PHYS 275 COURSE SUMMARY
Celestial Mechanics [Ch. 3]
- Kepler’s Laws:
I: Elliptical Motion:
II: Law of Areas:
III: Period/Axis Law:
around sun w/ P in years, a in AU
- Centre of Mass:
- Newton’s Gravity:
- Circular & Escape Velocity:
- Vis Viva Equation:
- Tidal Forces – mechanism, Earth-Moon, Jupiter-Io, etc
- Roche Limit:
- Resonances – Mercury, Jupiter, etc
- Lagrange Points – Trojan Asteroids
- Solar Wind – stream of charged particles from sun (nm particles)
- Solar Radiation Force: (mm particles)
- Poynting-Robertson Effect – particles fall inward from friction (mm particles)
- Yarkovsky Effect – bodies thrust out or in by re-radiation (m-km particles)
Formation of Stars, Systems, Planets, and Satellites [Ch. 4,5]
- Cloud Collapse – ISM collapses, core creates protostar, disk formation, fusion
- Virial Theorem:
- Stars as Black Bodies:
[J/s m2]
[J/s]
- HR Diagram & Stellar Evolution – protostar, main sequence, red giant, white dwarf, etc.
- Observational Protostar Evidence:
- Bok Globules – dark clouds diameter 103-105 AU
- Cocoon – dust surrounding forming protostar
- Herbig-Haro – bipolar outflow & disks
- T-Tauri – irregular flaring, protostar emerging from cocoon
- Binary Star Formation – fission, fragmentation, capture
- Pressure in Forming Solar System:
- Scale Height:
- Properties of our SS – age, planet rotation & revolution sense, ecliptic plane, compositions
- Cooling of Solar Nebula – condensation temps of elements match their position in SS
- Planet Formation – chemical condensation, electrostatic clumping, collisional accretion, gravitational buildup, gravity + collisions
- Ring Systems – Saturn’s icy and visible, others carbonaceous & dark
- Moon Formation Theories:
- Fission (but not going that fast!)
- Co-accretion (what about composition differences?)
- Capture (what about composition similarities? also improbable!)
- Giant Impact (best one so far)
Meteorites and Meteoritics [Ch. 6]
- Meteoroid vs. Meteor vs. Meteorite
- Meteorite Types – (1a) stony, chondrite (has glassy “chondrules”), (1b) stony, achondrite (partial melting & crystallization), (2) iron, (3) stony-iron
- Falls vs. Finds – more irons found since more unusual & resistant to weathering
- Radioactive Dating:
On vs. plot, where
- Other Dating Methods – gas retention age, cosmic ray exposure age
- Hypervelocity Impacts:
- Meteorites from the Moon and Mars
Asteroids and Comets [Ch. 7]
- Asteroids vs. Comets – location, observation, orbit, composition
- Asteroid Spectral Classes:
E, S (stony), M (iron), V (basalt), A, C (carbon), P, D, Z (organic)
- Asteroid Shapes – mass vs. shape
- Oort Cloud & Kuiper Belt
- Meteor Showers – caused by comet debris path
- Zodiacal Light – ecliptic dust particles
Planetary Interiors [Ch. 8]
- Bulk & Uncompressed Density:
- Composition by Density: where
- Volume vs. Mass Fraction:
- Moment of Inertia: for
- Differentiation:
- Structure of Earth Interior – surface, lithosphere, moho, aesthenosphere, mantle, core
- Seismology – P Waves (pressure, fast) vs. S Waves (shear, slow)
- Internal Pressure:
- Magnetic Fields – dynamo theory
- Interiors of Inner Planets – Mercury, Venus, Earth, Moon, Mars
- Interiors of Galilean Satellites – Callisto, Ganymede, Europa, Io
- Interiors of Gas Giants – metallic H+, central concentration
Planetary Surfaces [Ch. 9,10]
- Minerals – composition & structure
- Rocks: - Igneous - Granitic (crusts)
- Basaltic (mantles)
ie silicates: feldspar, pyroxene, olivine
- Sedimentary
- Metamorphic
- Surface Evolution – magma ocean, cracks, cratering, volcanism, weathering
- Impact Cratering: - Vs. Time – age of planet, evolution, regolith
- Craters – central peak, walls, slumping, rim
- Factors Affecting – mass, proximity to mass, atmosphere, age
- Volcanism – viscosity, gravitational constant, shield/cinder cone/composite
ie Olympus Mons on Mars largest volcano
- Tectonics – surface movement – slumping, creep
- Plate Tectonics (Earth only)
- Atmospheric Effects – wind & dunes, water & channels
- Surface Temperature: for albedo A, emissivity e,
- Chemical Effects: - Urey Reaction – high temp creates gaseous CO2, water removes it
- Oxidation (ie Mars)
- Surfaces of Inner Planets – Mercury, Venus, Earth, Moon, Mars
- Surfaces of Galilean Satellites – Callisto, Ganymede, Europa, Io
Planetary Atmospheres [Ch. 11]
- Atmosphere Pressure, isothermal: where…
- Scale Height:
- Structure – ionosphere, mesosphere, stratosphere, troposphere (not isothermal)
- Primary Atmosphere (H, He) vs. Secondary Atmosphere (N2, O2, CO2, H20, etc.)
