Download 2.1 Earth A Unique Planet

2.1 Earth A Unique Planet
3 Unique Characteristics
Earth: A Unique Planet
section 2.1
1. liquid water on its surface
2. lots of O2 in the atmosphere
3. can support life
Click for Earth Video
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 equator
pole-to-pole circumference = 40,007 km (24,859 mi)
equatorial circumference = 40,074 km (24,900 mi)
· relatively smooth surface
· diameter = 12,756 km
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 mass
denser than crust
2,900 km thick
lithosphere, asthenosphere, mesosphere
· core - about 1/3 of Earth's mass
radius 3,500 km
outer core and inner core
Earth's Interior
· direct methods of observation
drilling
limited to a few km
· indirect methods of observation
seismic waves - vibrations that travel through Earth
helps us determine Earth's interior structure
· 3 compositional zones
crust, mantle, core
· 5 structural zones
lithosphere, asthenosphere,
mesosphere, outer core,
inner core
5 Structural Zones
· lithosphere (crust & mantle)
"litho" - rock, stone
solid, rigid
· asthenosphere (mantle)
"astheno" - weak, soft
solid, plasticity (flows)
allows tectonic plates to move
· mesosphere (mantle)
"meso" - middle
solid, 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 charged
particles (ions)
source of magnetism
magnetic fields are created by the motion of charged
particles
magnetic 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 objects
and the distance between them
larger 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 center
you would weigh less at the equator than you would
at the North Pole
· force of gravity decreases as the distance from
Earth's center increases
Why do You Weigh More At
the North Pole?