Inner Solar System Flashcards
How does Venus appear in evening or morning sky? why?
A bright object, it was high albedo
What is Venus covered in?
Thick layer of white clouds
Venus Has phases, what range in appearance do we see?
Narrow crescent to an almost disk.
Venus can be seen at any point in the day. T/F?
False, only evening or morning
Does venus have moons?
No
Venus is similar, in size, to earth. T/F?
True
What do radar measurements tell us about venus?
Very slow rotation period, 243.01 days, and is retrograde
Why does Venus display retrograde motion?
Large impact with planetismal
Effect of thick atmosphere perturbing Venus’ rotation
Does venus have a magnetic field?
No
What are venus clouds formed from?
Sulphuric acid
Atmosphere composition of Venus
96% CO2, 3.5% N2, 0.5% H20 h2SO4 HCl and HF
What component of Venus’ atmosphere could indicate life?
Phosphine gas (PH3)
Why does CO2, a greenhouse gas, dominate Venus’ atmosphere?
Venus didnt have enough water to cause weathering of rocks, which wouldve removed CO2 from atmosphere.
Describe Venus’ protective magnetic field
Very low
What happened to Venus’ water?
UV radiation broke up water molecules in upper atmosphere and hydrogen was lost to space.
How did this lack of water in venus result in a runaway greenhouse effect?
Limited water gave no possibility to store Co2 in rocks, planet became very hot. ST = 472 degrees Celsius
What does Venus’ surface appear to be?
Basalt
Why were soviet spacecrafts (Venera) destroyed when they landed on the surface of Venus?
High temp, pressure and acidic atmosphere.
How do we obtain images of large areas of Venus’ surface?
Radar mapping
What can Venus’ clouds be penetrated by?
Radio waves
What did the Magellan space probe of venus show?
Lava flows
Classic features of an impact crater?
Smooth floor, central peaks, rough surface of ejecta
Dark halo around some Venus Impact Craters. Why?
Smooth area of pulverised rock produced by shock wave from meteorite
Has Venus ever had volcanic activity?
Yes, many volcanoes and structures associated with a period of intense volcanic activity about 500 million years ago.
What are coronae
Circular bulges caused by magma rising from below the surface
What are pancake domes?
Circular structures formed by lava
Tectonic activity on Venus
Ranges of wrinkled mountains
When is Mercury seen? Why?
Only in twilight, due to close proximity to Sun.
Does mercury have moons?
No
Ha an atmosphere been detected from Mercury?
No, stars blocked out abruptly
What telescope measured Mercurys surface temp?
Arecibo radio telescope
Mercurys rotation and orbital period
Rotation = 59 days
Orbital = 88 days
Mercury Solar day length/
2 Years
How many times does mercury rotate in 2 years?
3
What cellestial object is Mercury a similar size to?
The Moon
Describe the presence of craters on Mercury
Heavily cratered, many sizes and different ages.
Are basins present on Mercury/
Yes, some large basins
Caloris Basin
Huge impact basin on Venus’ surface, partially filled by lavo flows and surrounded by concentric rings of hills
Why is Venus’ terrain described as weird?
terrain on opposite side of Caloris impact is weird, jumbled and chaotic.
How did this weird terrain come about
Shock waves traversed Mercury from the Caloris Basin impact to the opposite side of the planet
What are Venus’ lobate scarps?
Curved Cliffs, newever than many craters and cut across them.
Where did Venus’ scarps come from?
As mercury cooled it shrank, causing surface wrinkles. Lobate scarps are wrinkles.
First Messenger results of Mercury
Wtaer-ice present in craters
Possibly relatively younf
Prokofiev crater reveals features of frozen deposits
Does Mercury have a magnetic field?
Yes, a weak magnetic field.
Describe Mercurys interior?
More dense than moon
Normal, rocky surface
Large metallic core (mainly iron)
Is mercurys core fully solid?
No - partially molten
What caused flooding of mercurys cratered surface?
