Cosmos Exam #2

Inside Jupiter

Core is thought to be made of rock, metals, and hydrogen compounds. Core is about same size as Earth but up to 10 times as massive.

Cratering

Cratering is the dominant process on many terrestrial bodies

Why does the farside lack the Maria of the nearside?

Crust on farside is 30 miles thicker

Earth's Interior

Crust: lowest density rocks - granite, basalt, etc. 0-60 km thick (30 km on average) Mantle: High density rocks Below the crust to 2900km 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 + Mantle

Basic Properties: Frequency

Frequency -how fast successive crests pass by a given point - denoted by the Greek letter "nu" v Measured in Hertz (Hz)=1 cycle/sec Frequency and wavelength arerelatedby: λ*ν=c 'c' is the speed of light.

Jovian Aurorae

how auroras form: - coronal mass ejection - energetic particles stream outward - are caught in magnetic field - causing atmospheric gases to glow

Magnetic Fields

A planet can have a magnetic field if charged particles are moving inside. Requirements: Molten, electrically conducting interior (i.e. liquid metal) Moderately rapid rotation

Ring Systems on other Jovian Planets

All four Jovian planets have ring systems . Others have smaller, darker ring particles than Saturn.

Jupiter's Colors

Ammonium sulfide clouds (NH4SH) reflect red/brown. Ammonia, the highest, coldest layer, reflects yellowish-white.

Cratering on Venus

Amount of cratering is fairly uniform over the surface Entire surface approx. same age Venus has far fewer impact craters than the Moon or Mercury. Age of the surface is very young The entire surface is ~500 million years old

Interior of Venus

Because Venus is similar in size to the 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, and if so, why? - or - Or slow rotation (243 Earth days) is too slow for charges to circulate in a liquid core. Unclear how thisworks (or doesn't)

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

Plates interact with each other at their boundaries:

Divergent - plates moving apart Convergent - plates moving toward each other or colliding Transform - plates moving past each other (without colliding or splitting)

Earth's surface shaped by plate tectonics

Divergent Ridges - where crust spreads indicating plate tectonics - can occur either on sea floors or continents Motion of the continents can be measured with GPS - few cm/yr.

Medium to Large Moons

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 Large 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

Earthquake - Sudden release of energy and the subsequent shaking of the ground

Faulting (plate tectonics) Volcanoes Bomb blasts Asteroid/Meteor Impacts Land slides

Erosion by Ice

Glaciers carved the Yosemite Valley

Tidal Heating & Orbital Resonances

Io, Europa & Ganymede are being tugged by Jupiter and each other Every 7 days, these three moons line up. The tugs add up over time, making all three orbits elliptical. 4th moon, Callisto, is too far to be affected much by Jupiter & other 3

Jupiter's Great Red Spot

Is a storm twice as wide as Earth 1.4 X Although hurricane-like, caused by high pressure systems, rather than low pressure systems on Earth

Ring Formation

Jovian planets all have rings because they possess many small moons close in. Impacts on these moons or collisions with each other are random. Saturn's extensive ring system may be an "accident" of our time.

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 - core and mantle shrank - causing mercury's crust to contract and crust were forced to slide under others - due to this crustal movement we see steep cliffs

Clues the interior: What lies beneath

Magnetic field is 14 times stronger than the Earth's at it's "surface" Density constrains the rocky/metallic core to 1-10 Earth masses Oblateness implies a largely liquid interior Mathematical models give us an idea of how this all fits together Equatorial radius is 6% larger than the polar radius

Comparing Jovian Interiors

Models suggest cores of Jovian planets have similar composition. Saturn has similar internal structure but lower mass and lower internal pressure means layers are in different proportions Even smaller masses for Uranus and Neptune mean no metallic hydrogen due to even lower pressures inside Weak magnetic fields as a result - caused by dissolved ions in liquid water near the surface

Io

Most volcanically active body in the solar system (including Earth!) Driest place in the solar system: tidal heating effectively boiled off all water - gas plumes created from hot lava over sulfur dioxide frost Tides cause the surface to rise and fall by 330 feet each orbit (1.8 days) Surface has no impact craters - frequent eruptions

Surface Features

Mountains form formed from collision between plates. The Himalayas The Red Sea is formed where plates are pulling apart.

IapetusMedium Moons of Saturn

Odd equatorial ridge dramatic 'two-tone' coloration

Triton - Neptune's largest moon

Orbits "backwards" compared to other moons - probably captured by Neptune's gravity Has ice geysers erupting nitrogen (cryovolcanism)

Neptune's Moon Triton

Orbits backwards - captured from KB? Similar to Pluto, but larger Evidence of past geological activity - lava filled impact basins - lava was water or slush Triton - wind because of plumes moving in same direction

Role of Distance from 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.

