1: basics of earth Flashcards
What is a planet?
International Astronomical Union (IAU) 2006
Official people in charge
Planets must be:
Must be in orbit around the Sun (not around another object)
Must be massive enough to be rounded by its own gravity
Must be a sphere
Must have cleared the neighborhood around its orbit
IAU’s Solar System
Sun
Eight planets
Other stuff
Many dwarf planets* and moons
>3 “Dwarf Planets”(not actually considered planets): Ceres, Pluto, Eris
Satellites
Millions of asteroids and comets
the big bang
The Big Bang
All matter and energy in the Universe started out as a single infinitesimally small point
It exploded and has been expanding since
simple atoms in big bang
Protons
Neutrons
Electrons
H and He
Formed in Big Bang
element vs isotope
Element: Unique number of protons in its NUCLEUS
Isotope: Different numbers of neutrons for a given element
Stellar nucleosynthesis
Lightest elements (H, He, Li) formed during the Big Bang
Elements up to Fe (atomic number 26) formed in stars
Stellar nucleosynthesis
Elements larger than Fe formed during supernovae
Death of a Star
Very heavy elements (atomic number >26) form during supernova explosions
This is the Crab Nebula
Rapidly expanding shell of gas from an explosion whose light reached the Earth in 1054 CE
Formation of the solar system
4.6 Ga
Gas and debris (from previous generation stars)
Condenses into protoplanetary disk
Center of the disk ignites into nuclear fusion
Dust in the rings of disk coalesce into planetesimals
Planetesimals into planetoids
Dust particles and stony debris accumulate to create a lumpy planetoid
Interior of the planetoid heats up to melting
Allows the body to become spherical
Allows heavy (dense) materials to move to the middle
Differentiation!!!! over time physical and chemical layers of planet seperate
Earth’s unique nature
Near circular orbit
Just right size
Just right place
Plate tectonics
Magnetic field
Ozone layer
Axial tilt at 23.4°
Moon
Jupiter
Differentiation of Earth’s spheres
(Magnetic field)
Atmosphere
Hydro/Cryosphere
Biosphere
Geosphere/Lithosphere
-Crust
-Mantle
-Core
Atmosphere`
air
Hydro/cryosphere
ice and water above ground
biosphere
plants and animals
Geosphere
under everything differentiated by chemical and physical properties
Iron and oxygen followed by magnesium and silicon make up most of the earth’s mass
How can scientists determine ANYTHING about the center of the earth
earthquake waves: monitored due to things like the cold war
Earthquakes generate several different types of waves.
P-waves can move through solids and liquids
S-waves can only move through solids
S-wave shadow zone indicates a liquid outer core
Earth’s crust: continental
Two kinds of crust
Continental crust
Thicker
Older
Less dense
Earth’s crust: oceanic
Oceanic crust
Thinner
Younger
Denser
Stretching and mountain building
stretching thins crust, mountain building thickens crust
Why are the oceans mostly covering the oceanic crust?
Ocean crust is thinner and denser, so it is always at lower elevations
Earth’s crust chemical composition
mostly oxygen (93%), then silicon, aluminum, iron
Interior: Mantle and Core
Mantle
Largest layer by thickness
Composed of two sublayers
Upper mantle
Lower mantle
Convection transfers heat from the interior to the surface
Core
Densest layer
Composed of iron-nickel alloy
Composed of two sublayers
Outer core—LIQUID
Inner core–solid
what creates the earth’s magnetic field
Convection in the outer core creates Earth’s magnetic field
How do we know? about the inner layers of the earth
Pieces of the upper mantle have been dragged up in explosive volcanic eruptions
The density of the earth requires an iron metal core
Some meteorites from the destruction of small planetoids show core/mantle characteristics
Two ways of looking at the layers of the world
Chemical properties
-Crust
-Mantle
-Core
Physical properties
-Lithosphere
-Asthenosphere
-Mesosphere
-Outer Core
-Inner Core
Layers of the Earth: Physical Properties Version
AS you go down pressure and temperature increase. The differences in states of matter of these payers are decided by whether temp or pressure wins at that spot: increased temp cause liquids increased pressure causes solids:
Lithosphere: Solid
Asthenosphere:
Partially solid, partially liquid
Mesosphere: Solid
Outer Core: liquid
Inner Core: solid
Chemical Layers
Crust
-Silicate rocks: Silica and alumina
Mantle
-Silicate rocks: Abundant iron and magnesium
Core
-Iron and nickel
Earth-related problems society faces
Climate change
-Global warming
-Rising sea levels
-CO2 emissions
-Melting ice caps
Depletion of natural resources
-Non-renewable energy sources
-Energy shortage
-Decrease in oil
-Deforestation
Pollution
-Water contamination
-Solar panels in landfills
-Industrial waste
-Consumer waste
Fresh water depletion
Droughts
