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Midterm 2
Solar System Formation & Planets
65
Astronomy
Undergraduate 1
03/05/2008

Additional Astronomy Flashcards

 


 

Cards

Term
Nebular Hypothesis
Definition
  • Molecular Cloud Collapsed
  • Cloud fragments into smaller, denser pockets of matter
  • In center, gravity brings material together to form star -- Sun
  • Conservation of Angular Momentum -- the spinning of everything in Solar System
Term
Close Encounter Hypothesis
Definition
  • Blobs of gas that were ripped from the Sun during a near-collsion with another star
  • Flaming matter from each star could eventually form planets (?)
  • BUT Colliding stars are very rare! They're very far apart (galaxies are relatively close together, hense other theory more likely)
Term
Big Bang
Definition
  • 13.7 Billion years ago
  • Supplied Universe with H, He
    • only small fraction of original H, He has been converted into heavier elements
  • First stars used H, He in nuclear reactors
  • Materials recycled into new generations of stars
Term
Solar System Composition
Definition
  • 98% H, He
  • 2% everything else (metals)
    • more than enough to form all of the terrestrial planets and astroids 
  • The Sun is very metalic compared to other stars the same age
Term
Molecular Cloud
Definition
  • A Vast cloud of cold gas and dust that contains the raw material of stars and planets, mostly H, He
  • No real shape
Term
Collapsing Molecular Clouds
Definition
A collision with another cloud or a shock wave from an exploding star may cause the cloud to start collapsing
Term
Planetary Birth
Definition
  • We see stars being born all the time from nebula!
  • radiation burns away cloud, leaving only stars
  • Stars with dust disks -- dust disk form planets
Term
Planetary Accretion
Definition
  • CONDENSATION: the general process in which solid particles condense out of a gaseous nebula
    • H, He -- never condense b/c so light
    • H compounds -- methane, amonia, water --> ice
    • Rock -- solid particles at low temps but gaseous at high temps
    • Metals -- solid particles at low temps but gaseous at high temps. Only found in certain regions based on star temp
Term
Zone of Inner Planets
Definition
Area dominated by rock and meta, which clumped together into ever-larger bodies, called planetesimals, eventually forming Mercury, Venus, Earth and Mars.
Term
Planetesimals
Definition
Small grains of dust aggregated together that grow by collisional aggregations. The collisions and heat will cause them to get bigger.
Term
Zone of the Outer Planets
Definition
Area dominated by ices and light elements, which also condensed to form the gas giant planet cores. 
 
Lighter elements were blown out by solar wind. 
Term
The Solar Wind
Definition
Young stars have strong winds that clear our light gases (H, He)
 
It's the inside of the gas ball trying to get out 
 
GOOD for us--if left behind, H and He would have condensed on all of the planets 
Term
Moon Formation
Definition
  • Some formed at same time as planet
    • orbit in equitorial plane 
  • Some captured objects
    • do NOT orbit in equitorial plane 
  • Gas Giants all had mini nebula around them that collapsed, thats how you can tell some moons formed with planet bc they orbit and rotate in same direction
Term

Earth's Moon Formation

Close Encounter Hypothesis 

Definition
Probably formed AFTER Earth did, when a body several times as massive as Mars slammed into it
Term
Asteroids
Definition
Rocky peices that never formed a planet because the gravity of nearby Jupiter kept pulling them apart 
 
(Jupiter also keeps them from hitting inner planets) 
Term
How old is our Solar System?
Definition
  • Radioactive Decay
    • what's left tells us how much was there at the start 
  • Meteorites & Earth Rocks
    • Geological dating 
  • 4.6 BILLION YEARS OLD!