Role of Planetary Rotation

Planets with slower rotation have less weather, less erosion, and a weak magnetic field. Planets with faster rotation have more weather, more erosion, and a stronger magnetic field.

Other Evidence of Water Flows - Erosion of Craters

Pressure and temperature must have been favorable for large scale water flows in the past - though not today Details of some craters suggest they were once filled with water.

Heat Transport The Cooling of Planetary Interiors

- Convection transports heat as hot material rises and cool material falls. - Conduction transfers heat from hot material to cool material. - Radiation sends energy into space.

Seismometers

Records ground motion over time The record of waves is a Seismogram

Then why don't all the Jovian planets have rings like Saturn's?

Rings will eventually spiral into the planet after 10-100 million years Saturn has too much material to have survived since planet formation and the particles are too small to have survived for so long. Mass of the rings is half of the moon Mimas (based on Cassini's published March 2019) Ice particle would appear darker if very old (billions rather than millions of years) Must be a continuous replacement of tiny particles or the rings are "recent" formation

Geology on Rocky Planets versus Icy Moons

Rock melts at higher temperatures. Only large rocky planets have enough heat for activity. Ice melts at lower temperatures. Tidal heating provides continuingenergy, melt internal ice, driving activity.

Seafloor Spreading/Recycling

Seafloor crust: thinner (5-10 km) & denser than continental crust (20-70 km). Seafloor quite young compared to continents - fewer sea floor craters Seafloor crust is created at divergent ridges and recycled through subduction - replaced after 200 Million years; Continental crust isn't recycled connection cell - hotter molten material rises and cooler falls

Rifts, Faults, Earthquakes

Sliding motion of plates can cause earthquakes. Motion between plates isn't smooth, rough edges catch San Andreas fault in California is a plate boundary.

Role of Size in Cooling

Smaller worlds cool off faster and harden earlier. The Moon and Mercury are now geologically "dead." No internal heat (also no atmospheres - more later)

Role of Planetary Size

Smaller worlds cool off faster and harden earlier. Larger worlds remain warm inside, promoting volcanism and/or tectonics. Larger worlds also have more erosion because their gravity retains an atmosphere.

Understanding the Greenhouse Effect

Spectra for Sun and EarthSun gives of mostly visible & IR, some UV; Earth gives of mostly IR & reflects visible Greenhouse gases absorb and re-emit IR but are transparent to Visible light. H20, CO2, CH4 Surface of planet is heated by energy (light) from the Sun AND from energy (IR light) re-radiated from the atmosphere GHE effect is a natural process and the surface of Earth would be much colder w/out GHE

More Evidence of Flowing Water

Spirit and Opportunity rovers have found "blueberry" rocks - hematite - that appear to have formed in water.

If you know the cratering rate, you can get the numerical age

Suppose craters formed on both these areas at a rate of 1 crater per million years. How old are these areas? Left side: 9 Million (9 craters) years Right side: 3 Million years (3 craters)

Need rock samples to constrain cratering rate

Suppose radiometric dating shows surface on the left is 3 million years old. What is the cratering rate? What is the age of the surface on the right?

Hot Spots

The Hawaiian islands have formed where a plate is moving over a volcanic hot spot - a plume from the mantle.

Basic Properties: Wavelength

The colors are determined by the wavelength of light - Denoted by the Greek letter "lambda" Visible light measured in: Micron (μm) - 10-6m Nanometer (nm) - 10-9m Angstrom (Å) - 10-10m

Valles Marineris

The system of valleys is thought to originate from crust shift (tectonics?) not erosion like the Grand Canyon

Possible History of Venus

Venus starts outgassing a thick, carbon dioxide rich (secondary) atmosphere. Most likely had liquid water on surface, too Brightening of the Sun causes Venus to be too warm for liquid water to stay, triggers runaway greenhouse effect Next 4 Billion years ??????????????????????? Periodic, planet-wide overturning of crust? Or did Venus have plate tectonics like the Earth until a recent, single resurfacing event Why no plate tectonics now? How did the tessera form?

Medium Moons of Uranus

varying amounts of geological activity. Miranda has large tectonic features and few craters (tidal heating in past?)

