Lecture 7 - The Terrestrial and Jovian Planets Flashcards
what are the 3 layers of Earth?
- Core
- Mantle
- Crust
what is the density of the core?
what is it made of? what is happening to these elements?
outer core vs. inner core
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
what is the density of the mantle?
what is it made of? how do we know this?
moderate density
made of silicon + oxygen, we know about this because of earthquakes propagating soundwaves thru it
what is the density of the crust?
what is it made of?
where is it thick? where is it thin?
lowest density
made of granite, basalt
thick where land is, thin where water is
describe what happens during differentiation
what does this indicate about Earth’s temp?
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
is the lithosphere related to lithium?
no
what is the lithosphere? what happens when it is thick/thin?
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
which planet is taken up the most by its metal core?
mercury
what do geological processes on planets lead to? what is this driven by
- volcanic eruptions
- earthquakes
- erosion
driven by interiors heating up and cooling off from sun’s nuclear fusion
what is fueled by heat of nuclear fusion from the sun? what are 2 exceptions?
EVERYTHING is fueled by heat of nuclear fusion from sun
- except heat pumps using fluid to heat from core of earth
- except tidal power using energy of tides extracted from orbits to generate power with turbines
what are the 3 sources of energy for heating planets?
- accretion
- differentiation
- radioactive decay
how is energy produced via accretion?
gravitational PE converted to KE converted to thermal energy when planets were young
how is energy produced from differentiation?
light materials rise, dense materials fall and convert gravitational PE to thermal energy when planets were young
how is energy produced from radioactive decay?
mass-energy contained in nuclei converted to thermal energy (from sun)
why are planets slowly cooling?
due to fewer collisions
what are the 3 sources for planets cooling?
- convection
- conduction
- radiation
what is convection?
transports heat as hot material rises and cool material falls
what is conduction?
transfers heat from hot to cool material
what is radiation?
sends energy to space
what is geological activity controlled by?
planetary size controls geological activity
what happens to smaller planets? what has happened to mercury and the moon?
cool off faster and harden earlier bc easier to get heat out
mercury and the moon now geologically dead
what happens to craters if a planet has no crust?
if a planet has no crust, there would be no craters
are magnetic fields constant?
no, they change very quickly
what cause magnetic fields in a planet(2)?
- motions of charged particles
- molten core
are the magnetic poles on Earth a monopole? what happens to magnetic North each year?
North and South magnetic poles are always connected –> NEVER a monopole
magnetic north changes every year
what are the 3 requirements for magnetic fields on a planet?
- molten, electrically conducting interior (moving charged particles)
- convection
- moderately rapid rotation
which of convection, conduction, or radiation is responsible for how energy is transported from sun to Earth?
RADIATION
What does Einstein’s theory of relativity prove?
can never prove anything –> has been disproven
when does Einstein’s theory apply? when is it a poor description of events?
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
what are 2 situations where Einstein’s theory doesn’t make sense?
- doesn’t make sense with Big Bang
- doesn’t make sense with Black Hole –> Einstein says infinite density
what are 4 processes that shape surfaces?
- impact cratering
- volcanism
- tectonics
- erosion
how does impact cratering shape surfaces?
when did most of this occur?
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
are there more large or small craters? what does this indicate?
more small craters –> indicates more small planetesimals formed during the birth of the solar system
why do we not see the meteorite? where do we find fragments?
cannot see the meteorite bc the heat produced caused it to vapourize
bit often find fragments within or near the crater
is there a lot of energy in the collision of a crater?
YES
What is volcanism? what does it require?
eruption of molten rock (magma) thru lithosphere onto surface –> then molten rock becomes lava at surface
requires internal heat
what does the thickest type of lava make?
steep-sloped volcanoes –> stratovolcanoes
what type of volcano does slightly runny lava make?
shallow-sloped volcanoes –> shield volcanoes
what does runny lava make?
flat volcanic plains like on the moon
is the moon geologically dead or alive?
dead
what are tectonics? what causes it and what is required for this process?
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
what creates mountain ranges?
compression of crust from tectonics
what creates valleys?
forms where crust is pulled apart
how do Earth’s continents slide around?
slide around on separate plates of crust
describe plate tectonics on earth
plates are produced from ongoing stress of mantle convection that fractures the lithosphere into >dozen pieces
plates move over, under, and around each other
what do measurements of plate motions tell us?
tells us past and future layout of continents and geological features
describe structures on mercury that are due to tectonics and how does this affect mercury’s size?
mercury has long cliffs which indicate it shrank early in its history
what causes erosion?
wind, water, ice –> break down or transport rock
when did most cratering occur?
in the first billion years
what does it mean if a planet has many craters? what does this indicate about the age of the surface
its surface has not changed much in the past 3 billion years
more craters = older surface
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?
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
does earth have a lot or few craters? what does this indicate about its age?
earth has very few craters so it is younger
describe Lunar Maria vs Lunar Highlands in terms of craters and age
when did heavy bombardment likely end? why?
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
why do we not see significant crater features on Earth like Mercury and the Moon?
erosion and volcanic activity on Earth has resurfaced the earth since it was heavily bombarded
what happens to geology on smaller planets? larger planets?
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
describe the atmosphere of larger planets
larger atmosphere bc their
describe the relationship between distance from sun and erosion
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
how does the speed of rotation affect:
1. weather
2. erosion
3. magnetic field
SLOW ROTATION:
1. less weather
2. less erosion
3. weak magnetic field
FAST ROTATION:
1. more weather
2. more erosion
3. stronger magnetic field
what were the canals on mars initially thought to be?
initially thought to be machine-built by martians
describe cratering on mars
amount of cratering varies across Mars’ surface
many early craters have been erased
describe volcanism on mars. what is its most significant volcano?
mars has many large shield volcanoes
Olympus Mons is the largest volcano in solar system
what is a feature of Mars that is thought to have originated from tectonics?
system of valleys called Valles Marineris
why do we believe water likely flowed on mars at one point?
we can see dried up riverbeds in close-up photos
