Cosmos Exam #2
Processes that shape the solid planetary surfaces
- impact cratering: impacts by asteroids or comets - tectonics: disruptions of a planet's surface by internal stresses - volcanism: eruption of molten rock onto the surface - erosion: surface changes by wind, water or ice
Impact cratering
- impactor vaporizes - can cause an explosion that results a bowl-shaped crater - most cratering happened within 1st bill years after solar system formed - craters are about 10 times wider than object that made them - small craters greatly outnumber large ones - a surface with many craters has not changed much in 3 billion years - Cratering is the most dominant process on many terrestrial bodies
Greenhouse Effect
- incoming solar energy (mostly visible light) - incoming solar energy absorbed by the surface and re-emitted at longer wavelengths (mostly IR) - outgoing long wavelength energy escapes to space and some of it is trapped, reflected, absorbed by the atmosphere of GHG - about 40% of the light never makes it to earth and is reflected back into space
Earth's Interior
Crust - Lowest density rocks (granite, basalt etc), 0-69 km thick Mantle - high density rocks. Below the crust to 2900 km Core - highest density layer 95% iron, rest mainly nickel. Outer core is liquid, inner core is solid Lithosphere - rigid layer that "floats" on warmer rock. Crust and mantle
Xenoliths
Fragments of rock that are from the crust ~300km/186 miles deep
speed of light formula
Frequency and wavelength are related by: wavelength (lambda) x frequency (v) = speed of light (c)
Volcanism (unrelated to plate tectonics)
- "hot spot" volcanism happens when molten rock (magma) finds a path through the crust to the surface - molten rock is called lava after it reaches the surface
Ceres
- Asteroid - only dwarf planet in the asteroid belt - rocky core and icy mantle - bright spots are salts from evaporated water
polar ice caps on mars
- CO2 ice covering water ice (and even sub-glacial lakes!) - ice under the surface - oxygen locked in the rust - most of atmosphere lost in space
What drives plates to move
- Convection of the mantle creates stresses in the crust called tectonic forces - Convection cells can create mountains and valleys - hot molten goes up, cold goes down - compression of crust creates mountain ranges - valley can form where crust is pulled apart
Heat transport
- Convection transports heat as hot material rises and cools material falls - conduction transfers heat from hot material to cool material - Radiation sends energy into space
Plate interaction
- Divergent - plates moving apart - Convergent - plates moving toward each other or colliding - transform - plates moving past each other (without colliding or splitting)
Jovian Questions
- How are Jovian planets all alike? - What are they like on the inside? - What is the weather like on Jovian planets?
Why do the jovian planets have rings, but the terrestrial planets do not?
- Jovian planets have many more moons - rings formed from the dust and ice created by random impacts on the moons
Calisto
- Jupiter's moon - old cratered, surface, with dirty ice, "recent" impacts exposes cleaner ice, darker areas may be dust/rock - interior never hot enough to melt ice or barely become molten, largely undifferentiated and no layering in the interior - interior is more homogenous mix of rock and ice - no core due to no tidal heating
Mars basics
- Mass 11% of E's mass - Radius 53% of E's radius - density 3930 kg/m3 - mars has an atmosphere, but has a dust storm
Uranus Basics
- Mass 14.5x earth's mass - radius 4x earth's radius - density 1290 kg/m3 - basically featureless because it's entirely covered for methane gas
Neptune basics
- Mass 17.2x earth's mass - radius 4x earth's radius - density 1660 kg/m3 - blue from methane cloud layer - storms coming and going
Saturn Basics
- Mass 95x Earth's mass - Radius 9.4x Earth's radius - Density 710kg/m3 (less dense than water) - magnetic field is 20x weaker than jupiter - belt zone circulation exists, but not as well defined because it is colder and cloud layers form deeper, below haze layer
what kind of light makes it to the ground and how much?
