2.1 Earth A Unique Planet

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Earth: A Unique Planetsection 2.1

3 Unique Characteristics1. liquid water on its surface2. lots of O2 in the atmosphere3. can support life

Earth Basics· 3rd planet from the sun· 4.6 billion years old· about 70% of the surface covered in H2O (global ocean)· oblate spheroid - slightly flattened sphere

bulges at equatorpole-to-pole circumference = 40,007 km (24,859 mi)equatorial circumference = 40,074 km (24,900 mi)

· relatively smooth surface· diameter = 12,756 km

Earth's Interior· direct methods of observation

drillinglimited to a few km

· indirect methods of observationseismic waves - vibrations that travel through Earthhelps us determine Earth's interior structure

· 3 compositional zonescrust, mantle, core

· 5 structural zoneslithosphere, asthenosphere,

mesosphere, outer core, inner core

3 compositional zones· crust - 1% of Earth's mass

oceanic crust - under the ocean (5-10 km)continental crust - makes up the continents (15-80 km)part of the lithosphere

· mantle - about 2/3 of Earth's massdenser than crust2,900 km thicklithosphere, asthenosphere, mesosphere

· core - about 1/3 of Earth's massradius 3,500 kmouter core and inner core

5 Structural Zones· lithosphere (crust & mantle)

"litho" - rock, stonesolid, rigid

· asthenosphere (mantle)"astheno" - weak, softsolid, plasticity (flows)allows tectonic plates to move

· mesosphere (mantle)"meso" - middlesolid, strong

· outer core (nickel & iron)dense liquid

· inner core (nickel & iron)dense, rigid, solid

2.1 Earth A Unique Planet

Magnetosphere· magnetic field generated by liquid iron in Earth's core· electric current

force of attraction/repulsion due to movement of chargedparticles (ions)source of magnetismmagnetic fields are created by the motion of chargedparticlesmagnetic fields run perpendicular to electric current

· ANYWHERE there is an ELECTRIC CURRENT there is MAGNETISM!!!!!!!· movement of charged particles in Earth's iron core produce electric currents which creates Earth's magnetic field· shaped by solar wind (charged particles from the sun)

Newton's Law of Gravitation· gravity - force of attraction that exists between all

matter in the universe· law of gravitation - the force of attraction between

2 objects depends on the masses of the objectsand the distance between themlarger mass and closeness increases gravity

· mass has weight (measure of the strength of the pull of gravity on an object; measured in Newtons)

depends on distance from Earth's centeryou would weigh less at the equator than you wouldat the North Pole

· force of gravity decreases as the distance from Earth's center increases

Why do You Weigh More At the North Pole?