Term
Extrasolar Planets
Definition
  • Discovery: Periodic Doppler Shift in spectrum
  • Most are closer to their stars and more massive than our SS with much faster revolution
    • different stage of SS life?
    • smaller planets may have been ejected 
  • Eart-like planet discovered!
Term

Terrestrial Planets

(Basics) 

Definition
  • Mercury, Venus, Earth, Mars
  • Thin atmospheres
  • only just large enough to be shaped into spheres
  • Rocky/Metalic
Term
Accretion
Definition
Coming together--impacts from asterpoids, comets, and other debris
Term
Differentiation
Definition
Heavy material sinks, light material rises in platenary interiors
Term

Radioactive Decay

(Planetary Interiors) 

Definition
radioactive materials release heat, keep core molten
Term
Terrestrial Planetary Interiors
Definition
  • Heat inside causes earthquakes and volcanism
  • Planets continue to cool down
    • rate of cooling depends on:
      • initial amount of radioactive material
      • whether of not there's an atmosphere
      • distance from warming object (sun)
  • Interior determines in planet is "alive" (geological activity)
  • Three Layers:
    • CORE: highest density material (nickel, iron)
    • MANTLE: rocky material (minerals with silicon, oxygen)
    • CRUST: lowst density material (granite, basalt) 
  • Differentiation!!!
Term
Differences in Small vs. Large Terrestrial Planets
Definition
  • Small
    • cold interiors, little to no atmosphere (heat escapes), cooled quickly and gases escaped b/c of lack of graviational pull
  • Large
    • warmer interiors, atmospheres, geological activity
Term
Distance of Terrestrial Planets
Definition
  • "Just Right"
  • Close to sun = warm surfaces, no atmospheres, no water (b/c solar wind too strong)
  • Intermediate = moderate temps, water
  • Far from sun = cool surfaces, ice, snow, less erosion
Term
Terrestrial Weather
Definition
  • SLOW ROTATION = less wind, weather & erosion
  • MODERATE ROTATION (~24 hr) = more wind, weather & erosion
Term
MERCURY
Definition
  • Smallest Planet
  • Closest Planet
  • Large Iron Core (perhaps Mercury was once larger)
  • NO plate tectonics or volcanism for past 4 billion years
  • Rotation Rate: 3 times for every 2 orbits -- Synchronous Rotation -- day is almost as long as year! (tidally locked system)
  •  Orbitb: 88 days
  • Heavily Cratered Surface, volcanic outflow before
  • Scarps: uplifted crust
Term
VENUS
Definition
  • Earth's "Twin"
  • Always completely covered in clouds
  • THICK atmosphere
  • Hottest surface temp (greenhouse effect)
  • 90x surface pressure of Earth
  • Slowest rotation rate: 243 days
  • Spins backward (retrograde) E to W: perhaps struck by impactor?
  • Mapped by Magellan 1989
  • Geologic Activity: may still be active
Term
EARTH
Definition
  • Hot interior, geologically active
  • erosion erased craters
  • rapid spin and molten interior = magnetic field
    • changes over time
    • sometimes reversed
    • most solar wind deflected by magnetosphere 
Term
Aurorae
Definition
Caused by energetic electrons and protons moving along the magnetic field and striking air molecules, causing them to glow
 
Most commonly view at poles b/c magnetic field weaker 
Term
The Moon
Definition
  • 1/4 size of Earth (large for a moon)
  • 1/6 the gravity of Earth
  • heavily impacted
  • no atmosphere
  • Water detected on poles
  • Highlands: light colors, rough craters, old
  • Maria: dark colors, smooth, young, lava flows
    • large object cut thru crust to let lava out b/c crust thinner there (graviational pull shifted core)
  • Farside: mostly highland, no maria
  • Differentiated
  • Regolith: fine powder from all the impacts (looks brown talcum powder, but colorful under microscope)
Term
MARS
Definition
  • Half Earth's size
  • No geological activity
  • Slight magnetic field
  • Olympus Mons: largest volcano in solar system
  • Tharsis Region: 3 large volcanos spanning 1/2 size of US
  • Valles Marineris: 7x deeper than Grand Canyon, formed by crustal streching
  • Evidence of water in past
    • Schiaparelli: "canali"=channels
    • Lowell: "canali"=canals
    • Polar ice caps change with seasons
    • Frost
    • Used to have bigger atmosphere to allow water to exist--but interior cooled, gases escaped and surface cooled, water now under surface, how much?
  • Thin CO2 atmosphere
  • 2 moons
    • Phobos: captured asteroid
    • Deimos: captured asteroid (ice and rock)
  • Metorites look different
  • Use Antarctica to study Mars: Antarctic Dry Valleys
  • Only 1/3 Mars missions successful
Term

