Terrestial Planets Flashcards
Name the terrestrial planets
Mercury, Venus, Earth, Mars
Where are terrestrial planets located?
0.4-1.52AU
What are typical density of terrestrial planet?
~5000kg/m^3
How did the moon form?
Thought to be result of massive collision as the planets were forming
How do we know how moon formed?
•too big for earth to capture
•tidally locked
•composed of material similar to earths mantle and lithosphere
•small core
•age of surface rocks similar to age of solar system
Impact Cratering
Form when an asteroid or comet hits the surface of a planet
•crater generally 10 times as wide as the object and has depth similar to object size
Which terrestrial planet has been subject to most crater bombardment?
All the same
Why was crater bombardement heavier in early solar system?
Still a lot of debris left over from the Proto-planetary disk
What is the core?
Densest material-metals such as nickel and iron
What is the mantle?
Rocky material of modest density-minerals containing for example silicon and oxygen
What is the crust?
Lowest density rocks-e.g., granite, basalt
What is the lithosphere?
Outer shell of most solid rock
What are the two types of earthquakes?
•P waves-longitudinal
•S waves-transverse
What waves are stopped by molten outer core?
P Waves (S waves can only travel in solids)
What allows us to develop a model of earths interior?
Analysis of seismic waves
How do we know interior structure of other planets?
Detailed mass and shape measurements
What are the 3 internal heat sources?
Heat of accretion, heat from differentiation, heat from radioactivity
What is heat of accretion?
Accreting planetesimals release gravitational potential energy
What is heat from differentiation?
As dense material sinks it also releases gravitational potential energy
What is heat from radioactivity?
Rocks and metals contain radioactive isotopes that release energy when they decay
How do planets cool?
Planets lose internal heat by transporting the energy to the surface and radiating it away: convection, conduction, radiation
When does volcanism occur?
When underground molten rock finds its way through the lithosphere to the surface
What are the different volcanoes?
•Plains like in moon formed by runniest lava flattening out
•shield volcanoes formed by thicker lava (Hawaii/mars)
•strato-volcanoes formed by thickest lava(earth)
What is tectonics?
Any surface reshaping process
•stretching or compression of the lithosphere
What is erosion?
•breakdown of rock through action of ice,liquid, or gas
How are craters erased?
•formed by bombardement but can be erased by activities such as volcanism, tectonics, and erosion( driven by internal heat)
Describe the lunar Maria?
•smooth
•formed by a flood of lava
•Maria lava heated by radioactive decay in first few hundred mill years after formation
What does lack of craters in Maria imply?
Early heavy bombardment and very few impacts afterwards
Describe Mercurys surface
•heavily cratered, some lava plains
•Some very high cliffs( contraction of core and mantle,deforming crust)
•Caloris Basin (crater half of radius)
Describe Venus’s surface
•many lava plains and volcanoes, contorted crust
•no erosion evident as no wind
•crater count suggests surface age of 750 million yrs
Why is earths lithosphere broken into different plates?
Forces of underlying mantle convection
Why does Venus have no plates?
•thicker and stronger lithosphere
•could be because water evaporated faster on Venus than on earth
Describe Mars’s surface
•southern hemisphere more heavily cratered than the north( southern surface older)
•geological activity has erased craters in north
•north lower elevation
•large impact basin in south
How high is Olympus mons?
26km
Why is Olympus mons volcano bigger than earths?
Moving tectonics on earth cause volcano hotspots to move
Describe water on Mars
•mainly in the form of polar ice, up to a metre thick
•ancient water flow:sedimentation
•recent water flows:•gullies and craters and liquid water unstable
•radar reveals liquid water lakes under ice caps