- Gas Retention/Escape:
- Other factors – distribution of speeds, photodissociation, solar wind, etc.
- Dynamics – convection cells, coriolis effect, streamlines, etc.
- Greenhouse Effect – clouds allow UV in, but block IR out (H2O, CO2 mainly)
- Surface Temperature:
- Composition & Evolution of Terrestrial Planet Atmospheres – Venus, Earth, Mars
- Composition & Evolution of Jovian Planet Atmospheres – Jupiter, Saturn, Uranus, Neptune
Extra-Solar Planets [N.A.]
- Doppler Method – measure cyclic velocity variations about CM
– most successful method, to date >100 planets found
- Astrometry Method – observe cyclic change in star position
- Transit Method – observe dimming of starlight as planet passes in front
- Spectral Method – odd bands in spectrum could indicate companion
- Direct Image – detect by observation, big planet large orbits
- Results – many gas giants detected in near-orbits, had to migrate there, but how?
Planet and Satellite Comparisons Summary
Body / Interior / Surface / AtmosphereMercury / - large magnetic field & high density è large molten iron core / - dense cratering
- moreso since close to sun / - none (too small, too close to sun)
Venus / - weak mag. field from low iron & low rotation rate
- some differentiation / - rolling volcanic planes
- many slumping calderas
- very basaltic rocks
- stressed crust / - extremely thick & dense
- CO2, H2SO4 composition
- mega greenhouse effect
- high winds, many storms
- negligible water
Earth / - highly differentiated interior
- defined structure
- plate tectonics
- magnetic field / - weathered by wind and water, sedimentary rocks
- granite rocks / - N2, O2 composition
- near H2O triple point
- past CO2 dissolved in rock
- convection cells, coriolis
- storms present
Moon / - mainly silicate mantle, tiny core (no mag. field)
- homogeneous sphere
- cooled quickly / - dense cratering
- much regolith
- lava flows (maria) / - none (too small)
Mars / - moderate differentiation
- past volcanic activity
- Olympus Mons example / - all basaltic rocks
- lava flows
- red from Fe oxidation
- polar ice caps
- dry channels & beds / - thin
- CO2 composition
- occasional sandstorms
Asteroids / - larger ones partially differentiated
- stony, iron, or stony-iron
- chondrites unaltered – glassy chondrules
- carbonaceous further out / - impact craters and fragmentation / - none (too small)
Jupiter / - gaseous H, liquid molecular H, & liquid metallic H composition
- icy & rocky core
- huge mag. field (met H) / - N.A. / - H, He, NH3 composition
- strong winds & storms
- ie great red spot
- light & dark bands from convection, T gradient
Io / - massive tidal heating
- extremely active interior
- no ice! driven off
- sulfur compounds / - volcanic plumes and volcanos
- most active body in SS / - negligible
Europa / - icy composition
- molten “watery” interior / - very cracked with flows of watery material / - negligible
Ganymede / - icy composition
- highly differentiated
- large mag. field / - ices / - negligible
Callisto / - icy composition (most)
- low density
- undifferentiated
- no mag. field / - ices / - negligible
Saturn / - similar to Jupiter
- less dense / - N.A. / - H, He, NH3 composition
- strong winds & storms
- light & dark bands
Titan / - icy composition
- no mag. field / - unknown (thick atmosphere)
- may be methane water/ice / - extremely thick & dense
- near CH4 triple point
- pressure closest to Earths
Uranus / - similar to Jupiter
- greater % rocky core
- mag. field a mystery / - N.A. / - H, He, CH4 composition
- CH4 absorption causes blue colour
Neptune / - similar to Jupiter
- greater % rocky core / - N.A. / - H, He, CH4 composition
- CH4 absorption causes blue colour
Pluto / - not much known
- icy composition
- not active / - unknown – probably ices / - none known
Comets / - ices w/ carbonaceous material embedded / - outgassing & breakup near sun
- icy/carbonaceous / - only coma (outgassing)
-- Ryan Newson, S2003