during the birth of the solar system

Question 34

why do we not see the meteorite? where do we find fragments?

Answer 34

cannot see the meteorite bc the heat produced caused it to vapourize bit often find fragments within or near the crater

Question 35

is there a lot of energy in the collision of a crater?

Answer 35

YES

Question 36

What is volcanism? what does it require?

Answer 36

eruption of molten rock (magma) thru lithosphere onto surface --> then molten rock becomes lava at surface requires internal heat

Question 37

what does the thickest type of lava make?

Answer 37

steep-sloped volcanoes --> stratovolcanoes

Question 38

what type of volcano does slightly runny lava make?

Answer 38

shallow-sloped volcanoes --> shield volcanoes

Question 39

what does runny lava make?

Answer 39

flat volcanic plains like on the moon

Question 40

is the moon geologically dead or alive?

Answer 40

dead

Question 41

what are tectonics? what causes it and what is required for this process?

Answer 41

disruption of a planet's surface by internal stresses caused by convection of the mantle that produces stresses in the crust --> Tectonic Forces requires internal heat

Question 42

what creates mountain ranges?

Answer 42

compression of crust from tectonics

Question 43

what creates valleys?

Answer 43

forms where crust is pulled apart

Question 44

how do Earth's continents slide around?

Answer 44

slide around on separate plates of crust

Question 45

describe plate tectonics on earth

Answer 45

plates are produced from ongoing stress of mantle convection that fractures the lithosphere into >dozen pieces plates move over, under, and around each other

Question 46

what do measurements of plate motions tell us?

Answer 46

tells us past and future layout of continents and geological features

Question 47

describe structures on mercury that are due to tectonics and how does this affect mercury's size?

Answer 47

mercury has long cliffs which indicate it shrank early in its history

Question 48

what causes erosion?

Answer 48

wind, water, ice --> break down or transport rock

Question 49

when did most cratering occur?

Answer 49

in the first billion years

Question 50

what does it mean if a planet has many craters? what does this indicate about the age of the surface

Answer 50

its surface has not changed much in the past 3 billion years more craters = older surface

Question 51

describe cratering on the moon what happened to the younger regions? why do we know that the surface has remained unchanged for billions of years?

Answer 51

some areas more heavily cratered than others younger regions were flooded by lava after most cratering but we see many craters so the surface has remained virtually unchanged for billions of years

Question 52

does earth have a lot or few craters? what does this indicate about its age?

Answer 52

earth has very few craters so it is younger

Question 53

describe Lunar Maria vs Lunar Highlands in terms of craters and age when did heavy bombardment likely end? why?

Answer 53

Lunar Maria - smooth + dark, less craters - 3-3.9 billion years old Lunar Highlands - craters on top of craters - 4.4 billion years old therefore, the lava flow that made the volcanic plains had occurred by that time and heavy bombardment must have ended by 4 billion years ago

Question 54

why do we not see significant crater features on Earth like Mercury and the Moon?

Answer 54

erosion and volcanic activity on Earth has resurfaced the earth since it was heavily bombarded

Question 55

what happens to geology on smaller planets? larger planets?

Answer 55

SMALLER: cool off faster and harden earlier so geology ends soon bc the surface stops changing sooner --> therefore more craters, no atmosphere so no erosion LARGER: remain warm to cause convection in mantle, promote volcanism, tectonics, and erosion due to gravity retaining an atmosphere, and molten core may produce magnetic field if rotation is fast enough

Question 56

describe the atmosphere of larger planets

Answer 56

larger atmosphere bc their

Question 57

describe the relationship between distance from sun and erosion

Answer 57

close to sun: - too hot for rain, snow, ice - difficulty in retaining an atmosphere - less erosion far from sun: - too cold for rain - less erosion medium distance: - liquid water

Question 58

how does the speed of rotation affect: 1. weather 2. erosion 3. magnetic field

Answer 58

SLOW ROTATION: 1. less weather 2. less erosion 3. weak magnetic field FAST ROTATION: 1. more weather 2. more erosion 3. stronger magnetic field

Question 59

what were the canals on mars initially thought to be?

Answer 59

initially thought to be machine-built by martians

Question 60

describe cratering on mars

Answer 60

amount of cratering varies across Mars' surface many early craters have been erased

Question 61

describe volcanism on mars. what is its most significant volcano?

Answer 61

mars has many large shield volcanoes Olympus Mons is the largest volcano in solar system

Question 62

what is a feature of Mars that is thought to have originated from tectonics?

Answer 62

system of valleys called Valles Marineris

Question 63

why do we believe water likely flowed on mars at one point?

Answer 63

we can see dried up riverbeds in close-up photos