planets final

saturn moons general info

\-has many named satellites

\-one very large satellite (titan)

* only moon w/ a substantial atmosphere

\-enceladus moon

* has a liquid water ocean that we have sampled

\-many small satellites

\-has co-orbital moons (two moons on the same orbit)

titan

\-smaller diameter than earth

\-less dense than earth

\-only satellite known to have a substantial atmosphere

\-dense nitrogen and methane rich smog, obscures the surface

\-large icy mountains

\-methane ice, water ice, tar and ethane liquid lakes on majority of surface

cassini-huygens mission

* orbiter probe mission to titan
* first probe to land on a moon other than our own
* discovered info about atmosphere
* orange color is from tholins generated

tholins

* hydrocarbon particles
* do not form naturally on earth
* gives titan its orange color

titan’s atmoshpere

* titans haze is dominated by 3 smoggy layers
* produced by the action of sunlight on methane
* lower atmosphere is dominated by nitrogen, methane, and hydrogen
* no methane/ethane rain when huygens descended
* surface pressure is higher than earth’s
* titan has seasons; each season lasts 7 years
* (from bottom to top), layers order methane clouds, aerosol haze, main haze layer, ultraviolet/optical haze layer, ultraviolet-absorbing haze

surface of titan

* has a continent sized bright spot (Xanadu) and other albedo (light) differences
* darkest areas have very low albedos b/c of carbon rich surface deposits
* mountains are methane ice
* rivers are carved by liquid ethane
* only body in the solar system known to have liquid
* surface temp is very cold into the negative degrees
* too cold for most liquids and too cold for water ice in the atmosphere is nearly free of water vapor

dunes on titan

* common feature on titan
* no silicate sand available
* theorized to be a viscous dust made of some form of hydrocarbon
* thought to take a long time to form

enceladus

* smaller diameter than earth
* less dense than earth; mostly water ice
* high reflectance and no atmosphere, low surface temp
* low crater densities on some of surface
* tidal heating and some internal heat source
* volcanic eruptions of water vapor and solid water ice common at south pole
* terrain resembles ganymede
* heavily cratered polygonal areas cut by younger grooved belts and smooth plains
* smooth plains are young icy volcanic deposits
* single linear grooves in both terrains

cryovolcanism on enceladus

* ice on surface of enceladus is from globally dispersed volcanic eruptions of snow (water ice particles)
* low gravity = explosive geyser like eruptions have a wide global dispersal

lapetus

* 3rd largest moon of saturn
* smaller diameter than earth
* lower density than earth
* unique equatorial ridge
* two distinct color hemispheres
* leading hemisphere is dark w/ a slight reddish-brown coloring
* trailing hemisphere and poles are bright

mimas

* “death star” moon of saturn
* small diameter, low density
* massive impact crater

atlas and pan

* ufo moon of saturn
* have a distinct shape
* may have formed in two stages
* equatorial ridge “sweeping up” material from the rings

uranus general info

* far from sun
* 17 hr rotation
* 84 yr revolution
* large diameter
* atmosphere is hydrogen, helium, and methane
* low density
* only voyage 2 has visited this planet
* axial tilt makes it look like it has been tipped on its side

uranus axial tilt

* most likely theory: a giant impact w/ a large object may have occurred after uranus had grown to nearly full size, throwing the planet on its side
* new theory suggests uranus had a moon that slowly tipped the planet over via gravity
* moons orbit was unstable, eventually crashed into the planet

uranus seasons

* very extreme, last 21 years
* in northern hemisphere summer, it has continuous sunlight for 21 years. in the winter, it is in continual darkness

uranus atmosphere

* made of hydrogen, helium, and methane
* has faint bands of clouds that move rapidly
* only visible w/ very strong image enhancement
* there may be colored bands like jupiter’s but they are hidden from view by the methane layer
* blue in color b/c of absorption of red light by methane in the upper atmosphere
* high wind speeds
* very cold
* occasional storms
* are short lived
* produce dark and white spots in the atmosphere

uranus interior

* composed of various ices w/ rocky core
* both uranus and neptune have an inner rocky core, a slushy warm ice layer, and an outer layer of mostly molecular hydrogen

uranus magnetic field

* much stronger than earth’s
* tipped 60 degrees from the rotational axis (earth’s is about 12 degrees off the rotational axis)
* the magnetic axis does not pass through the planet’s center
* field is not a single dipole
* no simple north-south dipole, there are more directions as well
* conductive mix of water, methane, and amonia in layers

uranus ring system structure

* composed of fairly large icy particles
* 11 known rings
* all very faint
* brightest is the epsilon ring
* the rings lie in a sub-vertical plane of the equator