Period of lava flow, perhaps triggered by Caloris impact
Is Mercury still volcanically active?
No
Final stage of Venus’ planet evolution
Slow Erosion by micro-meteorites.
Describe the rotation of the moon
Locked to orbit due to gravitational tidal resonance (Same side always faces Earth)
How many rotations does the moon undergo about its axis per orbit around earth?
1
How does tidal resonance in the moon come about?
Differences in gravitational attraction between Earth and Moon
Why can we see slightly more than half of the moons surface?
Elliptical orbit
Describe the Moons appearance
Heavily cratered, with large impact craters, basins and dark plains called Maria.
Describe Maria on the moon
Not completely smooth (contain ridges, geological faults and small craters)
Features of Impact Bains
Circular with raised rim
Central peak where rock rebounded
What is the material thrown out of an impact crater called?
Ejecta
Steps of typical impact crater formation
- A body strikes the surface of the Moon
- It buries itself below the surface
- An explosion and a crater is formed
- The rocks in the center rebound
How was the Maria created?
Large impacts cause fissures in crust, allow lava to flow toward surface
Compare far side of the moon to near side
More cratered, no maria, more mountains
Why is the far side of the moon different to the near side?
More exposure to comets, thicker crust.
Describe the Interior of the Moon
Crust, which is thinner on side facing earth
Deep mantle of brittle rock
Low density, rules out an iron core more than a few hundred km in diameter.
Does moon have a liquid metallic core? why?
No - cooled rapidly because so small
Moons Magnetic field
No large-scale magnetic field, No dynamo mechanism
Does the Moon have an atmosphere? How do we know this?
No, completely dark shadows, stars obscured by moons disk, gravitational field too weak
What is the Large Impact Theory for the formation of the moon?
- Earth was struck by a smaller body, perhaps the size of mars, called Theia
- Impact was a bit off-centre
- Impact stripped much of the mantle of the body from its core and removed much of earths mantle
- Most of the core of the second body and some of the material from both mantles fell back to earth
- remainder material coalesced and formed the moon.
What does the Large Impact Theory explain?
Moons low density, Similar chemical compositionof crust to Earths, Moon being dry, near and far sides having different thicknesses
What two types of seismic waves (sound waves) do Earthquakes produce?
S (shear) and P (pressure)
Do S or P waves travel faster?
P waves
Differences between S and P waves?
S - produce displacement perpendicular to direction of travel
- cant travel in liquid
P - can travel through biology
Commonality of S and P waves
Reflect partially at a boundary
What has the study of Seismic waves told us about earths interior?
Crust of solid low density rocks at the surface
Dense rocky mantle below the crust
Outer part of earths core is liquid and inner is solid
What is Earths core made of?
Iron, nickel and a small fraction of other elements
Requirements for a magnetic field
- Electrically conducting liquid core
- Convection currents in the core
- Fast rate of rotation
What is the magnetosphere
Region of space where motion of charged particles is controlled by planets magnetic field, not solar wind
What does magnetosphere do to solar wind
Keeps solar wind away from the surface of the planet
What is Bow shock
Interference with solar wind
What are Auroras
Light displays at earths magnetic poles
How do auroras come about?
Electrons are accelerated by voltage in magnetosphere, and strike upper atmosphere causing emission of light.
When are auroras the most vivid and active?
During geomagnetic storms, caused by ejections from Sun striking earth.
During geomagnetic storms, auroras can be seen _____ than normal
Closer to equator
What is the lithosphere?
Region of right, low density rock in the crust and top of the mantle
What is the asthenosphere?
Lies below the lithosphere in the mantle. Rock is close to melting point and very plastic.
What are tectonic plates
Large, rigid sections of the lithosphere.
What does plasticity allow the tectonic plates to do?
Move slowly but steadily over Earths surface
What are the two types of tectonic plates?
Oceanic, Continental
What are the two typed of tectonic plates made for?
Oceanic - basalt
Continental - Rock from volcanoes
How are oceanic plates created?
