UPENN Geol 100 Midterm 1

Asteroid

- small rocks moving through space
- most are in asteroid belt between Mars and Jupiter

Comet

- ball of ice and dust and a rock at the center
- form at the edge of the solar system
- when they warm up the ice melts and creates a tail of gas

meteroids

- small particles and fragments orbiting the sun\

meteor

- meteoroid that burns up when entering the atmosphere
- aka shooting star

meteorite

- meteoroid that makes it through to Earth's surface

layers of atmosphere

exosphere
thermosphere
mesosphere
stratosphere
troposphere

Effects of friction in atmosphere

- meteors burn up in mesosphere at 3000 degrees C

How old is the solar system

4.5 billion years old

Planets orbits around the sun

- elliptical
- all counter clockwise
- 3 degrees offset from sun's equator except Mercury's which is 7

attributes of terrestrial planets

- solid and rocky
- low mass
- low escape velocity
- thin atmospheres

attributes of jovian planets

- large and gaseous and low density
- thick atmospheres
- high escape velocity

substances that make up planets

- rocks
- gases (H and He)
- ices (frozen gases and liquids; but not always frozen)

layers of terrestrial planets

crust
mantle (liquid magma)
outer core (liquid)
inner core (solid)

Layers of Jovian planets

outer gases
solid gases
ices
rock at core

ability to retain an atmosphere

depends on temperature (evaporation) and mass (gravity)

inner planets escape velo

5,400-25,000 mph
Earth is 25,000 mph

outer planets escape velo

45,000-143,000

Kuiper Belt

- ring of icy chunks outside Neptune
- includes Pluto
- where short range comets come from

trans-Neptunian objects

Objects that circle the sun beyond the orbit of Neptune
e.g. Neptune, Eris, Makemake

Pluto as dwarf

- only planet discovered by American
- orbit is influenced by neptune which is gravitationally dominant
- orbital incline is 17 degrees
- orbit intersects with neptune but don't collide b/c 3:2 resonance

planet

- celestial body in orbit around the sun
- enough mass and gravity to become sphere
- has cleared neighborhood around its orbit (has its own orbit)

Oort Cloud

- creates sphere around solar system
- made of icy objects and comets
- extends to 3 light years from the sun
- where long range comets come from
- extends to 100,000 AU from sun

Kepler's 3 Laws of Planetary Motion

1. planets orbit in ellipticals
2. planet sweeps out equal areas in equal times and orbital speed is faster when closer to sun
3. orbital period in years ^2 = orbital distance in AU ^3

Harmony of the worlds

planets farther from the sun have to travel further and their orbits take longer because of it

perihelion

orbital point nearest the sun

aphelion

orbital point farthest from the sun

eccentricity

- measurement of how stretched out ellipse is
- 0 is circle and line is 1
- measured by distance between two foci

apigee

point where moon is farthest from earth

perigee

point where moon is closes to earth

eccentricity milankovitch cycle

it takes 100,000 for earths orbit to return to its original eccentricity

axis milankovitch cycle

it takes 41,000 years for earths axis to return to its original degree

precision milankovitch cycle

it takes 23,000 years for the wobble of earths axis to return to its original position

Earth's axial tilt

varies between 22.5 and 24.5 degrees every 100,000 years

makeup of the galaxy

- 90% is H
- 10% is He
- less than .1% is other elements

Nebular Hypothesis

- nebula formed from H and He leftover from big bang and other heavier elements from fusion and other reactions
- says the solar system formed from a large gas nebula of He and H and other elements
- sun got dense and hot enough to start fusion
- small elements and dust circled sun as they collided and formed planets
- inner planets were hot and made of metals and silicates
- outer planets were cold enough for ice and water to form

planetesimals

Small planetary objects that form through the action of gravity during the birth of a solar system

accretion

- accumulation and build up of planetesimals
- creates thermal energy

differentiation

- process by which different elements in planetesimals and planets separated by physical and chemical attributes
- heavy elements sank to core and lighter rose to crust
- lighter elements evaporated and escaped or formed atmosphere
- occurred when planet was still hot enough for metals to melt
- before they are homogenous and after they are layered

3 steps to how planets were formed

1. accretion
2. impact event
3. differentiation

Whole earth elements

- Iron 35%
- Oxygen 30%
- Silicon 15%
- Magnesium 13%

Crust elements

- Oxygen 46%
- Silicon 28%
- Aluminum 8%
- Iron 6%
- Magnesium 4%

age of the universe

13.8 billion years old

stars in a galaxy

varies but average of 300 billion

thickness of crust

40-70 km (depends on ocean or continent)

thickness of mantle

2900 km

thickness of outer core

2270 km

thickness of inner core

1216 km

mantle makeup

oxygen, iron, silicon, magnesium

core makeup

iron and nickel

Moon vs earth

- gravity is 1/6 of Earths (so no atmosphere)
- magnetic field is 1/100 of Earths
- moving away at 1.5 inches per year
- 1/4 size of earth

without a moon

- earth would spin 3 times as fast
- no tides from gravitational pull of moon

How old is the moon

4.5 billion years old

Lunar day

29.5 days

Surface area of the moon

23,559,000 square miles
about same as Africa

formation of the moon

- large protoplanet had glancing collision
- most of earth melted and lots of debris circled
- knocked Earth off axis by 23.5% and sped up earths rotation for a little