uranus ring system discovery

* nine of the eleven rings of uranus were discovered in 1977 from earth
* by watching the occultation of a star as each ring passes in front of it
* occultation is the passage of one body in front of another, temporarily blocking its light

uranus ring system composition

* particles are very dark
* composed of frozen methane rich mix of ices and dust
* break down of the methane by radiation leaves a dark carbon film on the surface of each particle
* 2 shepherd moons
* contribute to the shape of epsilon ring
* epsilon ring:
* voyager imaged the multi-ring nature
* each sub-ring is less than 1 km across

uranus moons

* three classes of moons:
* small very dark inner ones discovered by voyager 2
* larger ones
* newly discovered much more distant small moons
* most have nearly circular orbits in the plane of uranus’ equator
* \

miranda uranus moon

* 11th of uranus’ known satellites
* the innermost of uranus’ large moons
* half water ice half rocky material
* weird surface features
* suffered intense geologic activity
* wide age range
* surface is heavily cratered terrain w/ grooves, valleys, and cliffs
* verona rupes cliff

titania uranus moon

* largest of uranus’ satellites
* surface is cratered terrain and very long interconnected valleys
* may be volcanism
* mix of water, methane ice, and silicate rock
* messina chasma
* comparable to valles marineris on mars
* 5 km deep and over 1448 km long

\

oberon uranus moon

* second largest uranus moon
* furthest away of the large moons
* tidally locked
* made of rock and ice
* two types of surface features
* craters
* chasmata
* canyons cratered by extension
* icy surface cracked forming these canyons

ariel uranus moon

* water ice and rock
* young craters
* icy volcanism

umbriel uranus moon

* water ice and rock
* heavily cratered and dark surface

neptune general info

* far from sun
* 15 hr rotation
* 164 yr revolution
* large diameter
* slight axial tilt
* similar to earths, giving it seasons
* hydrogen, helium, and methane atmosphere
* low density
* one day takes about 16 hrs
* spinning so fasts, creates oblate shape
* predicted to exist b/c Uranus was a known planet and it’s orbit was off, so there had to be another planet out there affecting it.

neptune atmosphere

* blue color (like uranus) is produced by methane gas
* absorbs the red light from the sun
* warmer than uranus
* source of the internal heat source is unknown

neptune great dark spot

* about the size of earth
* rotates around neptune once every 16 days
* created by convecting gas rising from the interior
* similiar to jupiter great red spot

neptune clouds

* neptunes winds are very fast
* voyager capture white wispy methane-ice clouds

neptune interior

* very similar to Uranus
* but slightly greater proportion of rock
* hydrogen-rich atmosphere gives way internally to mantle layer of water, methane and ammonia ices/slush
* overlies a rocky core

neptune diamond rain

* diamond is a carbon based mineral
* requires extremely high pressure and temp to get carbon to arrange in this structure
* large amount of carbon locked up in neptune produces diamonds
* pressure under atmosphere is high enough to generate diamonds
* and internal heat
* diamonds are created as methane breaks down
* carbon forms diamonds that fall through ice layer and are deposited

neptune magnetic field

* strange magnetic field like Uranus
* less than half as strong as earths magnetic field
* \

neptune ring system

* rings are very dark like uranus and jupiter
* probably ice and dust mixture
* two known shepherd moons
* one ring appears twisted

neptune moons

* all likely to be captured kuiper belt objects

proteus neptune moon

* second largest neptune moon
* irregular shape
* heavily cratered surface, no signs of geologic activity

larissa neptune moon

* found near the ring system
* irregular shape
* heavily cratered surface, no signs of geologic activity
* very circular, unstable orbit

triton neptune moon

* largest neptune moon
* retrograde orbit around neptune
* must have formed outside of neptune’s orbit and was captured by it
* varied surface w/ active ice volcanoes
* low crater density, very few craters
* polar caps
* ridge networks
* pitted surface called cantaloupe terrain
* very cold atmosphere
* entire southern hemisphere is covered with an ice cap of frozen nitrogen and methane

neptune moon triton ice volcanoes

* eruptive material - liquid nitrogen
* quickly turns to ice
* eruptions are driven by seasonal heating from sun

kuiper belt

* lies beyond neptune
* objects such as pluto, charon, and others
* discovered in ‘92
* potential source of short-period comets
* dynamically active region created by outward motion of neptune billions of years ago
* exact origin remains unknown
* formation of jupiter/saturn may have forced this material out from inner solar system, then neptunes creation pushed it further out

