Astronomy Exam 3: Craters and Planetary Terrain

Heat Sources of Jupiter/Saturn

1. Gravitational Tidal Heating from friction 2. Collisions liquefy planetary surfaces 3. Decay of Radioactive Elements 4. Differentiation that causes friction 5. Primordial Heat (from formation of planet)

Tharsis Montes

Arsia Mons; Pavonis Mons; Ascraeus Mons

plate tectonics

Earth's lithosphere is broken into plates that move

Evolution of Terrestrial Planets' Interiors

FIRST 600 MILLION YEARS, the impact rate was so high that the outer layers were melted (even if the inside was cool); caused an ocean of magma on the surface of planets; final bombardment was at 4 BILLION YEARS

Mercury Lobate Scarpes

Mercury was born with a huge Iron core, when it cooled, parts of the crust collapsed

Beta Regio

a volcanic rise of Venus; formed from volcanic pressure pushing the surface up; contains largest volcano of Venus; (exactly like the Tharsis bulge)

Equation of State

any equation involving pressure(P), density(p), and temperature(T); relates pressure to density and temperature

Regular Moons

anything like Io, Ganymede, Titan, Triton, Callisto, Europa

Titan (Saturn)

atmosphere of primarily Nitrogen; methane condenses on surface as liquid (triple point is on Titan)

Lowest Velocity (crater type)

bowl shape

Relative Ages of Planets

can be found by crater densities; planets with no atmosphere can be aged by looking at craters (formation probably occurred in the first 600 Million years of the solar system); Planets are around 5 BILLION YEARS OLD

Intermediate Velocity (crater type)

central peak

gabbro

coarse-grained igneous rock formed when magma cools slowly in the crust

Thrust faults

compression under the surface pushes the crust up and over the side of another crust

Evolution of Venus/Earth Interior

cool/undifferentiated planet with magma ocean from bombardment; heat caused Iron to sink to the core and solidify; asthenosphere and lithosphere formed and still active; (VENUS has a little magnetic field due to its slow rotation)

siderophiles

elements that bond to higher-density iron minerals that concentrate near the lower-mantle/core of planets

lithophiles

elements that bond to low-density silicate that concentrates on the surface of planets

Hydrostatic Equilibrium

fluid is at rest; OR the flow velocity at each point is constant; balance between pressure and gravity (pressure of layer must equal gravity of that layer)

Lunar Seas

formed in the first 600 million years of solar system; impact basins were filled with lava/magma and cooled to make them flatter

Galilean Satellites

four largest moons of Jupiter; Io, Europa, Ganymede, Callisto; mimic the way the solar system planets are different (inner have more stone/heat and outer have more ice)

Ithica Chasma

giant canyon/crack on the moon that goes around the whole moon; located on Tethes

Tethes (Saturn)

has Ithica Chasma

Mimas (Saturn)

has a crater called Hershel that is the largest crater on a planet compared to its size

Landscape of Venus

has coronae that look like flattened pancakes from volcanic activity (ONLY PLACE TO HAVE CORONAE); shallow/level relief; few volcanoes; few craters due to lava flow; strong erosion from thick atmosphere

impact bombardment

has to be a stage in birth of all planets; Mercury was proof

Caloris Basin

huge impact basin on Mercury; formed from an enormous impact during the FIRST BILLION YEARS of the solar system (1 BY)

Tharsis Bulge

huge volcanic plateau on Mars; home to the largest volcanoes in the solar system; volcanic activity raised the land

Europa

ice planetessimal; believed to have a huge ocean covered by a layer of ice; tidal heating/heat from core keeps the ocean warm enough (possible for life)

Io

innermost Galilean Satellit; 4th largest; highest density; least amount of water; tons of volcanic activity; dense refractory materials

Evolution of Moon Interior

intense cratering resulted in a magma ocean and solid core; craters were flooded by magma; since the moon is small it cooled quickly resulting in a large lithosphere and a smaller asthenosphere

Evolution of Mercury Interior

lack of atmosphere resulted in intense cratering like the moon; these craters were not covered like the moon's; magma ocean resulted in a thin lithosphere and thick asthenosphere; like the moon, Mercury cooled rapidly which eliminated the asthenosohere and resulted in a lithosphere that takes up the entire mantle; today it is just crust, lithosphere, iron core

