Katie’s Geonotes
10/14
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Dwarfs
White- old dead main-sequence star
Red- smallest, crappiest, barely-stars; nuclear fusion
Brown – giant planets, almost stars
Yellow – our sun, or stars like it
Black – cooled off white dwarfs, none because universe is not old enough
Type 1A Supernova – white dwarf above mass limit, all same brightness, always form from same
parent body, explosion takes seconds
Hubble saw that spiral nebulae are galaxies
Blue shift towards you, red shift away from you
Only one galaxy moving toward us – Andromeda Galaxy
One interpretation: we are stationary, everything else is accelerating away from us
Hubble’s Law, Hubble’s Constant
Another interpretation: universe is expanding, everything appears to be moving away
Spectroscopy – same element will give off same brightness
When two galaxies collide…Starburst!
Milky Way and Andromeda galaxy will in a couple billion years; will form tons of hot young stars
10/15
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Our sun did not form in first cycle of star generation; stops fusing at carbon, cannot fuse oxygen
White dwarf simply contracts
Collapse of main sequence star into planetary nebulae
Earth has iron core; silicon, oxygen, nickel
Sun mostly silicon and oxygen
Solar system formation only form from supernova aftermath
When star gets core of iron 56: explosion – outer shell gets blasted off, several solar masses
blasted and turns into elements, x-rays and gamma-rays
Tc Technetium wasn’t discovered for some time because all isotopes are radioactive
100-2000 km down, iron-nickel core
We know because of magnetic poles; meteorites – most direct chemical argument
Primitive meteorites – look like they haven’t been changed since creation of solar system
Earth seems to have same composition
Technetium is rare – can see decay in these meteorites (able to figure out when solar system
formed)
Creation of star: light source, star starts fusing from clump, gives light pressure, kinetic energy,
gravity
Light pressure – not much effect on Earth (surface area)/(volume); clears out dust particles;
larger effect on smaller part vs. bigger part
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4.568 billion yrs old – age of solar system
Difficult to see: fast compared to age of stars, not many close ones
Dust blocks sight, absorbs light and reemits it as infrared
New infrared telescopes, plan to launch in 2012
Objects at normal temp. give off infrared, very difficult for ground based telescopes for infrared
because mix up with infrared from space
Technically, infinite amount of time for dust to gather, but shock wave- compression waves,
then compressed part compresses gas in front of it
10/16
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Tc-99  Ru-99
Happens in open clusters (burst of star formations); solar system probably formed from
different supernova, violent
Outer solar system is cooler, 50 Kelvin
Liquid or solid: chemical metals, silicate minerals, H2O, CH4, CO2, NH3, N2
Inner solar system – things start to vaporize
Volatility: most volatile - CH4, N2, NH3, CO2, H2O, alkali metal-rich silicates (1st column), other
silicates/metals
Refractory – opposite of volatile
If things don’t get clumped into planets, they get pushed outward by light pressure
Earth- densest planet
If froze atmosphere, would be 10m thick
Helium – attained from natural gas (it forms one atom at a time, a contaminant in natural gas)
Liquid helium – to get things super cold
10/18
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Earth-biggest of the terrestrial planets
Not big enough to hold on to hydrogen or helium- so smaller than outer planets
Runaway process: larger to larger, smaller to smaller; Jupiter – runaway mass
Late Heavy Bombardment – most things that happen to our solar system is dictated by Jupiter
M57 Ring nebula – planetary nebula, white dwarf in center
Open Cluster – lots of clouds of dust, lots of young massive stars
Jupiter great red spot – long continuous cyclonic storm
How to power space probes: 1) solar power 2) plutonium core
M1 Crab nebula – in 1054 the Chinese saw explosion; remnants of a supernova 100 years ago;
now see the light echoes
Planetesimals – mini planets; when proto stellar nebulas start to clump together; initially gentle,
but then bigger clumps, generates heat, then explosion; at higher speeds – melts
Specific gravity – density compared to water; average rock = 3, earth = 6
Gravitational binding energy – energy released
When earth formed – was molten, then cooled
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Densest in core (metallic), least dense crust (silicate rich)
Asteroid – BIG rock in space
Comet – icy body
Meteor – shooting star
Meteorite – former shooting star, now a rock
Meteoroid – rock in space
Can find iron-nickel meteorites with metal detectors (oversampled)
Non iron-nickels are found predominantly in bare deserts or Antarctica
Earth started out dry
Oceans formed from comet impact
Moon created from debris of something very large colliding with earth
MINERALS AND ROCKS!