- Radio waves - pass straight through - IR light absorbed by atmosphere, less reaches the surface - Visible light passes straight through - UV absorbed by atmosphere, less reaches the surface - X-rays are completely blocked by atmosphere (sun doesn't give out much) - Gamma also completely blocked by atmosphere (sun doesn't give out much)
Atmosphere Absorption spectrum
- Very little absorption at visible wavelengths - Absorption of UV by ozone in upper atmosphere - Absorption of IR by greenhouse gases in lower atmosphere - water vapor and CO2 block rays from going in and out
Geological history
- Volcanoes - requires internal heat (molten interior) - Ridges of various kinds - tectonics, requires internal heat (molten interior) - Erosion - dunes (atmosphere), stream beds (flowing liquid) - impact craters - old feature: significant int he past, random events today, can be destroyed by other geological processes
Sources of Magnetic Fields
- a planet can have a magnetic field if charged particles are moving inside - Requirements: molten, electrically conducting interior, moderately rapid rotation
ring systems on other jovian planets
- all 4 jovian planets have ring systems - others have smaller, darker ring particles than saturn
jovian planets similarities
- all are fast rotaters compared to terrestrial planets - jovian planets are not quite spherical because of their rapid rotations - liquid internal - no solid surface, just core - layers under high pressure and temperatures - all of them have strong winds and storms (atmosphere) - cloud layers condense at different altitudes
Neptune and Uranus
- are smaller and have weaker magnetic fields - relatively featureless (all blue) - magnetic field caused by dissolved ions in liquid water near the surface - have single could layer of methane
interior of venus
- because Venus is similar size to Earth and has active volcanic features, it should have a similar internal structure with a partially molten interior and a liquid outer core - but odd that Venus has no MAGNETIC FIELD --- outer core is solid? --- rotation is too slow for charges to circulate in a liquid core?
Erosion
- blanket term for weather-driven process that break down or transport rock
Jupiter's storms
- brown ovals are low pressure stomrs - white ovals are high pressure storms - lots of vortexes at the top of the north pole
Venus' atmosphere
- composition mostly CO2 - 90 atm at surface (90x earth's) - humidity/water 0.002% at surface - surface temp average 870 F, which would melt lead - sulfuric acid rain
Mars' atmosphere
- composition mostly CO2 - pressure 0.006-0.01 atm at surface - water, dry (0.03% at surface) - average temp is -80F - estimated to be 10-100x thicker in the past
Size of Craters
- depends on the object that's impacting the surface, determined by the planet or moon that its impacting
Structure of Jupiter's atmosphere
- different types of hydrogen compounds form clouds in Jupiter's atmosphere - each compound produces clouds of different colors - the compounds condense at different temperatures forming cloud layers at different depths
Earthquake process
- energy is transferred by seismic waves - waves of energy travel through earth - can measure earthquake even if we are not in the location where the earthquake ocurred
Medium to large moons around jovian planets
- enough self-gravity to be spherical - have substantial amounts of ice - formation similar to the planets formation around the sun -- formed in orbit around jovian planets -- larger moons closer to the planet have less ice than more distant ones -- orbit in equatorial plane -- mostly circular orbits in same direction as planet rotation
erosional debris
- erosion can create new features such as deltas by depositing debris
Meteorites
- extraterrestrial materials that fall to earth - leftovers from solar system formation - given an indication of what elements formed the Earth - don't see much iron on the surface of the planet, so most of the iron has to bee in the interior of the planet
small moons
- far more numerous than the medium and large moons - not enough gravity to be spherical (many are potato shaped) - captured asteroids or comets, so their orbits do not follow usual patterns (backwards, largely elliptical)
Seismic waves caused by...