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. hot spot volcanism examples: Hawaii and lo

Rotation and Shape

- All rotate much faster than terrestrial planets - Jovian planets are not quite spherical because of their rapid rotation - wider at equator

Cratering of Mercury

- Caloris Basin is largest impact crater on Mercury - Hollows - collapsed crater floor created by escaping gases

Early planets were hot!

- Heat generated from impacts - Heat generated by short-lived radioactive elements - early planets = both types are very hot

Moon Basics

- Mass = 7.35 x 1022 kg (~1% of Earth's mass) - Radius= 1737 km (27% of Earth's radius) - Density = 3340 kg/m3 (for comparison Earth is 5510 kg/m3)

More Evidence of Flowing Water Sedimentary Layers

- ancient streams, dunes and groundwater

Mars Atmosphere

- composition: mostly CO2 - pressure: .006-.01 atm at surface (lower pressure) - water: dry (.03% at surface) - surface temperature (average is 80 degrees)

Interior of Mars

- core - mantly - crust

Craters give us a sequence of events

- crater on top is younger than the one on the bottom - but a crater with rays is not necessarily the younger one - visible ejecta rays count as part of the crater - if they don't overlap, we're out of luck

How does the energy from earthquakes travel through the Earth?

- energy is transferred by seismic waves - waves of energy travel which through Earth

Impact Craters on Earth

- meteor crater in arizona

Number of craters gives the relative age of the surface

- more craters = older surface Number of craters gives the relative age of the surface, more craters = older The surface with fewer craters was modified more recently than the on with more craters The surface with fewer craters is younger than the surface with more craters.

Surface of Mars

- northern hemisphere: smooth, young plains - Southern Hemisphere: cratered highlands - shield volcanoes and valleys marineris

Major geological features of North America are a record of the history of plate tectonics.

- notes

Europa's interior warmed by tidal heating.

- ocean under an icy crust - rising plumes of warm water may sometimes create lakes within the ice, causing the crust above to crack - explaining surface terrain that looks like a jumble of icebergs suspended in a place where liquid or slushy water froze

Evidence for liquid water flowing on the Martian surface

- outflow channels - stream valleys - river deltas

Where did the water go?

- polar ice caps - glaciers - Phoenix Mission

Rings

- rings are very thin - 10 meters - but some parts can be 1-2 km high

Crater Dating

- sequence: bottom crater, lava infilling, then top - can assume the lava infilling occurred at the same time - overlap rule applies to other features - sequence: top left, lava infilling then lower right

Craters give us a sequence of events

- sequence: bottom crater, lava infilling, then top - 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 cooled, craters no longer filled with lava

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

Lunar Evolution:

1. Formation of highland crust: 4.6-4.1 billion years ago - lunar magma ocean? 2. Period of heavy bombardment: 4.1-3.8 billion years ago 3. Formation of maria: 3.8-1 billion years ago (lava surfaces and cooled lava is smoother and darker than surroundings and fills in craters) - impact craters weaken crust allowing lava to go to surface

Types of Lava and Volcanoes

1. runny lava makes flat lava plains (moon) 2. slightly thicker lava makes brand shield volcanoes (mars) 3. thickest lava makes steep stratovolcanoes (earth) density and temperatures increases from 3 to 1

The Amazonian Period

1.8 billion years ago to present Thin, cold atmosphere Cooled interior - no volcanic activity, no magnetic field Dominated by wind erosion and meteorite impacts

Continental Motion

1912: Original idea of continental drift was inspired by the puzzle-like fit of the continents. In 1950s: Mantle material erupts where the seafloor spreads Rate = ~2 cm/yr

The Hesperian Period

3.5 - 1.8 billion years ago Interior cools 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

Erosion from Stream Beds

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Why are small icy moons more geologically active than small rocky planets?

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Similar to Jupiter but...

About 1/3 as massive Magnetic field 20 times weaker Belt-zone circulation but not as well defined - Saturn is colder and cloud layers form deeper, below haze layer

Other Magnetospheres

All Jovian planets have substantial magnetospheres, but Jupiter's is the largest by far.

Important Point!

All objects (solid, liquid, gas) absorb and emit EM radiation, but they do so at different wavelengths

Medium Moons of Saturn

Almost all of them show evidence of past volcanism and/or crustal fracturing.

Energy Flow through Atmosphere

Amount of incoming sunlight: 342 Watts over every square meter incoming = out coming

Which hypothesis makes the most sense?

Any theory must naturally explain: Moon's orbital tilt (5 degrees tilted from Earth's orbit) and eccentricity (0.055) The Moon's lower density - lack of a substantial iron core like the Earth does Rocks from Apollo missions show a lack of trapped gases and water (volatiles) compared with Earth and asteroids Rocks also show some isotopes having same proportions as Earth - indicating local origin

What have we learned?