trans neptunian objects

* any minor or dwarf planet that orbits the sun at a greater average distance than neptune
* includes kuiper belt, of which pluto is one of the largest planets

pluto general info

* 6 day rotation
* 247 yr revolution
* tilted on axis
* no atmosphere
* low density
* diameter is smaller than our moon
* way less dense than other rocky planets
* mostly composed of ices
* weird elliptical orbit
* sometimes closer to sun than neptune
* plane of equator is almost a right angle to plane of its orbit (like uranus)

pluto atmosphere

* little to no atmosphere
* haze layer of gases exists when sunlight sublimates ices on surface
* most gases locked in surface
* tholins may be present to create red color

pluto interior

* divided into 3 layers
* no magnetic field detected
* core must be solid
* may have a liquid water ocean under ice

pluto surface

* nitrogen, methane, and carbon dioxide ices
* wide age range of features
* lots of craters
* smooth icy plains

pluto tombaugh regio

* “heart” region
* two distinct lobes
* smooth western lobe - sputnik planitia (still geologically active)
* eastern lobe - mountainous terrain
* mountains made of nitrogen, methane, carbon monoxide

__cycling of nitrogen across region__

* nitrogen sublimates and is transported away - deposited elsewhere
* ice falls on eastern lobe builds mountains and glaciers
* glaciers transport ice to sputnik planitia
* transverse dunes also found in western portion

pluto macula

* spaced out dark regions intersected by topographic highs
* canyons run through dark regions, measure several km’s deep
* largest is Cthulhu macula
* has hundreds of craters, must be older than tombaugh regio
* dark colors assumed to be complex mix of tholins that formed ices

pluto montes

* ice mountains found on pluto surface
* highest - tenzing montes
* very steep mountains
* must be made of water ice

pluto moons

* 5 known moons
* largest - charon
* more complex than the other moons
* small moons assumed to be impact ejecta

charon pluto moon

* tidally locked
* same side always faces pluto
* hovers over the sam location on pluto’s surface
* exerts large influence on pluto

surface features

* has red regions similar to pluto caused by tholins
* surface is much more dominated by water ice
* chasma
* canyon systems; serenity chasma is the largest
* mons
* most bizarre - kubrick mons, sits in a moat
* thought to be a cryovolcano

arrokoth

* two lobes attached by a narrow neck
* red coloration caused by tholins
* implies that methane and ammonia may be present
* formation - possibly two objects stuck together at low velocity. evidence for low energy formation rather than a big impact

eris

* dwarf planet, comparable in size to pluto
* one known moon - dysnomia
* methane and water ices present

comets general info

* icy bodies originated in outer solar system
* oort cloud
* some from kuiper belt
* if get close to sun, begin to sublimate and produce material for comet’s tail
* loose mass every close orbit to the sun
* cross all the planetary orbits

comet origins

* have small masses
* orbits easily disrupted
* scattered into variety of orbits during solar system formation
* large orbits make up the oort cloud
* smaller orbits make up kuiper belt
* very large orbits; may escape sun altogether

comet orbits

* most comets take hundreds, thousands, and millions of years to orbit sun
* some w/ orbital periods less than 200 yrs known as short-period comets
* all highly eccentric orbits and at all inclinations to ecliptic
* makes them very dangerous for potential to impact a planet

comet structure

* cometary nucleus
* ice and gas w/ some dust
* as nucleus sublimates, comet forms a weakly held atmosphere called the __coma__
* made up of water, carbon dioxide, and other gases
* near sun, coma can expand to 100,000 km & tails can be millions of km long

comet tails

* sunlight and solar wind produce two tails
* ion or gas tail
* ions swept directly away from sun by solar wind
* straight and narrow
* dust tail
* solid denser particles driven off coma
* wide and diffuse
* usually curved (start to orbit sun)
* eventually these particules orbit sun
* point away from sun

Halley’s comet

* best known short-period comet
* visible from earth
* might appear twice in a human lifespan
* very dark
* one of the darkest objects in solar system
* carbon rich
* low density
* porous

comet exploration rosetta spacecraft

* also contained the Philae lander
* became first lander on nucleus of a comet
* landing mechanism failed - probe bounced around until resting on surface
* eventually failed; stuck in a crevasse
* surface of 67p made up of various defined terrains
* organic molecules were identified
* composition of water vapor very dif to earth

asteroids

* small airless, rocky bodies that orbit sun
* much smaller than planets
* remnants left over from the formation of solar system
* most found in asteroid belt
* between mars and jupiter
* can have moons
* some have large diameter
* largest is ceres
* next largest: pallas, vesta, hygiea