- faulting (plate tectonics) - volcanoes - bomb blasts - Asteroid/Meteor Impacts - Landslides
Igneous rock
- forms when molten rock (lava) cools - Implies the planet had hot, partially molten interior when the rock formed
Sedimentary rock
- forms when rocks are broken apart and pieces are "glued" back together - implies the presence of liquid (water) on the planet when the rock formed
metamorphic rock
- forms when rocks are changed due to high heat and pressure - implies that plate tectonics were active on the planet when the rocks were formed
Late Stage Bombardment
- gravity from planets disrupt orbits of planetesimals - some of the leftovers bombarded other objects in the late stages of solar system formation
mars feature
- has smooth northern hemi - cratered southern hemi - HAS NO MAGNETIC FIELD AND VERY THIN ATMOSPHERE - has shield volcanoes - has valley system is thought to originate from crust shift (tectonics) not erosion like the Grand Canyon - evidence for liquid water flowing on the martian surface. has hemitites that come in standing water. some of the craters have channels coming out of them, some of the craters are eroded by water. river deltas
Highlands on the moon
- heavily cratered - composed of jumbled mountains that were pushed up by craters - low density anorthosite - light colored
Jupiter's Great red spot
- is a storm 1.4x the size of Earth (used to be larger) - although hurrican-like, caused by high pressure systems, rather than lower pressure systems on earth - there is no land surface on jupiter, which usually stops storms
why no planet in asteroid belt
- jupiter and orbital resonances - asteroids in orbital resonance with jupiter experiences periodic nudges - if passes jupiter more frequently it feels jupiter's gravity and it gets tugged - eventually those nudges move asteroids out
Tectonics
- large-scale processes affecting the structure of the [Earth's] crust - plate tectonics (on earth) - crust is fractured into plates which float on the warm underlying layer - release heat from the hot, particularly molten interior, primarily at the late boundaries
Lowlands (aka maria) on the moon
- less cratered - composed of low lying, smooth lava flows - higher-density basalt - dark colored ignious rocks - younger by .6 billion years
Properties of light
- light is radiant energy - speed - c = 300,000 km/sec - has characteristics of both wave and a particle (treat it like a wave) - the colors are determined by WAVELENGTH of light and different colors of light have different wavelengths - FREQUENCY - how fast successive crests pass by a given point
Crustal Shrinkage on Mercury
- long cliffs indicate that mercury shrank early in its history - cooling core shrank about 20 km - occurred 1-2 billion years after formation, but geologically dead today
Visible spectrum
- long wavelengths are red - short wavelengths are blue - visible compromise about 1.5% of the total EM spectrum
Saturn rings
- made up of numerous icy particles with a trace of rock - sizes range dust, to boulder, to small moons - very thin (10 meters) and have dramatic gaps - some have that are 1-2 km high rings due to moons that tug on the rings - orbit around saturn's equator and obey kepler's 3rd law of motion - has many rings - moons are in the E-ring and ice particles from volcanoes from Enceladus
Interior of Jupiter
- magenetic field is 14x stronger than the earth's - magnetic field is much closer to the surface than the core - density contrains the rocky/metallic core to 1-10 earth masses - Equatorial radius is 6% larger than the polar radius, which means liquid interior that makes it bulge at the sides - High pressures inside Jupiter cause phase of hydrogen to change with depth - hydrogen acts like a metal at great depths because its electrons move freely - Core is thought to be made of rock, metals, and hydrogen compounds - core is about same size of 10 earth masses, but compressed down to the size of the earth
Volcanoes on Venus
- many volcanoes, including both shield volcanoes and stratovolcanoes - lava plains also evident - assume still geologically active, because sulfur dioxide in atmosphere from volcanic outgassing
Venus basics
- mass 82% of E's mass - Radius 95% of Earth's radius - Density is 5240 kg/m3
Cratering of Mercury
- mercury has a mixture of heavily cratered and smooth regions like the moon - most cratered planet - smooth regions are likely ancient lava flows - Rachmoninov crater that is 3.5 miles deep and is the deepest crater in the solar system - moon has more craters than the moon, therefore may have lots of lava fill
Magnetic field requirements:
- molten, electrically conducting interior (ex liquid metal) - moderately rapid rotation
Jupiter's atmosphere
- mostly hydrogen and helium - cloud layers where ammonium and ammonumm hydrosulfide and water vapor condense - belt zone circulation - long lived storms
Magnetic fields in Planets
- motions of charged particles are what create magnetic fields - circulating charges - A planet can have a magnetic field if charged particles are moving inside
Neptune's largest moon: Triton