Geological Processes

Terrestrial Planets 

Definition
  • Cratering
  • Tectonics
  • Volcanism
  • Erosion
Term
Atmospheres: Terrestrial Planets
Definition
  • Layer of Gas that surrounds a world
  • Doesn't "end" just fades away
  • Makes surfaces warmer (greenhouse effect)
  • Absorb and scatter light
  • Create pressure to allow water to form
  • Create wind and weather, erosion
  • Create Magnetosphere to protect from losing gas
Term
Atmospheric Pressure
Definition
  • P = F/A = ma/A = mg/A
  • E~T
  • Collision of atoms and molecules creates pressure in atmosphere
  • Heating causes atoms to collide more (cooling collide less)
  • Pressure decreases as altitude increase
Term
Earth's Atmosphere
Definition
  • 78% N, 21% O, 0.9% Ar, 0.1% Other (CO2)
  • Early atmosphere: outgassing
  • Molecules broken down by sunlight
  • Some gasses escape b/c of weak gravity
  • Plants provide most Oxygen
Term
Venus's Atmosphere
Definition
  • Thick CO2 (95%)
  • Clouds made of Sulfuric Acid
  • Sulfuric Acid rain
  • Weather patterns seen in clouds
  • NO water vapor
  • Radiation bounced around by Carbon Dioxide
  • Runaway Greenhouse Effect: high surface temp and pressure
Term
Mercury's Atmosphere
Definition
  • Almost no atmosphere
  • H, He from Solar wind temporarily trapped
  • Atoms quickly escape to space, therefore constantly replenished
  • Extreme temp changes
Term
Mars' Atmosphere
Definition
  • Very thin, Carnon Dioxide
  • Changes in size w/ season
  • Polar caps change in size accordingly as CO2 is sublimated into atmospheric gas (summer) and condensed in solid (winter)
  • HST, Viking to Mars
Term
Long Term Climate Change
Definition
  • Climate change is common
  • Snowball Earth
  • Ice ages
  • Warm periods
  • FOUR FACTORS:
    • Solar Brightening (sun gets brighter over time)
    • Changes in axis tilt (pressesion)
    • Changes in planet's reflectivity (albedo can warm or cool planet)
    • Changes in amount of Greenhouse Gases (allow more or less radiation to surface)
Term
Gain/Loss of Gasses in Atmosphere
Definition
GAIN
  • Outgassing from interior
  • Evaporation of water and ice from surface
  • Meteroitic bombardment onto rocks
LOSS
  • Condensation
  • Chemical Reactions
  • Solar Wind Stripping high in atmosphere
  • Thermal escape when gas reaches escape veolocity
  • Meteroitic bombardment onto rocks
Term
Jovian Planet Basics
Definition
  • Solar wind blew gases to outer solar system
  • Rocky material formed rings around the planets at same time the planets formed
  • Mostly H and H compounds
  • BIG atmospheres
  • NO crust
  • Small liquid metal cores (magnetic fields)
  • Less dense (D=M/v)
Term
Jupiter
Definition
  • 1400x Earth's size--Largest Planet!
  • Strong Graviational field -- attracts asteroids and comets, keeps from hitting Earth
  • 63 moons
  • Rotation: 10 hour
  • White zones of rising air: amonia clouds
  • Dark belts of falling air: no amonia
  • Atmosphere mostly water and amonia
    • Each layer has unique color and chemistry
      • white: amonia cloud
      •  yellow, red, brown: amonia ice
      • blue: water ice
  •  Great Red Spot: hurricane with CC circulating winds (high pressure)
  • Four largest moons: Gallilean Satelites
    • Formed when Jupiter formed
  • Icy/slushie moons, tidal heating (volcanism and tectonics b/c of gravitational forces oflarge planets)
  • RINGS: Most likely created by debris from impact events on the moons. Dark material, no ice
Term
Io
Definition
  • Moon of Jupiter
  • Most volcanically active object in our Solar System