Are jovian planets all alike?Jupiter and Saturn are mostly H and He gas. Uranus and Neptune are mostly H compounds. What are jovian planets like on the inside? Layered interiors with very high pressure and cores made of rock, metals, and hydrogen compounds Very high pressure in Jupiter and Saturn can produce metallic hydrogen.

Which hypothesis makes the most sense?

Binary Accretion 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 Earth's equator (it's not).

Where did the Moon come from?

Binary Accretion - The moon formed with the Earth from the same could of debris at the same time Capture - The moon formed elsewhere (asteroid), drifted too close to the Earth and was captured Fission - The moon formed when the Earth broke up because it was spinning too fast Giant Impact - The moon formed from material thrown off during a large impact event

Difference between Uranus and Neptune to Jupiter and Saturn

Blue color caused by methane clouds (CH4) Relatively featureless (one cloud layer) but still have windy turbulent atmospheres Much weaker magnetic fields - 75% and 50% or Earth's - clue about the interior

Impact Craters

CAUSED BY SOLAR SYSTEM DEBRIS HITTING A PLANET'S SURFACE

Which hypothesis makes the most sense?

Capture hypothesis Pros: Possible - Jovian planets have done so Explains why moon is large compared to Earth Cons: Difficult to slow moon to capture w/o impact Predicts orbit should be in the 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 moon rocks are missing these volatiles (baked out)

More info

Cloud layers in other Jovian are similar to Jupiter's but condense at different altitudes. Uranus and Neptune have a single could layer of methane so we don't see the same banded structure, although they have the same zonal wind flows

Methane on Uranus and Neptune

Cold methane gas absorbs red light but transmits blue light. Blue light reflects off methane clouds, making those planets look blue.

More info

Density = mass/ volume Can indicate the proportions of rock, metals etc in a planet Ice and gas ~ 1000 kg/m3 Rock ~ 3000 kg/m3 Metal ~ 8000 kg/m3

Callisto: An old surface

Density: 1800 kg/m3 Old cratered surface Dirty Ice "Recent" impacts exposes cleaner ice Darker areas may be dust/rock leftover after surface ice sublimates ice/rock mixture - no core

What are the major geological features of Mars?

Differences in cratering across surface Giant shield volcanoes Evidence of tectonic activity

Basic Properties: Energy Carried by Light

Different colors of light have different amounts of energy E=hXv = (hXc)/lambda h is Planck's constant

Differentiation

Differentiation causes the planets to go from being homogenous and well mixed to being layered by density While planet is mostly molten, material separates by density: Gravity pulls high- density material to center. Lower-density material rises to surface. - all materials well mixed and then separated by density

Erosion

Erosion - blanket term for weather-driven processes that break down or transport rock. Processes that cause erosion include: glaciers rivers wind

Erosional Debris

Erosion can create new features such as deltas by depositing debris.

Mars' Atmosphere

Estimated to be 10-100 times thicker in the past Where did it go? Polar caps - carbon dioxide ice covering water ice Ice under the surface Oxygen locked in rust Lost to space

Consider a Class of Astronomy students as Seen in Different Wavelengths of Light!

False color coded Red - brightest Blue - dimmest

Small Moons

Far more numerous than the medium and large moons. Not enough gravity to be spherical: e.g. many are "potato-shaped" Captured asteroids or comets, so their orbits do not follow usual patterns.

Tidal stresses crack Europa's surface ice.

Few impact craters - young surface Melts the ice about 10 km below the surface

Which hypothesis makes the most sense?

Fission hypothesis Pros: Density of Moon similar to that of the outer layers of the Earth Cons: Difficult to explain size of the Moon Earth would have to have been spinning extremely fast Moon should be orbiting above Earth's equator; it's not. Volatile problem still exists

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 the pieces are "glued" back together again Implies the presence of a 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

The Greenhouse Effect

Greenhouse gases in Earth's atmosphere keep infrared radiation from rapidly escaping into space 1. sunlight arrives at the earth 2. 39% of sunlight is reflected by clouds and surface 3. sunlight that is not reflect is absorbed by surface, heating it 4. heated surface emits infrared radiation 5. some of infrared radiation is trapped by atmosphere, heating both atmosphere and surface... but will eventually escape 6. remaining infrared radiation leaks into space

Interaction of Light and the Atmosphere

Greenhouse gases: CO2, CH4, H20+ others Absorb different wavelengths of light Transparent to visible light Absorb and re-emit IR

Highlands

Heavily cratered Composed of jumbled mountains that were pushed up by craters Low density anorthosite Light colored

But something odd on Saturn

Hexagonal cloud pattern around the north pole of Saturn Could form from turbulence between two cloud bands of very different speeds

Inside Jupiter

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. - top of Jupiter: cloudtops gaseous hydrogen liquid hydrogen metallic hydrogen core or rock, metals and hydrogen compounds - pressure increases and temperature as go toward core

Three types of Rock

Igneous Sedimentary Metamorphic

What processes shape (solid) planetary surfaces?