- orbits backwards compared to other moons - probably captured by Neptune's gravity - has ice geysers erupting nitrogen - similar to pluto, but larger - evidence of past and current geological activity bc no cratering - has plumes that blows eroptions
Erosion on Venus
- photos of rocks taken by landers show very little erosion, - too hot for water, - not a lot to disturb it - rotation too slow for strong surface winds
Role of Distance from the Sun
- planets close to the Sun are too hot for rain, snow, ice and so have less erosion; hot planets have more difficulty retaining an atmosphere - planets far from the sun are too cold for rain, limiting erosion - planets with liquid water have the most erosion
Rotation of planetary rotation
- planets with slower rotation have less weather, less erosion, a weaker magnetic field and vise versa
Convergent boundaries
- plates running into each other - produces mountains - volcanic mountains - deep sea trenches, one of the plates going underneath the other - earthquakes
magnetic field on a planet
- prevents radiation particles from harmful radiation - protects the atmosphere from being stripped away
why not all jovian planets have rings like saturn
- rings are't leftovers from formation; they will eventually spiral into the planet after 10-100 million years - saturn has too much material to have surived from planet formatoin and the particles are too small to have survied fro so long; mass of the rings is half of the moon mimas - must be continuous replacement of tiny particles or the rings are "recent" formation
geology on rocky planets versus icy moons
- rock melts at higher temperatures - ice melts at lower temperatures - only large rocky planets have enough heat for activity - tidal heating provides continuing energy, melt internal ice, driving activity
Asteroid facts
- rocky stuff of planet left over from the solar system formation - largest is Ceres (dwarf planet) - 150k in catalogs, and probably more than 1 million with a diameter under 1 km - small asteriods are more common than larger ones - all asteroids in the solar system wouldn't add up to even a small terrestrial planet ~4% of our moon - asteroids are black as charcol - asteroids are cratered and too small to be round
Types of Lava and Volcanoes
- runny lava makes flat plains and fills in - slightly thicker lava makes shield volcanoes - Thickest lava makes steep stratovolcanoes - the higher the density of the rock, the higher the temperature needed to melt the rock
Seafloor spreading/recycling
- seafloor crust is thinner and denser than continental curst - seafloor quite young compared to continents - fewer sea floor craters - seafloor crust is created by divergent ridges and recycled through subduction - CONTINENTS DO NOT GET RECYCLED because will maintain ground longer
Possible history of venus
- similar to earth, but brightening of the sun causes venus to be too warm for liquid water, triggers runaway greenhouse effect - maybe periodic planetwide crust resurfacing
bennu asteroid
- small, near earth asteroid - fragment of a larger asteroid broken up after an impact - rich in volatiles and carbon compounds - thought to have seeded earth with organics - idea was to capture an uncontaminated sample and return to earth - but the surface is very rocky and bolder strewn than expected - when volatiles exposed to sun explode -
Role of Size in Cooling
- smaller worlds cool off faster and harden earlier - the moon and mercury are considered geologically "dead" meaning no internal heat, and also no atmospheres - larger worlds remain warm inside, promoting volcanism and/or tectonics - larger worlds also have more erosion because their gravity retains an atmosphere
surface of Venus
- smooth, rolling lava plains - deformed highlands (tessera) that are formed - unlike the moon and mercury - no ancient plains bc no cratering
Asteroids with moons
- some larg asteroids have their own moon - helps us measure mass of composition and density - some asteroids are solid as rock - others are just piles of rubble
where did water on Mars go?
- some under polar ice caps - under glaciers - permafrost
Tidal Heating
- strength of gravity is different between farside of the moon and nearside of the moon - nearside of the moon is closer to the planet and has a stronger force than the farside, which pulls the moon - with an elliptical orbit, when the moon is at the farthest location from the planet it becomes more circular, and as it gets closer to the planet it becomes more oblong - therefore, the moon is stretching and relaxing, which heats the interior and generates geological activity - the more elliptical the orbit, the more drastic the changes in the moon shape and stretching - circular orbit does not have tidal force
Ring formation
- stress of tidal forces can shatter the moon with saturn's gravity - the mini moons going around the planet being hit by other material that breaks them up
Determining age of planet surface
- the surface with fewer craters was modified more recently than the one with more craters - the surface with fewer craters is younger than the surface with more craters - determining the CRATERING RATE