main characteristics

* low eccentricities
* never perfect circles
* variable albedos
* highly cratered old surfaces
* asymmetric shapes
* metallic and stormy

asteroid belt

* between mars and jupiter
* most known asteroids found here
* some have irregular orbits
* divided into subgroups
* named after main asteroid in group
* classified based on their spectra (chemical comp) and albedo

types of asteroids

* c-type
* includes more than 75% known asteroids
* very dark & carbon rich
* s-type
* 17%
* relatively bright
* metallic nickel-iron mixed w/ iron and magnesium silicates
* m-type
* bright
* pure nickel iron

asteroid origins

* planetesimals (small planet-like bodies) that never grew into a planet due to proximity to jupiter
* composition differences and lack of differences suggest some were never single planets that broke apart
* gaps are found between main concentrations of asteroids in main belt
* empty regions - kirkwood gaps

near earth asteroids

* NEA’s
* closely approach or cross earth’s orbit
* mass extinction events on earth linked to asteroid impacts

eros asteroid

* s-type asteroid
* highly cratered old surface
* second largest near earth asteroid
* about same density as earth’s crust
* 5 hr rotation

ceres asteroid

* largest object in asteroid belt
* largest dwarf planet in neptune’s orbit
* only object in asteroid belt that has been rounded by its own gravity
* one of few asteroids to have been differentiated
* heavy elements sank to core, lighter elements form the mantle/crust
* surface is a mix of water ice, hydrated minerals, and basaltic lava flows
* possible cryovolcanism
* tholins
* bright spots

meteorites

* fragments from asteroid belt
* some fragments of planet/satellite surfaces
* exceed the escape velocities following impacts
* could find samples from moon, mars, mercury
* dif types of meteorites assigned to dif asteroid sources
* iron meteorites - M-type asteroids
* stony-irons - S-type asteroids

meteoroids

* rocky/metallic bodies w/ earth-crossing orbits
* meteors (shooting stars)
* meteoroids glow as they heat up through earth’s atmosphere
* meteorite: meteoroid found on earth’s surface
* smallest meteorids are dust particles
* most meteorites recovered from hot and cold desert regions on earth

meteorite classifications

* irons
* stony irons
* stones

shooting stars

* meteoroid surfaces starts to melt on entry to atmosphere
* this is why they glow
* find dark crust, melt pits, streaks of melt and aerodynamic molding

stars

* have lifecycles
* therefore, various dif types
* can be divided into low and high mass
* amount of material to create a star depends on conditions in stellar nursery

lifecycle of sun

* massive cloud of gas and dust that permits the formation of new stars
* formation of larger mass stars can prohibit development of more low mass stars

classification of stars

* classify stars based on looks
* done by looking at colors
* blue stars: hotter
* red stars: colder
* dif letters for dif stars
* allows comparison of stars w/ similar temps but dif luminosities

absolute magnitude of star

how bright the star would be if it was 10 parsecs from earth

sun general info

* classified as a G2 V star
* middle-aged star
* big diameter
* 10x bigger than Jup
* large mass
* density of sun similar to Jup

plasma

* gas in the sun is super heated
* ceases to be a gas and is called plasma
* plasma is sometimes called the 4th state of matter
* in a solid, liquid, or gas, an atom has protons, neutrons, and electrons
* in a plasma, electrons can move freely
* flow of plasma outwards from the sun is solar wind

sun rotation

* counterclockwise
* differential rotation (like Jup and saturn)
* \~25 days at equator
* \~36 days at poles
* axial tilt:
* sun’s axis inclined 7 degrees from the ecliptic

sun interior

* with increasing depth, the sun increases in pressure, density, and temp
* all energy of the sun is created in the core; flows outward
* occurs by 3 mechanisms:
* conduction (only in core)
* radiation
* convection

sun core

* very high density
* 10x denser than lead
* hot

sun radiation zone

* radiative heat transfer
* composed of ionized gases, mostly hydrogen
* convection zone
* zone of active circulation of gases and convection heat transfer
* up to the sun’s surface
* the outer shell of the sun that we see from earth is the top of the turbulent convection zone known as the photosphere

sun granulation

* photosphere/convection zone surface mottled by a pattern of bright cells called granulation
* surface expression of underlying convection cells (“hot bubbles”)

photosphere

visible yellow surface on sun

\~500 km deep, 5500 K surface temp

sunspot

* dark spots on the photosphere that contain intense magnetic fields
* dark b/c they are cooler than surrounding photosphere
* tend to form in groups
* last 2 months or more; most last 1 week
* divided into two regions
* umbra
* darkest region
* magnetic field is vertically aligned to the sun’s surface
* penumbra
* magnetic field sits at a variable incline to the umbra
* **influence climate on earth (less spots = cooler earth)**
* have been steadily declining