Impact cratering Impacts by asteroids or comets Tectonics Disruption of a planet's surface by internal stresses Volcanism Eruption of molten rock onto surface Erosion Surface changes by wind, water, or ice

Which hypothesis makes the most sense?

Impact hypothesis Pros: Collisions happen (but this is a whopper: Mars sized or bigger!) Explains lack of volatiles in Moon - baked out Explains lack of an Iron core - portion merged with Earth's (merge might explain some composition similarities too) Density is similar to the Earth's crust & mantle Bonus: explains tip of the Earth's axis and rotation rate! Cons: Not easy to eject material far enough away to coalesce into an object with out falling back to Earth Predicts reformed moon orbiting above Earth's equator (again, it's not) Why only one moon?

Greenhouse Effect In a nutshell

Incoming solar energy Incoming solar energy absorbed by the surface and re-emitted at longer wavelengths Outgoing long wavelength energy is trapped by the greenhouse

greenhouse effect

Incoming solar energy Incoming solar energy absorbed by the surface and re-emitted at longer wavelengths Outgoing long wavelength energy is trapped by the greenhouse gases

Greenhouse Effect In a nutshell

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

Jovian Planet Composition

Jupiter and Saturn Mostly H and He gas Some rock in the core Uranus and Neptune Mostly hydrogen compounds: water (H2O), methane (CH4), ammonia (NH3) Some H, He, and some rock in the core

Jupiter's Magnetosphere

Jupiter's strong magnetic field gives it an enormous magnetosphere.

Ganymede

Largest moon in the solar system Clear evidence of geological activity from tidal heating 3 mile deep ocean lying about 110 miles below surface dark, old terrain - old terrain, heavily cratered & bright, young terrain - few craters

"Age" of Planetary Surface

Last time it was significantly changed By volcanism, wind and/or water activity, plate tectonics, etc. Basically anything that erases surface features and forms new rock

Lowlands (aka maria)

Less cratered Composed of low lying, smooth lava flows Higher-density basalt Dark colored

Plate Motions

Measurements tell us past and future layout of the continents.

Rings-n-Things®: Saturn

Made up of numerous icy particles with a trace of rock Sizes range dust-boulder-small moons very thin and have dramatic gaps orbit around Saturn's equator.

Was Earth's geology destined from birth?

Many of Earth's features are determined by its size, distance from Sun, and rotation rate. The reason for plate tectonics is still a mystery.

Earth's Destiny

Many of Earth's features are determined by its size, rotation, and distance from Sun. The reason for plate tectonics is not yet clear. - lot of volcanic activity on earth, Venus and sort of on mars

Volcanoes on Venus

Many volcanoes, including both shield volcanoes and stratovolcanoes. Lava plains also evident Assume still geologically active sulfur dioxide in atmosphere from volcanic outgassing

Missions to Mercury

Mariner 10: (1974-1975) three flybys photograph roughly half of Mercury's surface. Earth-based radar: (1991) signs of ice locked in permanently shadowed areas of craters in polar regions. MESSENGER: 2 phases (2008-2009) three flyby observe Mercury (2011-2015) begins its orbital mission, imaging and compositional data (analysis in progress)

Neptune Basics

Mass = 1.03 x 1026 kg (17.2 times Earth's mass; 5.4% of Jupiter's mass )Radius= 24,750 km (4 times Earth's radius) Density = 1660 kg/m3 (Jupiter's is 1330 kg/m3)

Jupiter Basics

Mass = 1.9 x 1027 kg (318 times Earth's mass) Radius= 71,500 km (11.2 times Earth's radius) Density = 1330 kg/m3 (for comparison Earth is 5510 kg/m3)

Mercury Basics

Mass = 3.3 x 1023 kg (5.5% of Earth's mass) Radius= 2440 km (38% of Earth's radius) Density = 5430 kg/m3 (for comparison Earth is 5510 kg/m3)

Venus Basics: Earth's (evil) Twin?