Io, Europa, and Ganymede relationship
- they all are being tugged on by Jupiter and each other - every 7 days, these 3 moons line up - the tugs add up over time, making all 3 orbits elliptical - 4th moon callisto is too far to be affected by Jupiter or other three moons much - all have a core, mantle of rock, and ice - Io only has core and mantle
divergent plate boundaries
- usually in the middle of the ocean - produces new ocean floor - underwater volcanism - earthquakes
Medium moons on Uranus
- varying amounts of geological activity - miranda has large (tectonic) fractures and few craters
cratering on venus
- venus has far fewer impact craters than moon and mercury: age of surface is very young - amount of cratering is uniformly over the surface, the surface is all the same age - the entire surface is ~500 mill yo, which is significantly younger than other terrestrial planets
Volcanic Outgassing
- volcanism also releases gases from planet's interior into the atmosphere
Divergent ridges
- where crust spreads indicating plate tectonics can occur either on the sea floors or continents - motion of the continents can be measured with GPS, with a few centimeters a year
Crater sequencing
- younger crater on top, older on the bottom - ejecta rays count as part of the crater - crater with rays is not necessarily the younger one - if they don't overlap, we're out of luck
Three types of rock
1. Igneous 2. Sedimentary 3. Metamorphic
newton's law of gravity: a primer
1. attractive force between all masses: every mass attracts every other mass 2. Strength of attraction is DIRECTLY proportional to the product of their masses 3. strength of force decreases with distance - everything pulls on everything else - the larger the masses, the greater the pull - objects close together pull more on each other than objects farther apart
Lunar evolution
1. formation of highland crust: 4.6-4.1 billion years ago 2. Period of heavy bombardment: 4.1-3.8 billion years; late heavy bombardment 3. formation of the maria: ~4-2 billion years ago - Early surface is covered with craters - large impact crater weakens crust - heat build-up allows lava to well up to surface - cooled lava is smoother and darker than surroundings
Any moon theory must naturally explain:
1. moon's orbital tilt (5 degrees tilted from Earth's orbit) and eccentricity (0.055) 2. the moon's lower density - lack of a substantial iron core like the earth does 3. rocks from the Apollo mission show a lack of trapped gases and water (volatiles) compared with Earth and asteroids 4. rocks also show some isotopes having same proportions as Earth - indicating local origin
Light travel and absorption process
1. sunlight arrives at the Earth 2. some of the sunlight is reflected by clouds and the surface 3. sunlight that is not reflected is absorbed by surface, heating it 4. heated surface emits infrared radiation 5. some of the IR radiation is trapped by atmosphere, heating both the atmosphere and the surface 6. remaining IR radiation leaks into space, but it will take longer the more GHG you have the warmer surface you have
Amount of incoming sunlight
342 Watts over every square meter - heat does not build, add numbers up should get 342 Watts - incoming solar energy, mostly VISIBLE gets to the ground, which is a source of heating - other source of heating is the INFRARED light or heat we get from the atmosphere - GH effect is a natural process and the surface of the Earth would be much colder without the GHE
History of mars 3rd period
Amazonian period - 1.8 bill ya to present - thin, cold atmosphere - cooled interior - no volcanic activity, no magnetic field - dominated by wind erosion and meteorite impacts
types of Seismic Waves
Body Waves and Surface Waves
Greenhouse Gases
CO2, methane, water vapor - gases are the reason for the GHG effect - absorb different wavelengths of light - ex: CO2, visible light will go through CO2, but IR would absorbs and re-emit the gas in any different direction
Material's densities***
Can indicate proportions of rock, metals, etc in a planet - Ice and gas ~1000 km/m3 - Rock ~3000 km/m3 - Metal ~8000 km/m3
What causes geological activity
Caused by planet's internal heat
Density
Density = mass/volume - how compact the material is - gas is less dense, liquid more, solid are more - density does not depend on size of the matter, only material that makes up the object
Transform boundaries
Earthquakes - dont' slide by each other very easily - pressure builds up and pressure is released
the electromagnetic spectrum (increasing wavelength)
Gamma rays, X-rays, ultra-violet light, visible light, infrared, microwaves, radio waves
Seismic Waves
Have provided the most information about the Earth's deep interior Earthquakes - sudden release of energy and the subsequent shaking of the ground
History of Mars 2nd period
Hesperian Period - 3.5-1.8 Billion years ago - interior cools, whic means volcanic activity slowly decreases, less outgassing, magnetic field dies, atmosphere thins from loss to space, surface cools - northern plains date from this period and the next period