chromosphere

* thick layer of thin gas on sun
* fainter than photosphere
* only visible during solar eclipse
* high temps
* \

sun corona

* outermost part of atmosphere
* composed of very low-density ionized gases
* glow only visible during total eclipses or w/ a special telescope

solar wind

* rapidly moving outward extension of the corona
* remnant of proto-stellar jets
* composed mostly of ionized gases
* hydrogens and protons w/ free electrons = plasma
* “gusts” of solar wind
* associated w/ solar flares
* cause magnetic disturbances on earth

prominences

* protrusions of ionized gases, mostly hydrogen, from the chromosphere
* commonly looper, controlled by magnetic fields
* gas travels along twisted magnetic fields emanating from areas around sunspots

solar flares

* chromosphere eruption (not looped) of ionized gases, x-rays, and UV/visible light
* rises rapidly in a few minutes then decays over an hour or less
* significant effects on earth
* most flares become “gusts” in the solar wind and reach earth after a few hours/days
* can create a magnetic storm on earth that affects communications and increased auroral activity near the poles

coronal mass ejections

* significant release of plasma
* often follow solar flares
* associated w/ large changes in the magnetic field
* unlike solar flares this is a directed blast of plasma
* also travels at much slower speeds than solar flares do

geomagnetic storms

* combination of solar flares and coronal mass ejections
* can be very hazardous
* can cause blackouts on power grid
* disrupt transmission of radio waves
* degrade radios and GPSs

planetary system formation

* all formed from a spinning disk
* known as solar nebula
* rotations due to original rotation of the original disk
* plus disruptions due to impacts
* many asteroids are planetismals that never formed larger planets
* therefore meteorites can be used to understand the formation of rocky planets

stony meteorite classification

* chondrites and achondrites
* chondrites: contain structures called chondrules
* rounded droplets of melted rock

planetary system formation theory considerations

* composition
* size
* position relative to star of all extrasolar planets

giant molecular clouds

* “star factories”
* numerous regions of gas and dust dispersed among our galaxy
* largest are known as giant molecular clouds
* closest GMC is in the orion nebula
* numerous proplyds have been observed
* most of gas is hydrogen and helium w/ very minor amounts of other elements
* most of the molecules are bound in very small rocky-icy grains or as a gas

orion nebula

* millions of new stars are forming in this cloud now
* many display proplyds
* orion nebula star cluster is less than 1 mil yrs old
* planets are likely to still be forming
* star formation happens in the densest and hottest parts of these clouds
* this is b/c the dense areas have the most material that is able to form stars
* stars form in clusters off thousands to millions
* proplyds and planets form around stars surrounding dust (silicate), ice, and gas

star formation

* molecules in densest clumps in the GMC begin to collide w/ increasing velocity
* clumps attracts more matter by gravity
* gas collapses locally to form a “stellar accretion disk”

stages of star formation that initiate nuclear fusion

* motion of collapse and collision is converted to heat
* temps rise to millions of degrees
* pressure builds to billions in atmospheres
* these conditions initiate fusion of hydrogen to form helium
* release of electromagnetic energy
* this energy release creates outward pressure
* until an equilibrium between gravity and thus pressure is reached
* a stable star is formed
* outwards pressure may initiate new star formation in the GMC

proto-planetary disks (proplyd)

* contraction of any spinning material or body (in this case by gravity) causes it to spin faster and __get hotter__
* if the spin rate is hot enough,
* gas and dust forced out
* thrown into orbit around star
* different material migrates in the protoplanetary disk
* high melting point materials condense in inner disk and low melting point materials in outer nebula
* silicates/metal → inner
* ices/gases → outer
* stellar jets also force low density material towards edge of disk
* stars older than a few million years
* no proplyds
* planets must form “rapidly” following proto-star formation
* gas giants probably form quicker than terrestrial planets
* have lots of hydrogen and helium from solar nebula

stellar jets

* after few hundred thousand years charged particles from stars erode proplyd from inside out
* solar wind is a remnant of these jets
* spectacular jets (protostellar jets) are formed at the poles of the newly formed star
* effects of stellar jets for formation of planets
* gas giants formed at this time
* before most of gas disk was blown away
* most of low density and low melting point materials are forced to edge of disk by these jets
* condense to form mostly ice
* comets, kuiper belt, oort clouds
* young proto-stars are associated w/ bipolar jets
* erode the surrounding (proplyd) disk
* flaring of the proplyd
* the solar nebula is most likely flared at its edges