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EARTH
Terra firma, globe, macrocosm, old
sod, orb, planet, spaceship Earth,
sphere, sublunary world, Home.
americansector.blogspot.com
Big Bang
In the beginning there is only a super-massive
gaseous point in our empty universe.
Instantaneously and randomly, enough energy is
created to break the gravitational bond holding
this massive body together, exploding the superheated particles throughout space. In less than
one millionth of a second, protons, neutrons,
electrons, and their anti-particles begin to form.
•
http://mediatheek.thinkquest.nl/~ll125/en/bigbang.htm
http://astrocultura.uai.it/tesi/stella2004/Chiara_Donadio/data/img/bigbang.jpg
Big Bang plus Time
• As time moves on, particles begin to
cool by giving off energy, which allows
them to combine to create the first and
most simple ion, hydrogen, as well as a
few more massive atoms.
•
http://mediatheek.thinkquest.nl/~ll125/en/bigbang.htm
Big Bang plus more Time
• More time passes; the atoms are becoming
more abundant in the universe. They begin to
pull together through atomic forces and the
gravitational force.
•
•
http://mediatheek.thinkquest.nl/~ll125/en/bigbang.htm
http://www.eere.energy.gov/hydrogenandfuelcells/education/properties.html
• The Earth was one of the planets formed
from the collapse of the first star. However,
it is unique in many ways. It is the only
planet with visible surface water, which is
explained by the precise temperature and
atmospheric pressure the Earth maintains.
www.esa.int
http://mediatheek.thinkquest.nl/~ll125/en/bigbang.htm
Got Life?
• Earth's atmosphere is also unique, in that
it contains oxygen, which is essential for
life.
Seasons
• The Earth's axis is tilted approximately 23
degrees.
http://physics.uoregon.edu/~courses/BrauImages/Chap01/FG01_013.jpg
Crunch!!!
Or Hit and Run…
• At one time, a large
asteroid may have
collided with the
planet, breaking off a
large piece of it,
which would
eventually become
our Moon.
•
•
http://mediatheek.thinkquest.nl/~ll125/en/big
bang.htm
homepage.smc.edu
Steps in the accretion process:
Step 1: accretion of cm sized particles
Step 2: Physical Collision on km scale
Step 3: Gravitational accretion on
10-100 km scale
anhttp://zebu.uoregon.edu/ph121/l7.html oxygen-silicon crust
http://physics.uoregon.edu/~jimbrau/astr123/Notes/Catastrophes.html
• Step 4: Molten protoplanet from the heat of
accretion.
• Step 5: Final step is differentiation of the earth: Light
objects float; heavy objects sink.
• Iron-Nickel Core (magnetic field), or is it?
A new theory concerning the formation of the core
states that the core may in fact be a nuclear reactor.
•
anhttp://zebu.uoregon.edu/ph121/l7.html oxygen-silicon crust
•
www.fotosearch.com
Things to note about the formation of
planets via accretion
• There is a lot of heat dissipated in the
final accretion process resulting in
initially molten objects.
• Any molten object of size greater than
about 500 km has sufficient gravity to
cause gravitational separation of light
and heavy elements thus producing a
differentiated body.
•
http://zebu.uoregon.edu/ph121/l7.html
The accretion process is inefficient: there is
lots of left over debris.
In the inner part of
the solar system,
the leftover rocky
debris cratered the
surfaces of the
newly formed
planets.
http://www.enchantedlearning.com/subjects/astrono
my/moon/Craters.shtml
Leftovers again?
• In the outer part of the solar
system, much of the leftover
rocky debris was ejected
from the solar system due to
the large masses of the
planets which formed there.
http://www.northstar.k12.ak.us/schools/joy/denali/DAuria/layers.html
How Thick are Earth’s Layer?
The earth’s four layers: the crust, mantle,
inner core, and outer core. The lithosphere
is the crust and the upper part of the
mantle.
The lithosphere is about 5 to 30 miles deep.
The mantle is about 1800 miles thick.
The outer core is about 1300 miles thick.
The inner core is about 800 miles to the
center of the earth.
FOUR MAIN LAYERS
• The earth is divided into four
main layers: the inner core,
outer core, mantle, and
crust. The core is composed
mostly of iron (Fe) and is so
hot that the outer core is
molten, with about 10%
sulphur (S).
http://www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html
The Earth has the Layered Look
• The crust is a thin rocky skin.
The thinnest part of the crust is
under the ocean. The ocean
floor is heavy, dense rock and
the land is lighter, less dense
rock.
•
http://www.northstar.k12.ak.us/schools/joy/denali/DAuria/layers.html
Mantle and Crust
• At over 1000 degrees C, the mantle is
solid but can deform slowly in a
plastic manner. The crust is much
thinner than any of the other layers,
and is composed of the least dense
calcium (Ca) and sodium (Na)
aluminum-silicate minerals. Being
relatively cold, the crust is rocky and
brittle, so it can fracture in
earthquakes.
•
http://www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html
Deep Mantle
• The deep mantle is very hot
because it rides on top of
the extremely hot outer core
and therefore it causes the
mantle and crust to slowly
move.
•http://www.northstar.k12.ak.us/schools/joy/denali/DAuria/layers.html
Inner Core
• The inner core is under such
extreme pressure that it remains
solid. Most of the Earth's mass is
in the mantle, which is composed
of iron (Fe), magnesium (Mg),
aluminum (Al), silicon (Si), and
oxygen (O) silicate compounds.
•
http://www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html
Electromagnetic Field
Electromagnetic Field
• The origin of the Earth's magnetic field
is not completely understood, but is
thought to be associated with electrical
currents produced by the coupling of
convective effects and rotation in the
spinning liquid metallic outer core of
iron and nickel. This mechanism is
termed the dynamo effect.
•
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html
Solar Wind
• The solar wind is a stream of ionized gases
that blows outward from the Sun at about
400 km/second and that varies in intensity
with the amount of surface activity on the
Sun. The Earth's magnetic field shields it
from much of the solar wind. When the solar
wind encounters Earth's magnetic field it is
deflected like water around the bow of a ship,
as illustrated in the following image.
•
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html
Van Allen Belts
• The Earth has two regions of trapped fast
particles. The inner radiation belt
discovered by Van Allen is relatively
compact, extending perhaps one Earth
radius above the equator (1 RE = 6371 km
or about 4000 miles). It consists of very
energetic protons, a by-product of
collisions by cosmic ray ions with atoms of
the atmosphere.
•
http://www-istp.gsfc.nasa.gov/Education/Intro.html
Van Allen Belts
Van Allen Belts become
Radioactive
• The number of such ions is relatively
small, and the inner belt therefore
accumulates slowly, but because
trapping near Earth is very stable,
rather high intensities are reached,
even though their build-up may take
years.
•
http://www-istp.gsfc.nasa.gov/Education/Intro.html
The End
That’s all Folks