Post on 16-Aug-2020
ABOUT THE MIDTERM
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
About the Midterm
• Same “rules”
• Use your index card!
• About the same length/structure
• Objects in the Solar System through Stars & Galaxy Classification
• roughly 33% Solar System topics & 67% Stellar & Galaxy topics
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
About the Midterm
• KEY ideas:
• Terrestrial planet characteristics vs. Jovian planet characteristics
• Mars and water on Mars (importance of magnetic fields)
• Venus & Venus’ temperature
• Greenhouse effect/Climate Change
• Saturn’s rings, Jupiter’s “weather”, Io, Ganymede, Callisto, Europa, Titan & Enceladus
• Distances to stars: parallax & standard candles
• Temperature & Color and Temperature & Size & Luminosity for Stars
• Stellar Classification (Harvard Computers)
• HR diagram
• Stellar Evolution
• Galaxy types & Classification
SOLAR SYSTEM
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Sun
• Size compared to earth
• What type of star is the sun?
• Its ultimate fate & that of the solar system
• NOT a supernova!!!!!!!!!!!! NOT!
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Terrestrial Planets in General
• Definition of Terrestrial Planets
• Basic Stats and Key Characteristics
• Rotation and Revolution
• Structure
• Surface
• Current & past habitability
• Formation and Evolution
• Differentiation, Cratering
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Earth
• Terrestrial planets in general; the “habitable zone”
• The Atmosphere -- origin of oxygen
• Water & its role
• Life — unique
• Magnetic field -- dynamo effect
• Greenhouse effect and Climate Change and humans
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Moon
• Characteristics and properties
• size
• cratering
• composition
• Highlands and maria
• Lunar exploration
• Formation — Giant Impact Hypothesis
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Venus
• Temperature!
• Atmosphere -- runaway greenhouse
• Odd rotation
• No magnetic field to speak of
• No moons
• recent (but not current) vulcanism
• Why did Venus become not-habitable?
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Mars
• Cold desert world
• once had abundant surface water
• Minimal magnetic field (no liquid iron)
• very thin atmosphere
• Surface
• N/S differences
• Olympus Mons & other Volcanos
• Valles Marinaris
• two moons
• Exploration -- rovers, Curiosity
• What happened to the water?
• Why is Mars red?
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Jovian Planets
• Common Characteristics
• Size, no solid surface, stripes, rings, lots of moons
• Basic Stats and Key Characteristics
• Rotation and Revolution
• Structure
• Composition -- much like solar nebula
• Magnetic fields
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Jupiter
• Largest planet, 11x diameter of Earth
• Galilean Moons
• Many more moons
• rings -- faint
• Geat Red Spot
• Very strong magnetic field
• Cloud-belt circulation
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Jovian Moons
• Galilean
• Io - currently active volcanos
• Europa -- water under thick ice
• Ganymede -- largest satellite
• Callisto -- most cratered object in SS NASA Planetary Photojournal
“Family Portrait”
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Saturn
• Similar to Jupiter
• Smaller
• weaker magnetic field
• Dramatic Rings
• Shepherd Moons
• Gaps
• Fairly large ice particles
• Up to person sized or so
• VERY thin
• Exploration -- Cassini
Cassini composite image of Saturn
NASA/JPL/Space Science Institute
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Saturn’s Moons
• Titan -- sort of earthlike but with hydrocarbon sludge & nitrogen atmosphere. Cold. Shoreline featurs
• Enceladus -- water ice world, tidal flexing, ice vulcanism
• many more!
• shepherd moons within ring system
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Uranus and Neptune
• Smaller & Colder than Jupiter and Saturn
• Blue/blue green color from methane
• “Wierd” poorly understood Magnetic Fields
• Uranus unusual rotation
• Neptune discovered due to irregularities in Uranus’ orbit
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Dwarf Planets & Small Bodies
• Dwarf Planets
• The Pluto saga
• Meteroid, Meteor, Meteorite
• composition and significance
• Asteroids
• Comets
• The Kuiper Belt
• The Oort Cloud
STARS & GALAXIES
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Stellar Properties
• Luminosity
• Distance ladder & difficulty of distances
• Stellar parallax
• know how angle & distance relate
• Standard Candle
• how does a standard candle work
• Magnitude system
• Apparent vs. Absolute magnitude
• review the ranking tasks
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Spectral Type
• Color ~ temperature ~ spectral class
• be able to answer questions based on the blackbody LT
• Harvard computers & Harvard classification scheme
• OBAFGKM
• Brightness and temperature and size (Giants)
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
HR Diagram
• What is it?
• What can be plotted on it?
• Main sequence
• Red giants
• Supergiants
• White Dwarfs
• Evolution
• Sketch HR diagrams
• Pick out object types on HR diagrams
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Stellar Lifecycles
• Star formation
• Main Sequence lifetime
• End states and what determines them
• Mass is everything!!!!!
• More mass means shorter life
• high mass is > ~ 4 times Sun
• remnant of < 2-3 times sun forms neutron star
• larger remnant forms black hole
© NASA
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Main Sequence & Red Giant phase
• Main Sequence
• Hydrostatic Equilibrium
• H to He nuclear fusion — mass conversion
• Most of a star’s life
• Sun is on MS
• Red Giant
• loss of “engine”
• New hydrostatic equilibrium
• H to He fusion in shell
• He fusion in core
• 1/10th the duration of MS lifetime
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Endgame Scenarios
• Low Mass
• Giant stars
• Planetary nebulae
• White dwarfs
• High Mass Stars
• Type II supernovae
• neutron stars & pulsars
• black holes
• type Ia supernovae
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Galaxy Classification
NASA/ESA
Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015
Characteristics of types
• Describe spirals, barred spirals, ellipticals, irregulars
• identify from image
• Which are most common?
• What are their overall properties?
• Which tend to have older/red or younger/blue stars
• Which tend to have black holes (all)