Planet: Object that orbits a star that has cleared its neighborhood
Moon: Object that orbits a planet
Asteroids: Chunks of rock that vary in size
Missing
Hadean Eon (4.56 Ga - 4.03 Ga)
- Period of time at the beggining of Earth’s history where it was very hot
- Lasts until the surface cools enough to solidify
- Lots of intense bombardment
- Not many rocks from this time, it was mostly liquid magma, but we do have minerals from 4.4 Ga
Why was earth hot?
- Primordial heat
Accretion: heat produced when planetesimals and proto-planets collided and merged
Core formation: heat released as dense metal segregated into the core which released energy - Radioactive decay
Uranium, thorium, potassium and other unstable isotopes
Planetary differntiation
Random chunks of primordial matter -> interior divided into concentric layers that differ(core, mantle, crust)
Immiscibility (unable to mix): decides if we have layers
Gravity/density: decides on the order of layers if we have layers
How do we know this? Seismic waves from earthquakes
The surface of Earth’s core is liquid but the center is liquid because of the rising pressure.
Earth’s Magnetic Field: created by the inner and outer core, protects the planet from solar winds.
The Earth’s north and south pole are oposite polarities.
add picture of earths magnetic field?
Auroras are caused by the magnetic field
Composition of Earth
Whole Earth: Iron, Oxygen, Silicon (Oxygen + SIlicon = Rock)
Crust: Oxygen, Silicon, Aluminum
Oceanic crust: basaltic, thinner
Continental crust: granitic and thicker
Theory of plate tectonics
Only around since about the 1960s
Can be measured by GPS
Crust, mantle, and core are defined by composition
Lithospehre and asthenosphere are deifned by strength (does it flow)
Plates move due to convection.
Athenosphere heads up and expands
Plates diverse and magma rises between them, and as the magma cools theres a new lithosphere
Plate Boundries
Divergent Boundries
Two plates move away from one another generating new crust.
Convergent Boundries
Colder, denser oceanic plate sinks under the continental plate.
If there are two oceanic or two continenal plates, and the colder/denser one sinks under.
Transform Boundries
Plates slide past one another.
Ex: San Andreas Fault
Different types of Earth Materials
Mineral: Naturally occuring crystalline solids (Ex: Garnet)
Glass: Non-crystaline solid (Ex: obsidian)
Sediment: Acumaltion of loose mineral grains withered from preexisting rocks that become cemented togehter.
Magma & Volatiles: Originate deep from within the Earth
Rocks: Coherent, naturall occuring solid that consists of multiple minerals
- Igneous: solidified molten rock
- Sedimentary: cemented debris of preexisting rocks
- Metamorphic: Altered by high pressure and temperture
Metals: high-density, shiny, and conduct electricity (Ex: Copper, Gold)
Organic Chemicals: carbon-containing compoinds from once-living organisms (Ex: Oil, Coal)
Minerals
What is a mineral?
- Naturally occuring
- Solid substance
- Orderly and repeating crystlaine structure
- Defined, but not set, chemical composition
- Inorganic (No C-H bonds)
How do minerals form?
- As magma cools and crystalizies
- When minerals break down and new ones grow during oxidation
Fun fact: A synthetic diamond is not a mineral because its not naturally occuring.
Water is not a mineral but ice is.