Katie Zheng - 10-28 Geo Notes

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29 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Katie’s
Geonotes

10/14

-

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 enoug
h

-

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

-

Our sun did not form in first cycle of star generation; stops fusing at carbon, canno
t 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 k
m down, iron
-
nickel core

-

We know bec
ause 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 t
o 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

-

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 comp
resses gas in front of it

10/16

-

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, H
2
O, CH
4
, CO
2
, NH
3
, N
2

-

Inner solar system


things start to vaporize

-

Volatility
:
most volatile
-

CH
4
, N
2
, NH
3
, CO
2
, H
2
O, alkali metal
-
rich silicates (1
st

column), other
silicates/metals

-

Refractory


opposite of volatile

-

If things don’t get clumped into plan
ets, 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

-

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 so
lar 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 clump
s, 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

-

Densest in core (metallic), lea
st 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!

10/2
1

-

Mineral


something with a fixe
d 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 ro
ck 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 colo
rs (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)
Flu
orite

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)

-

CLEAV
AGE: direction in which a mineral is most likely to break

-

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

-

LUSTER: the visual texture, how it reflects light

-

Common lusters

-

Vitreous/Glas
sy, 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
crysta
l, SiO
2

-

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

-

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 = A
metrine

-

Chalcedony