Landscape of Mars

large mountains from volcanic activity underneath the surface; huge volcanoes and canyons from a decrease in volcanic activity; some erosion due to the atmosphere and storms

Megaregolith

larger layer of pulverized material; probably from intense cratering in early moon life; thicker with bigger chunks of material

Ganymede

largest Jupiter satellite; highly differentiated; magnetic field with active interior (metallic core); ice mantle with fractures (ice-plates may act like tectonic plates); watery mantle with mud/rock core

Olympus Mons

largest volcano in solar system (located on Mars); located on the outer edge of the Tharsis bulge

mare flooding (moon)

lava flooding craters on the moon that flattened the plane of the craters (seeped from fracture channels)

Regolith

layer of unconsolidated rock material on the Moon; dust, soil, broken rock; caused by constant bombarding of meteorites on the moon

Lobate Scarpes

long/curved structures that look like valleys; formed from compression/thrust faults;

Moon Compositions

made of ice, rock, or both; formed by accretion differentiation; irregular moons are other moons that are probably captured asteroids

Evolution of Martian Interior

magma ocean from bombardment; iron sunk to the core; asthenosphere caused a lot of volcanic activity to erupt over the planet; lithosphere began to grow as the planet cooled; today is large lithosphere, smaller asthenosphere, and solid iron core

Enceladus

moon on Saturn that ejects water into orbit around Saturn; water volcanoes

outer core

mostly liquid

S-Waves

motion of particles like the ocean (doesn't propagate in liquid); only in the outer core

Landscape of Mercury

no atmosphere/erosion; lots of craters; last impact bombardment was 4 BILLION YEARS AGO

Callisto

outermost Galilean satellite; second biggest; lowest density; no significant tidal heating; tons of craters; highest ice; least active interior; undifferentiated rocky core

Coronae

oval/crown-like feature of volcanic activity; occurs when volcanic activity lifts the surface, then the surface collapses when volcanic activity decreases

P-Waves

pressure waves that propagate like sound (propagates in liquid); out of the core and into the mantle

inner core

probably solid metal due to the high amount of pressure

shock metamorphic rocks

rocks melded together from insane impact heat and pressure (shock quartz)

Bulk Compositions of Jupiter/Saturn

same composition of the Sun (80% Hydrogen); gas=>liquid H2=>liquid/metal H2=>ice H2O/CH4/NH3=>rock/metal core

Highest Velocity (crater type)

several miles in size; looks like a bullseye (concentric rings); huge one on Callisto called Valhalla; always MADE IN FIRST 600 MILLION YEARS (last time for huge impacts)

Evolution of Gas Giants

similar to the Sun; not enough mass and energy to become a star; developed moons that resemble the planets in the solar system; interiors contain mostly Hydrogen with some heavier elements consolidated at the core

asthenosphere

slushy mixture of water/ice/soil; where high-temp. minerals are solid and suspended in low-temp. minerals that are liquid; in the upper mantle

palimpsests

smooth circular patches that are icy scars (basically filled in craters where the ridges have been erased); found on ice moons (Callisto/Ganymede); forms in ice

Crater Types and Kinetic Energies

the amount of kinetic energy instantly turns into the heat at impact

accretion differentiation

the differentiation that occurs when planets/planetessimals gain substances from impacts; differentiation from layers caused by impacts (impacts of different material)

Valles Marineris

vast canyon on the Martian equator (east of tharsis); largest canyon in the solar system; formed from a tectonic crack when the crust thickened and the Tharsis region grew

Calderas

volcanic crater caused by collapse; extinct volcanoes; formed when a volcanic mountain collapses; summit of Olympus Mons is the biggest

anorthosites

volcanic origin

Lunar Rocks

volcanic rocks, shock metamorphic rocks, anothositic rocks, gabbro, olivine, iron; similar to Earth, but it cooled rapidly

Seismic Waves

waves from movement in Earth's crust that moves the crust; tells us that there is liquid in Earth's layers/core

Crater Saturation Equilibrium

when crates are so crowded that new impacts destroy old craters when they make new ones; observable crater density can't go past this point; can be used to determine the age of a surface

fracture channels

when impact occurs, cracks in the crust form that are 3x the depth of the crater; magma floats up through these cracks and floods the crater (responsible for the moon's flat craters)

lithosphere

where the Earth's plates are located; heat flow and fluidity of the asthenosphere produces slow currents that drag the lithosphere fragments about; this layer is more brittle and solid