10/21
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Mineral – something with a fixed chemical composition, crystal structure, and is naturally
occurring
Usually not found in large chunks by themselves
Rocks often made of individual mineral grains
Quartzite(rock) – made up of only quartz (m)
Marble and chalk – both made up of calcite
One class of rock not made of mineral - obsidian; glass is not a mineral – no crystal structure
Basic Properties of Minerals
SHAPE : crystal habit – ideal shape crystal will take on majority of the time if no interference, will
grow in uniform geometric shape
COLOR: but be careful! Quartz – most common, many different colors (due to traces
contaminants); transparent crystals ground up have grain boundaries – opaque
HARDNESS: qualitative scale, what can scratch what
Mohs Hardness Scale
1) Talc 2) Gypsum 3) Calcite 4) Fluorite 5) Apatite 6) Orthoclase 7) Quartz 8) Topaz 9) Corundum
10) Diamond
The Gay Cowboy Found An Old Quaker To Corundum Diamond. Teehee
Fingernails 2-3; typical steel 5-6
Talc- baby powder
Gypsum – plaster, drywall
Fluorite – pretty crystals, main one in fluorine
Apatite – tiny pieces in granite, ore in phosphorous
Orthoclase – pink stuff in granite
Quartz – hardest common mineral, threshold
Star gemstone – polished differently, when light shines on them – forms star (mineral fibers
imbedded inside)
CLEAVAGE: direction in which a mineral is most likely to break
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Mica breaks into sheets, covalently bonded “honeycomb” sheets
Some entirely symmetric, no sheets – 3D structure
Angles chemically determined
Crystal planes and cleavage planes – both shiny flat surfaces
Cleavage planes all parallel, if not – it fractures (breaks in random ways)
Calcite – rhombohedral cleavage
Most rocks fracture
Cleavage more useful than hardness
10/25
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LUSTER: the visual texture, how it reflects light
Common lusters
Vitreous/Glassy, metallic, waxy, druzy, resinous, silky, pearly
Quartz – glassy luster, Hardness 7, no cleavage- very irregular, conchoidial fracture (typical in
brittle substances with no cleavage), color varies widely, grayish-white if pure or clear if one big
crystal, SiO2
Obsidian – best example of conchoidial fracture
Sand dune – sand is quartz (rocks beat up over time)
Quartz is physically/chemically durable
Cryptocrystalline quartz – microscopic grains (e.g. agate, jasper, chert) –flint
Granite – 2 distinct white minerals – quartz and feldspar
Gray – quartz; white – plagioclase; pink – orthoclase; black – biotite
Matte texture – irregular surface
Feldspar – mineral group
10/27
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Widmanstatten Pattern in nickel-iron
Marshian Meteorite (from Mars!); asteroid probably hit mars
Marshian air trapped in them
Looks like rock
Smooth black coating – molten rock
Calcite – obvious distinct cleavage, when perfect- called Iceland Spar
Birefringance – splits image
Hornblende – trapezoidal repeating unit, separated by 56 degrees
Tip of crystal – “Termination” of crystal
Agate – bands of different colors (contaminants); hematite is the reddish brown
Smoky Quartz – caused by radiation damage
Citrine + Amethyst = Ametrine
Chalcedony