Mass = 4.87 x 1024 kg (~82% of Earth's mass) Radius= 6000 km (~95% of Earth's radius) Density = 5240 kg/m3 (for comparison Earth is 5510 kg/m3)

Saturn Basics

Mass = 5.69 x 1026 kg (95 times Earth's mass) Radius= 60,500 km (9.4 times Earth's radius) Density = 710 kg/m3 (for comparison Jupiter's 1330 kg/m3)

Mars Basics:

Mass = 6.42 x 1023 kg (~11% of Earth's mass) Radius= 3395 km (~53% of Earth's radius) Density = 3930 kg/m3 (for comparison Earth is 5510 kg/m3)

Uranus Basics

Mass = 8.69 x 1025 kg (14.5 times Earth's mass; 4.6% of Jupiter's mass) Radius= 25,550 km (4 times Earth's radius, 35% of Jupiter) Density = 1290 kg/m3 (Jupiter's is 1330 kg/m3)

How is Earth's surface shaped by plate tectonics?

Measurements of plate motions confirm the idea of continental drift. Plate tectonics is responsible for subduction, seafloor spreading, mountains, rifts, and earthquakes.

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.

Look at Meteorites

Meteorites - Extraterrestrial materials that fall to earth Leftovers from solar system formation Give an indication of what elements formed the Earth

Today - Moon is "Geologically Dead"

Moon is considered geologically "dead" because geological processes have virtually stopped.

Newton's Law of Gravity: a primer

More simply: 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

Impact Cratering

Most cratering happened within 1st billion years after solar system formed. Craters are about 10 times wider than object that made them. Small craters greatly outnumber large ones.

Jupiter's Atmosphere

Mostly Hydrogen (86%) and Helium (13%) Cloud layers where ammonia (NH4) ammonium hydrosulfide (NH4SH) and water vapor (H2O) condense Belt-zone circulation (rotation period - 10h) Long-lived storms Great Red Spot visible since Galileo observed it over 400 years ago

Sources of Magnetic Fields

Motions of charged particles are what create magnetic fields. e.g. Electromagnets - magnetic fields in planets

Europa

No dark, dirty terrain - entire surface is young 100 mile deep ocean lying about 10 miles below surface Bluish-white areas - relatively uncontaminated water ice Brown areas on right - dried salts Yellowish area? cracks - up to 1800 miles long very young, bright surface

Interiors of Jovian Planets

No solid surface - just core Layers under high pressure and temperatures Cores (~10 Earth masses) made of hydrogen compounds, metals, and rock - but compressed to the size of Earth The layers are different for the different planets. WHY?

Topographic Map of Mars

Northern hemisphere - low elevations Southern hemisphere - high elevations craters- in high elevation areas of mars - no continents or ridges in low elevations like in earth

Volcanism on Mars

Olympus Mons - shield volcano - largest volcano in solar system.

2 Types of Body Seismic Waves

P-waves - push and pull - fastest waves so arrive first - Travel through solids & liquids S-waves - shake side to side or up & down - 2nd fastest, so arrive after p-waves - Travel only through solids

Types of Seismic Waves

P-waves and S-waves Body Waves - Travel through the Earth Surface Waves Travel through layers of the Earth's Surface

Erosion on Venus

Photos of rocks taken by landers show very little erosion. Too hot for water Rotation to slow for strong surface winds

Proceeding down inside Jupiter

Pressure and temperature are beyond hydrogen's critical point No clear distinction between gas and liquid states Atmosphere around you gradually increases in density until you are in a liquid A quarter of the way down hydrogen turns into liquid metallic hydrogen Electrons are ably to move freely like in a metal Rather than molten metal, this provides the source of the magnetic field

Types of Planetary Atmospheres

Primary Atmospheres: Gas collected during the formation process Example: Jovian Atmospheres mostly Hydrogen & Helium Secondary Atmospheres: Formed by outgassing during differentiation Example: Venus Tertiary Atmospheres: Secondary atmosphere that has been significantly modified Example: Earth

Jupiter's Bands

Red cloud layers are brighter in the infrared - warmer

Saturn's Colors

Saturn's layers are similar, but deeper in (and more subdued).

Shadow Zones

Seismic Waves - tells us what's inside Earth - P waves go through Earth's core, but S waves do not. - We conclude that Earth's core must have a liquid outer layer. - Size of shadow zone determines core size

Why do the Jovian planets have rings and not the terrestrial planets?