lunar highlands

- Light colored mountains on the moon's surface
- made of anorthositic rock (high Al and Ca)
- older than maria and have more craters

maria

- dark flat areas on moon formed by lava coming to surface
- made of basaltic rock (volcanic)
- cover 16% of moon, mostly near side

light side vs dark side of the moon

- dark side has much more highlands
- dark side is 50% thicker

regolith

- very fine lunar soil created by lots of impacts and crushing
- 2 meters deep in maria and up to 20 in highlands
- looking at different layers lets us see changes in solar activity and flares

synchronous rotation

- moon makes one orbit in same time it makes one rotation
- reason we always see near side
- takes 29.5 days
- caused by uneven mass and therefore gravitational pull of moon

tidal forces

- effect of gravitational pull of moon and earth on each other
- cause slight stretching that results in tides
- counteract the self gravitational forces that create spheres

Roche radius

- outside the limit debris comes together to make a moon
- inside the limit a moon would be broken up and form rings

fluid roche radius

18,261 km from earth

rigid roche radius

9,496 km

moon distance from earth

376,587 km
was 22,531 at first

mineral

- naturally occuring
- inorganic solid
- crystalline (long range highly ordered atoms)
- strict chemical makeup (doesn't change) and physical properties

minerology

- study of minerals and their properties
- composition, appearance, stability, occurrence, associations

crystal

- A single, continuous piece of a mineral bounded by flat surfaces
- very uniform molecular makeup

what makes mineral unique

- chemical composition
- atomic arrangement
- types of bonds

ion

- atom that gains or loses electron to then be charged

cation

- positively charged ion
- most are small and usually fit between anions

anion

- negatively charged ion
- most are large and take up most of the space

common cations

Na+
Ca 2+
Al 3+
Si 4+
K+

common anions

O 2-
Cl -
S 2-
F -

different arrangements of ions

- cubic
- tetrahedron
- octahedron

types of chemical bonds

- ionic
- covalent
- metallic

ionic bonds

- formed by electrical attraction between ions of opposite charge
- medium strength
- 90% of minerals

covalent bond

- when two molecules share an electron
- very strong
- eg. diamond
- often include carbon

metallic bond

- formed from metallic cations that are packed together in sea of free electrons
- very conductive because electrons flow through
- strong and flexible
- eg. copper

NaCl

- ionic bond that creates halite
- salt

main types of anions

1) silicate (SiO4) 4-
2) carbonate (CO3) 2-
3) oxide O 2-
4) sulfide S 2-
5) sulfate (SO4) 2-

non-silicate

- does not contain silica
- very weak
- 8% of crust

6 non silicates

1) native elements - normal C, O, Ag, etc.
2) oxide - uses O 2-
3) carbonate - uses (CO3) 2-
4) hydroxide - uses hydroxyl (OH) -
5) halide - uses single anions like Cl-, Fl-, Br-, I-
6) sulfate - uses (SO4) 2-

oxide examples

- hematite Fe2O3
- spinel MgAl2O4
- magnetite Fe3O4
- corundum (ruby)

carbonate examples

- calcite
- aragonite
- dolomite
second most abundant after silicates
major part of limestone

sulfate examples

- anhydride (CaSO4) + 2H20
- gypsum CaSo4

sulfide example

pyrite FeS2

hydroxide example

brucite Mg(OH)2

halide example

halite NaCl
Fluorite CaF2

silicate

- over 90% of earths crust so very important
- contain SiO4

silicon-oxygen tetrahedron

- silicon (cation 4+) atom surrounded by 4 oxygens (anions 2- each)
- total charge of 4-
- basic building block of all silicates
- can balance charge by bonding to cations or sharing electrons w/ other tetrahedrons
- aka silica tetrahedron

silicon oxygen tetrahedron polymerization

- when silica tetrahedrons connect to each other somehow to form crystals

7 types of silicates

1) nesosilicate
2) sorosilicate
3) cyclosilicate
4) Inosilicate 1
5) Inosilicate
6) Phyllosilicate
7) Tectosilicates
NSCIIPT

nesosilicates

- isolated tetrahedra connected by cation
- olivine
- zircon
- topaz

sorosilicates

- isolated double tetrahedra connected at one oxygen
- thortveitite

cycloilicates

- have rings of tetrahedrons
- rings connected by cations
- beryl (emerald)
- tourmaline

Inosilicate 1

- isolated chains of tetrahedra
- aka single chain silicates
- chains don't touch each other but connected by cation
- pyroxene

Inosilicate 2

- connected chains of tetrahedra
- aka double chain silicates
- chains connected to each other at oxygens
- amphibole

phyllosilicate

- sheets of tetrahedra where bottom 3 oxygens connect to others
- aka sheet silicates
- serpentine group
- clay group
- mica group - muscovite, biotite

tectosilicates

- bunch of tetrahedra where all oxygens are connected to another
- if break apart they form phyllosilicates
- aka framework silicates
- quartz
- feldspar group
-64% of crust