Saturn Pole oddity
Hexagonal cloud pattern around the north pole of Saturn - cloud form from turbulence between two cloud bands of very different speeds - poles go thru different seasons - winter is bluer with methane gas condensation
Age of Planetary surface
Last time it was significantly changed - not necessarily when the surface was formed - by volcanism, wind and/or water activity, plate tectonics - basically anything that erases surface features and forms new rock
Moon basics
Mass - 1% of Earth's mass Radius - 27% of Earth's radius Density - 3340 kg/m3
Mercury Basics
Mass - 5.5% of Earth's Mass Radius - 38% of Earth's radius Density - 5430 kg/m3 Mercury is slow rotator - rotates once and 59 days, but orbits once every 8 days
Jupiter basics
Mass 318x Earth's mass Radius 11.2 x earth's radius Density is 1330 kg/m3
Moon today
Moon is geologically dead because geological processes have virtually stopped
Mars Topography
N hemisphere - low elevations S hemisphere - high elevations
Orbital resonances
Over time the gravitational tugs of outer bodies add up creating resonances * similar to a series of small pushes on a child swing
Proceeding down inside Jupiter
Pressure and temperature are beyond the hydrogen CRITICAL POINT, when hydrogen is under such pressure that it starts to look like a liquid - there is no clear distinction between liquid and gas states - atmosphere around you GRADUALLY increases in density until you are a liquid A quarter of the way down hydrogen turns into liquid metallic hydrogen, charges can go through it - electrons are able to move freely like in a metal, rather than a molten metal, this provides the source of the magnetic field - the center is 5-6x hotter than the sun's surface - core is sloshing around in the middle and may be dissolving
Capture Hypothesis Pros and Cons
Pros - it's possible - jovian planets have done so - Explains why moon is large compared to Earth Cons - difficult to slow moon to capture without impact - predicts orbit should be ecliptic (it's tilted by 5 degrees) and much more elliptical - compositions should be similar to large asteroids (density ~2100 kg/m3) and contain volatiles (trapped gases), but the moon rocks are missing these volatiles (baked out)
Fission Hypothesis Pros and Cons
Pros: - Density of moon similar to that of the outer layers of the Earth Cons: - difficult to explain the size of the moon - Earth would have to have been spinning very fast - moon should be orbiting above the earth's equator; its not - volatile problem still exists
Impact hypothesis pros and cons
Pros: - collisions happen (but this is a whopper: Mars sized or bigger!) - explains lack of volatiles in the moon, they're baked out, when planet hit the earth it would give oportunity for trapped gases to escape - explains lack of iron core - portion merged with Earth's (merge might explain some composition similarities too) - density is similar to the Earth's curst and mantle cons: - Not easy to eject material far enough away to coalesce into an object without falling back to Earth - Predicts reformed moon orbiting above Earth's equator (again, it's not) - Why only one moon?
Binary Accretion Pros and Cons
Pros: - lots of material in early solar System to accrete (how Jovian planets formed moons) Cons: - predicts Earth and Moon with same densities (moon is actually iron deficient) and composition (volatiles should be missing) - Moon would be orbiting above the EArth's equator (it's not)
Seismometers
Records ground motion overtime - the record of waves is a seismogram
Titan
Saturn's largest moon and only large moon - the only moon that has a permanent atmosphere around it - has a thick, opaque atmosphere rich in Nitrogen - has liquid at the north pole of liquid methane - there is weather on titan caused by methane clouds, rain, rivers, and oceans - rocks made of ice that were weathered and smooth
Geological processes on Jovian moons
Similar to those on terrestrial planets - impact cratering - volcanism - erosion from wind and ice (ice can be other substances than water) However, so far no evidence of: - tectonics - (liquid) water erosion Some processes in operation on Jovian moons but not on terrestrial worlds - strong tidal forces can heat and melt the interior of the moon
History of Mars 1st period
The Noachian Period - formation 3.5 billion years ago - thicker, warmer atmosphere with rivers, lakes, oceans - hotter interior, which means abundant volcanic activity and a MAGNETIC FIELD Southern Hemi dates from this period
Body Waves
Travel through the Earth's interior - P-waves and S-waves
Meteor
a bright trail in the sky from a meteorite once it hits the atmosphere - doesn't necessarily make it to the ground
metiorite
a rock from space taht falls through the earth's atmosphere eventually hits the ground - most meteorites originated in Asteroid belt
important point about objects and light
all objects (solid, liquid, gas) reflect, absorb, and emit EM radiation, BUT they do so at different wavelengths that depends on their composition
Medium moons on saturn