Short answer: Jovian planets have many more moons Rings formed by random impacts on the icy moons or icy moons colliding with each other

Geological Processes on Jovian Moons

Similar to those on terrestrial planets Impact cratering Volcanism Erosion from Wind & Ice So far no evidence of: Tectonics(liquid) Water Erosion

What Effects Tidal Heating

Strength of gravity - causes the tidal force Gravity depends on both mass of the moon and planet and distance between them Larger the masses - stronger the force Closer the distance - stronger the force Changing shape of orbit stretches the moon Circular orbits forces are constant and unchanging - no changing of moon shape More elliptical the orbit - more stresses from increasing/decreasing tidal forces

Types of moons orbiting the Jovian planets

Since they formed beyond the "frost line," the moons of the outer solar system have a large proportion of ice.

Sizes of Moons

Small moons (< 300 km) No geological activity Medium-sized moons (300-1500 km) Geological activity in past Large moons (> 1500 km) Ongoing geological activity

'Shepherd' Moons

Small moons can force particles into a narrow ring.

Surface of Venus

Smooth, rolling lava plains Deformed highlands (tessera) Unlike the Moon and Mercury - no ancient plains

Geological Processes on Jovian Moons

Some processes in operation on Jovian moons but not on terrestrial worlds Strong tidal forces can heat and melt the interior of the moon Liquids other than water can occur on moons that are far too cold for liquid water

Gap Moons

Some small moons create gaps within rings.

What geological evidence tells us that water once flowed on Mars?

Some surface features look like dry riverbeds. Some craters appear to be eroded. Rovers have found rocks that appear to have formed in water. Gullies in crater walls may indicate recent water flows.

Sun

Sun radiates mostly visible and IR and a small amount in UV Not all EM radiation penetrates Earth's atmosphere.

Erosion by Water

The Colorado River continues to carve Grand Canyon.

A Possible History of Mars: 3 Periods

The Noachian Period Formation- 3.5 billion years ago Thicker, warmer atmosphere - rivers, lakes, oceans Hotter interior - abundant volcanic activity, magnetic field Southern hemisphere dates from this period

Notes

The amount of energy absorbed by Earth from the Sun is equal to the amount of energy given off by Earth. If you measure the temperature of the Earth from a satellite, far above Earth's atmosphere, you would get a temperature of approximately 255 K (0oF).

Proceeding down inside Jupiter

The center of Jupiter is 5-6 times hotter than the Sun's surface - but we don'tknow much about the actual composition or structure

Tidal Heating

The moon is squished and stretched by gravity as it orbits the planet. Very elliptical orbit changes the tidal forces

Observations at other wavelengths are revealing previously invisible sights

UV Shorter lambdas Ordinary visible Map of Orion region Infrared Longer lamdas

Enceladus Medium Moons of Saturn

Tidal heating Ice fountains suggest it may have a subsurface ocean.

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Tidal stripping of ice from a titan-sized satellite

Titan - Saturn's largest moon

Titan has a thick, opaque atmosphere rich in nitrogen (98.4%), 1.6% methane and traces of other hydrocarbons (including ethane, acetylene, ethylene, and propane) - methane lakes Radar map shows few impact craters & river beds Surface mostly water ice and slushy methane

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

Volcanic Outgassing

Volcanism also releases gases from planet's interior into the atmosphere. creates secondary atmospheres

Geological Histories

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 in distant past, Random events today Can be destroyed by other geological processes

Missions to Jupiter, Saturn, Uranus & Neptune

Voyager 1 & 2: (1977-today) flybys of all Jovian planets + some moons and beyond Cassini: (NASA/ESA 1997-2017 Sept) orbiter to Saturn, lander to Titan (moon) Juno: (2011-?) orbiter to Jupiter

More info

What are Saturn's rings like?They are made up of countless individual ice particles.They are extremely thin with many gaps. How do other jovian ring systems compare to Saturn's? The other jovian planets have much fainter ring systems with smaller, darker, less numerous particles. Why do the jovian planets have rings? Ring particles are probably debris from moons.

Moon vs Mercury

What geological processes shaped our Moon? Early cratering is still present. Maria resulted from volcanism. What geological processes shaped Mercury? Had cratering and volcanism similar to Moon features indicate early shrinkage.

INFO

What is special about Titan and other major moons of the solar system? Titan is only moon with thick atmosphere. Many other major moons show signs of geological activity. Why are small icy moons more geologically active than small rocky planets? Ice melts and deforms at lower temperatures, enabling tidal heating to drive activity.

What have we learned?

What is the weather like on jovian planets? Multiple cloud layers determine colors of jovian planets .All have strong storms and winds. Do jovian planets have magnetospheres like Earth's? All have substantial magnetospheres. Jupiter's is the largest by far.