  • Gravitational tug from Jupiter make an active interior
  • Young surface
  • Sulfur emissions (100s of km)
Term
Europa
Definition
  • Moon of Jupiter
  • Rocky composition
  • Evidence for salty liquid ocean under ice
  • Oxygen ?
  • Energetic interior
  • Nutrients from inner may allow life
  • Active moon with a young surface
  • Evidence in ice for shifting, rifting, and ice bergs
Term
Ganymede
Definition
  • Largest moon in the Solar System
  • Water ice surface
  • Possible 150-km deep ocean
  • Water from below “slushed” up to the surface
Term
Callisto
Definition
  • Heavily cratered ice ball
  • NO volcanic or tectonic features
  • No heat
  • NOT differentiated
  • Rock and Ice evenly mixed in interior
Term
Saturn
Definition
  • Gallileo confused by hotdog shape
    •  higher resolution telescope showed rings in 1659
  •  75% H, 25% He
  • Traces on water, methane, amonia, rock
  • No solid surface
  • 60 moons
  • Rotation: 11hrs
  • Clouds lie deeper in atmosphere
  • Cold atmosphere
    • layers thicker bc gravity less 
  • RINGS!
Term
Rings
Definition
  • Very THIN
    • 250,000km diameter, only 10s m thick
  • Water ice, rocky particles with ice coatings
  • Wide gaps: particles accreted onto nearby moons
    • Sheparding Moons
      • Prometheus
      • Pandora
    • Moons supply particles 
Term
Titan
Definition
  • Moon of Saturn
  • Observed by Huygens
  • 1/2 water/ice, 1/2 rock, earthlike?
  • Interior may still be hot
  • Surrounded by thick N atmosphere
  • Trace amounts of organic compouds (early Earth)
  • HST -- show light and dark areas, pools?
  • Cassini/Huygens Mission (launched 1997)
    • found ice and tar, clashing ridges (Titanquakes), few craters (resurfacing)
  • Methane lakes
  • COLD
  • Methane rain
  • Evaporation of methane
Term
Mimas
Definition
  • Moon of Saturn
  • 392 km in diameter
    Large crater is ~1/3 that
    size (140 km)!
  • Looks like eye ball!
  • Why didn't it break up? HARD material?
Term
Enceladus
Definition
  • Moon of Saturn
  • Reflects most sunlight (95%)
  • Icy particles errupt
  • Tides?
  • Radioactive heating?
Term
Hyperion
Definition
  • Moon of Saturn
  • ~280 km across
  • Most-impacted object
  • Dark material composition
  • >1.5 million km from Saturn
Term
Uranus
Definition
  • Found by Hershel (1781)
  • Tilted on side 90% so one hemisphere always faces Sun
  • 27 moons
  • 11 rings
  • First object observed w/ telescope
  • Moons and rings are
    tilted, too
  • Uranus rotates backwards!
  • Rotation: 17hrs
  • Orbits in 84years
  • Tilts = extreme seasons, poles see darkness for 42 years at a time
  • Thick clouds
  • Methane gas and snowflakes
  • Atmosphere absorbs red light, blue light reflected
  • Sufferes smog that sunlight cannot penetrate
Term
Bode's Law
Definition
  • There was irregularily in Uranus' orbit, thought there must be another gravitational body out there
  •  Used this law to predict distance from the Sun
  •  Nearly accurate for all known planets, so they started searching for what would be Neptune
Term
Neptune
Definition
  • First planet to be
    predicted to exist
    by Adams (1843)
    and Le Verrier (1846)
  • Rotation: 16hrs
  • Mostly made of methane gas, methane “snowflakes”
  • Deeper blue because more sunlight reaches down to the clouds
  • Neptune has also had a giant storm in its clouds
    • Voyager, Hubble 
  • Rings:
    • Particles should be uniformly distributed,
      but are confined instead by Galatea (sheparding moon)
Term
Triton
Definition
  • Orbits backwards (retrograde) and at an inclination