almost all of them show evidence of past volcanism and or tectonics Enceladus: has tidal heating, very large geiser, stripes due to geiser craters on only one side Iapetus: odd equatorial ridge, dramatic "two-tone" color Pan: small moon, orbits with rings, pulls materials off of them
Differentiation
causes the planet to go from being homogenous and well mixed to being layered by density - while planet is molten, differentiation will occur - Gravity pulls high-density material to center - lower-density material rises to surface
Hollows
collapsed crater floor created by escaping gases - no cratering, relatively new surface
Mars crust
crust is thicker than earth's - has marsquakes that last a long time, but are very mild - outer core is still liquid - core is much bigger than thought - thinner mantle leads to more rapid cooling - core is less dense than thought - not hot enough for active volcanoes
Moon crust
crust on the farside is 30 miles thicker than the nearside of the moon - more maria on the nearside because it's thinner
energy carried by light
different colors of light have different amounts of energy - red has less energy than blue
Continental motion
fossil records indicate that animals could walk across - mantle material erupts where seafloor spreads
Processes that cause erosion include:
glaciers, rivers, wind
Ganymede
jupiter's largest moon - largest moon in the solar system - clear evidence of geological activity from tidal heating - 3 mile deep ocean lying about 110 miles below the surface
Io
jupiter's moon - most dense of the moons - has the most tidal heating - most volcanically active body in the solar system (including earth) - driest place in the solar system, because tidal heating effectively boiled off all the water - tidal forces cause the surface to rise and fall by 330 feet each orbit (1.8 days) - surface has not impact craters - frequent eruptions
Europa
jupiter's moon - no dark, dirty terrain - entire surface is young - 100 mile deep ocean lying about 10 miles below the surface which means melting of ice - cracks are caused by tidal stressing - bluish-white areas are relatively uncontaminated water ice - brown areas could be brown salts
Caloris basin on Mercury
largest impact crater on mercury - such a violent collision that it jumbled the surface on the other side
Cratering and Lava flow
lava flows can give us a sequence of events - lava flowed early in moon's history while interior was still molten - impacts fractured surface allowing lava flows - after moon cools, craters no longer filled w/th lava - when there is lava flow with separated craters, lava flow indicates the older crater - crater can go on top of another feature
P waves
primary waves - push and pull - fastest waves and therefore arrive first - travel through SOLIDs and LIQUIDS
S waves
secondary waves - shake side to side or up and down - 2nd fastest, so arrive after p-waves. can calculate distance by how long after the S-waves arrive after the P-waves - travel ONLY through SOLIDS
Terrestrial Planet interiors
since terrestrial planets formed similarly other planets interiors are probably like the Earth's
Processed meteorite
slightly younger; have experienced processed like volcanism or differentiation - some form of heat applied to this - made of iron and other metals that came from a shattered asteroid's core - processed material that came from the mantle
"sheperd moons
small moons can force particles into a narrow rings
Gap moons in saturn
some small moons create gaps within rings
What kind of light does the sun give off?
sun radiates mostly visible and infrared light, as well as a small amount in UV sunlight - UV: 7% - visible: 44% - Infrared 48%
energy transfer on Earth
the Amount of energy absorbed by Earth from the Sun is equal to the amount of energy given off by Earth
Shadow Zones
the area where waves do not reach on the planet - Can get size of the core based on the shadow zone - the bigger the core, the bigger the shadow zone - the smaller the core, the smaller the shadow zone
Capture hypothesis
the moon formed elsewhere (asteroid), drifted too close to the earth and was captured
Giant impact theory
the moon formed from material thrown off during a large impact event
Fission Hypothesis
the moon formed when the earth broke up because it was spinning too fast
Binary Accretion
the moon formed with the Earth from the same cloud of debris at the same time
ejecta blanket
the ring of material surrounding a crater that was ejected during the crater-forming impact
Surface Waves
travel through layers near the earth's surface - can go across the entire map
Primitive Meteorite
unchanged in composition since they first formed 4.6 bill ya - made of rocky material embedded with shiny metal flakes -
Vesta
walnut shaped asteroid
White light
white light could be split into component colors with a prisim - and then recombined into white light with a lense - white light is a composite of all colored lights
Sizes of moons
• Small moons (< 300 km) — No geological activity • Medium-sized moons (300-1500 km) — Geological activity IN THE PAST • Large moons (> 1500 km) — ONGOING geological activity