Planetary Geology

Why do all the terrestrial planets look different? What produced the surface features? Which geological processes are active on each planet and their importance?

Erosion by Wind

Wind wears away rock and builds up sand dunes. Wind can erode and deposit material - sand dunes on Mars and Earth - wind streak - Venus - erosion on Earth

Look at rocks from the Earth's Interior

Xenoliths Deepest come from ~300 km (186 miles)

Venus' Atmosphere

composition: mostly carbon dioxide pressure - 90 atm at surface water - dry (.002% at surface) Surface temperature - average 870 degrees F "Venus is the planet most like hell" - Carl Sagan

The Electromagnetic Spectrum

gamma rays: highest energy, lowest wavelength radio waves: lowest energy, highest/biggest wavelength gamma rays, x-rays, UV, visible light, infrared, microwaves, radio waves

Craters

good indication if water running - if crater then no water for a long time

Density

mass/volume Density of Matter: - how tightly packed matter is. the amount of mass in a given space solid = more dense than gas and liquid size doesn't matter but density does

View of Ring Gaps

not as solid as believed

· Source of magnetic fields

o A planet can have a magnetic field if charged particles are moving inside o Requirements: § Molten, electrically conduction interior § Moderately rapid rotation (liquid iron moving - creating current to create magnetic field) larger worlds = more gravity

· White light

o Issac newton showed: § White light could be cplit into component colors with a prism § AND THEN RECOMBINED INTO WHITE LIGHT... o Basic Properties of light § Light is radiant energy § Light travels at constant speed - 300,000 km/sec § Has characteristics of both a wave and particle o Wavelength § The colors determined by the wavelength of light - denoted by lambda § Visible light measure in: ... o ROYGBIV - visible spectrum o Red is long wavelength o Short wavelength is blue/purple o Frequency - bobbing up and down rather than a motion in the lake o Increase frequency - you increase energy o Increase wavelength - energy decrease

Tectonics

o Large-scale processes affecting the structure of the [Earth's] crust. o Plate Tectonics - Crust is fractured into plates which float on the warm underlying layer o releases heat from a hot, partially molten interior primarily at plate boundaries o Convection of the mantle creates stressed in the crust called tectonic forces o Compression of crust creates mountain ranges o Valley can form where crust is pulled apart

Uranus' & Neptune's Bands

seen in the IR

INFO

· Left to right - increasing wavelength · Right to left = increasing frequency aka increasing energy right to left · Which ray has shortest wavelength? o X-rays · Lowest energy o Radio waves

Density info

· Low density rises and high density goes to center/crust

INFO

· More greenhouse gas - more light gets trapped · More greenhouse gas - longer it takes to get back to space and longer it gets trapped · Incoming energy = outgoing energy from sun = equilibrium · Not trapping more energy on surface than we are leaking back into space ·

Venus

· More missions = more know about planet - don't need to know the missions · Similar to earth · Closest planet to earth - approaches earth closer than other planets · Hottest planet in solar system - "most like hell" (Carl Sagan) · blue = smooth rolling lava plains · white = deformed highlands - no cratering = that's why tessera because dif origin than moon · moon highlands - created by impact craters · no ancient lava plains · impact cratering - more craters = older - not case on venus · age of venus is young and cratering is uniform over surface · 500 million years of surface · compared to other planets - 500 million years is recent · many volcanos on venus · stratovolcanoes - formed by thickest lava - lets you build tall volcanos · lava plains - runniest lava - seen on moon · assume still geologically active - sulfur dioxide in atmosphere from colonic outgassing · interior of venus o volcanic features o molten interior and liquid outer core o cooling rate similar to earth o no magnetic field - 1) maybe core is solid (cools faster than earth) or 2) planet rotates very slowly (too slow to circulate charges in liquid core like earth) · erosion on venus o little erosion - no water, slow rotation rate - no wind · lander on Venus · white light - look like moon · possible history of Venus o no liquid water - cant be used to cycle out carbon dioxide - keeps carbon dioxide in atmosphere o something happened to do overturning of crust o no plate tectonics now

Cratering Rate

· estimate about age of surface

Features associated with transform boundaries

• Earthquakes

Light

• Light is radiant energy. • Speed - c = 300,000 km/sec • Has characteristics of both a wave and a particle

Features associated with divergent plate boundaries

• Mid-oceanridges • Underwater volcanism • Earthquakes

Features associated with convergent boundaries

• Mountains • Volcanism • Deepseatranches • Earthquakes