  • Probably a captured Kuiper Belt Object
  • Coldest object in the Solar System - it
    reflects all of the light that reaches it
  • Icy volcanism
  • Tectonic ridges
  • Thin atmosphere
  • Surface undisturbed for long time
Term
Asteroids
Definition
  • Most lie in asteroid belt b/w Mars and Jupiter
  • Trojan asteroids: clump near Jupiter
  • Chunks of rock left over after SS formation Gravity kept them from forming a planet
  • Hard to see
  • First discovered 1800s
  • Ceres ~1000km -- largest
  • NEA pass thruinner solar system
  • Some may be extinct comet nuclei
  • Orbit in same direction as planet
  • Inclinded to ecliptic plane 20-30°
  • Ave. distance b/w asteroids millions of miles BUT collisions do occur
  • Carbon rich materials, dark rocky materials, Fe, Ni
Term
Orbital Ressonances
Definition
  • Gravity tugs at certain locations in the Asteroid
    Belt and creates gaps
  • Whenever certain objects line up, gravity pushes
    asteroids out of orbit
Term
Meteorites
Definition
  • Chunks of asteroids that have fallen to Earth
  • As they're falling -- "Meteors"
  • Carbon, Iron, Nickle
  • Show evidence that some asteroids were large enough to differentiate, have volcanism and contain water!
  • 20,000 collected so far
Term
Comets
Definition
  • Nucleus: dirty snowball
    • Rock dust and ices are abundant
  • Coma: luminous sphere of gases around nucleus when heated by the sune
  • Tail: fat moving ions affected by solar wind, slow moving dust affected by radiation pressure
    • Dust tail: follows path
    • Ion tail: points away from sun
  • Meteor Showers: pieces of comet tail
  • What do they tell us?
    • dust and gas composition tell about SS formation/composition
    • don't interact with much so they are unchanged so they are more like the original 
  • 50-50,000 AU away
  • Scattered from interations w/ gas giants
Term
Short Period Comets
Definition
  • Kuiper Belt
  • 30-50 AU
  • Gravitational effects from Neptune keep the
    objects in orbit or perturb them to fall out
  • Periods less than 200 years
  • Orbit in same plane as planets and moons (ecliptic)
  • Move in same direction around Sun as planets
  • Comet Halley
    • 1910, 1987
    • Water, ammonia, cyanide, formaldehyde 
Term
Long Period Comets
Definition
  • Oort Cloud
  • 100-50,000+ AU
  • Gravitational effects from near-by stars, galaxies
  • 200 - 50,000+ year periods
  • Half are Earth crossers
  • Comet Hykutake (72,000yr)
    • Evidence for ethane, methane
      → not seen in other comets
  • Comet Hale-Bop (2400yr)
  • LARGE
Term
Comet Missions
Definition
  • Galileo fly by (1989)
  • Deep Space 1 fly by (2001)
  • Stardust (currently collecting data) --gel stuff
  • Rosetta (launched, arrival in 2014)
  • Deep Impact (December 2004 launch)
Term
Sun Grazers
Definition
Comets affected by gravitational pull from Sun
Term
Pluto
Definition
  • Discovered by Claude Tombaugh (American)
    in 1930
  • Though to exist since motions of Uranus and Neptune seemed affected by “something”
  • Found as moving “dot” on photographic plates
  • Composition is 70% rock and 30% water (?)
  • Small atmosphere that changes in size due to distance from the Sun
  • Composed of N?
  • ~6.4 day retrograde rotation period
  • Takes 248 years to orbit Sun once
  • Moons: Charon (2 others)
    • rotate around eachother
    • Double planet system?
  • New Horizons Mission
  • Does NOT orbit in plane of ecliptic (17°)
  • Pluto's orbit goes in Kuiper belt -- KBO
  • Object found LARGER than Pluto
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