Convection currents in mantle
Where do continental plates reside?
Float on the mantle, forming continents and associated continental shelves under shallow seas.
Continental plates are less ____ than oceanic plates
dense
What is continental drift?
Tectonic plates move over earths surface, typically a few cm per year
How many years have we had continental drift?
200 million years
What happens at mid ocean ridges/rifts?
Material rises to ocean floor and spreads outward
How is the rising material formed
Molten rock is magnetised by earths magnetic field as it solidified.
What forms subduction zones?
Caused by two plates colliding, one pushed under the other
What does subduction of oceanic plate under another give?
Volcanic Island Arcs
What does subduction of oceanic plate under a continental plate give?
Ocean Trenches
Where does Mountain Building occur?
Collision of continental plates
What does Mountain Building give?
Ranges of mountains with folded rocks
What zones are volcanoes associated with?
Subduction zones
When building a continent, what is the key aspect of the lava being expelled?
Less dense than material of upper mantle
Rocks float on the _____ and form the continents.
Mantle
What are continents shaped by?
Volcanic activity, plate tectonics and erosion
Why are shield volcanoes called that?
Lava flows easily and their shape is like that of an inverted shield
What do Island Chains prove?
That tectonic plates are moving.
What causes a chain of volcanic islands?
Drift of lithosphere over asthenosphere causes surface to move over hot spot.
Structure of Stratiform Volcanoes
Smaller and more pointed than shield volcanos
What are stratiform volcanoes associated with?
Volcanoes at subduction zones
Original source of atmosphere
Release of gases from hot interior and by volcanic activity.
What was different about the composition of the atmosphere orignally?
Orginal atmosphere was much thicker, and mainly CO2, water vapour and N2
How was most of carbon dioxide removed from earths atmosphere?
Liquid water resulted in weathering of rock
What does photosynthesis produce and remove?
Produces oxygen, removes CO2
Effects of photosynthesis
Organisms that use oxygen
Ozone layer
What does the ozone layer block?
UV radiation
4 Components of the Atmosphere
Thermosphere, Mesosphere, Stratosphere, Troposphere
1st stage of Earth Evolution
Accretion and Differentiation
2nd stage of earth evolution
Period of intense bombardment
3rd stage of earth evolution
Flooding by lava and/or water
4th stage of earth evolution
Period of slow evolution
What gives the earth thick layers of sediment
Weathering of mountains
How have craters from comets been hidden?
Effects of tectonic plate activity.
What must a theory for the formation of the Solar System explain?
- The patterns of the motions of the planets
- 2 planet categories : Terrestrial and Jovian
- Existence pf huge numbers of asteroids and comets, and why they reside where they do
- Make allowances for exceptions
What is De Buffon’s Passing Star Model?
Planets formed from material pulled from the Sun by another star passing close by.
De Buffons Passing star Model is an example of a catastrophic model.
What does this mean?
The result of a singular, peculiar event.
What does De Buffons Passing Star Model suggest about stars?
That very few stars have planets.
Problems with De Buffons Passing Star Model
- We have way too many planets
- Material from sun would be too hot to form planets
- Stable, almost circular orbits are unlikely
- Doesn’t explain varying properties of planets
What is the Solar Nebula Hypothesis
Sun and planets formed from a nebula of gas and dust.
What is an evolutionary model e.g - Solar Nebula Hypothesis
Process occurred slowly without requiring an unusual event
Stage 1 of the Solar Nebula Hypothesis
Sun and planets formed at the same time from a contracting rotating cloud of gas.
Formation of planets is common
Stage 2 of Solar Nebula Hypothesis
Cloud rotates, becomes smaller and the disc speeds up and flattens
How is the sun formed in stage 2 of the solar nebula hypothesis
Gravity caused a concentration at the centre of the disc
How are accreting bodies formed in the Solar Nebula Hypothesis
Further from the centre, grains of dust and molecules of gas start to form other bodies by a process called accretion
