Journey(to(the(Center(of(the(Earth(Earth’s(surface(• Our(experience(with(Earth(is(limited(to(its(surface(• Yet(earth(has(a(complicated(interior(• Earth(is(characterized(by….(• An(internally(generated(magnetic(field(• Solid(and(liquid(surfaces(• A(gaseous(envelope(• A(layered(interior(The(Solar(System(Human(perception(have(changed(• Early(historyFplanets(as(moving(lights(• 1600sF(1st(telescopes(saw(hazy(spheres((• today(a(complex,(evolving(system(Space(probes(have(photographed(and(analyzed(planets((Scientists(have(hypothesized(likely(origins(of(the(solar(system((Earth(and(the(Solar(System(What(would(solar(system(visitors(notice?(• Magnetic(field(• Atmosphere(• Surface(features(• Continents((• Oceans((• Polar(ice(caps(• Evidence(of(humanity(The(Celestial(Neighborhood(• Interstellar(space:(a(vacuum(with(a(virtual(absence(of(matter(• The(amount(of(matter(greatly(increases(approaching(the(Sun(• The(Sun(ejects(matter(outward(into(space(as(the(solar(wind((• Solar(Wind:(Charged(particles(Stream(outward(in(all(directions(Consist(of(protons(and(electrons(• A(small(percentage(of(the(solar(wind(impinges(upon(Earth(Magnetic(Field(The(earth(has(a(prominent(dipolar(magnetic(field(• The(field(has(north(and(south(ends(Magnetic(flux(has(a(direction(that(flows(N(to(S(Magnetic(field(lines(• Extend(into(space(• Weaken(with(distance(• Create(a(shield(around(Earth((the(magnetosphere)(The(Van(Allen(Belts(• The(solar(wind(is(deflected(by(the(magnetosphere.((• Near(the(Earth,(the(stronger(magnetic(field(forms(the(Van(• Allen(belts,(which(arrest(deadly(solar(&(cosmic(radiation.(Aurorae(Some(ions(escape(Van(Allen(belts(• These(ions(are(pulled(to(the(magnetic(poles(• The(ions(create(light(in(the(upper(atmosphere(Spectacular(aurora(follow(solar(flares(• Aurora(borealisF(northern(lights(• Aurora(australis(–southern(lights((The(Atmosphere(• Earth(has(a(well(developed(atmosphere(• Densest(at(sea(level,(the(atmosphere(thins(upward(99%(of(atmosphere(is(below(50km(the(rest(is(between(50(and(500(km.(The(atmosphere(is(layered(• Troposphere((0F~14km)(• Mixing(layer(• Weather(is(limited(to(this(layer((• Tropopause((~14018(km)(• Stratosphere((~18F50km)(Sea(level(atmospheric(pressure(• 1(atm((=1.04(kg.cm2)(• 14.7(pounds(per(square(inch((psi_)(• 1.0(bar(The(atmosphere(is(mostly(nitrogen(Oxygen(was(absent(from(the(atmosphere(before(2.5(Ga(Surface(features(Earth(surface(sis(dominated(by(water(and(land(Water(is(a(part(of(the(hydrosphere(• Surface(water((• Ground(water((• Glacial(ice(Impact(craters(occur(rarely(on(Earth(• Removed(by(weathering(and(erosion(• Unlike(other(planets(in(the(solar(system((Earth’s(surface(reveals(high(continents(and(low(ocean(basins((Position(due(to(the(differing(buoyancy(of(each(type(of(crust((Hypsometric(curve(• Most(land(lies(within(1(km(of(sea(level(• Most(ocean(floors(are(close(to(5km(depth(• Extremes(of(depth(or(height(are(rare(Elemental(Composition(~90%(of(Earth(is(comprised(of(4(Elements(• Iron(35%(• Oxygen(30%(• Silicon(15%(• Magnesium(10%(The(remaining(88(naturally(occurring(elements?(Form(~10%(of(Earth(Earth(Materials((Elements(combine(in(a(variety(of(Earth(materials(Organic(compounds(–CarbonFcontaining(compounds(• Most(are(residue(from(onceFliving(creatures(• Include(wood,(peat,(lignite,(coal,(and(oil(• Geologically(rare((decomposes(in(contact(with(oxygen)(MineralFInorganic(crystalline(solids(• Comprise(rocks(and,(hence,(most(of(the(Earth(• Most(rocks(on(Earth(are(silicates((based(on(Si(and(O)(Glasses(–nonFcrystalline(mineral(like(matter(Rocks(–Aggregates(of(minerals.(There(are(many(types(• Igneous(Fcooled(from(a(liquid((melt)(• Sedimentary(–debris(from(preFexisting(rock(or(minerals(precipitated(out(of(a(water(solution(• Metamorphic(–rock(altered(by(pressure(and(heat(Metals(–solids(made(of(metallic(elements(Melts(–rocks(that(have(been(heated(to(a(liquid(• Magma(–molten(rock(beneath(the(surface(• Lave(–molten(rock(at(the(surface(Volatiles(–materials(that(turn(into(gas(at(the(surface(• Volatiles(are(released(from(volcanic(eruption(A(layered(Earth(We(live(on(the(thin(outer(skin(of(earth(Early(perceptions(about(Earth’s(interior(were(wrong(• Open(caverns(filled(with(magma,(water,(and(air(• Furnaces(and(flames(We(now(know(that(Earth(is(comprised(of(layers(• The(crust((• The(mantle(• The(core((outer(and(inner(core)(Several(clues(indicate(a(layered(structure(Density(• Average(density(greater(than(surface(density(• Density(must(increase(with(depth(Shape(–a(rotating(sphere(requires(centered(mass(• Mass(away(from(center(would(result(in(a(flattened(disk(• Solid(interior(–surface(doesn’t(undulate(from(tidal(forces((Earthquakes(clues(–Earthquake(energy(transmitted(as(seismic(waves(that(pass(through(earth((Seismic(waves(have(been(used(to(probe(the(interior(• Waves(velocity(changes(with(density(• Velocity(changes(give(depth(of(layer(changes(Changes(with(depth(• Pressure(• Temperature(Earth’s(interior(layers(Earth((and(other(planets)(have(layered(interiors(Crust(• Continental(• Oceanic(Mantle(• Upper(• Lower(Core(• Outer(–liquid(• Inner(–solid(The(crust((The(outermost(skin(of(Earth(with(variable(thickness(• Thickest(under(mountain(ranges((70kmF40(miles)(• Thinnest(under(midFocean(ridges((3kmF2(miles)(The(Mohorovicic(discontinuity(is(the(lower(boundary(• Separates(the(crust(from(the(upper(mantle((• Discovered(in(1909(by(Andrija(Mohorovicic(• Marked(by(a(change(in(the(velocity(of(seismic(P(waves(Two(types(of(crust(Continental(crust(–underlies(the(continents(• Average(rock(density(about(2.7(g/cm3(• Average(thickness(35F40(km(• Granitic(in(composition(Oceanic(crust(–underlies(the(ocean(basins(• Density(about(3.0(g/cm3(• Avg.(Thickness(7F10(km(• Basaltic(in(composition((Two(types(of(crust((Crustal(density(controls(surface(position(Continental(crust((• Less(dense(“floats(higher”(Oceanic(crust((• More(dense(“floats(lower”(Crustal(composition(98.5%(of(the(crust(is(comprised(of(just(8(elements(Oxygen(is((by(far)(the(most(abundant(element(in(the(crust(• This(reflects(the(importance(of(silicate(minerals(• As(a(large(atom,(oxygen(occupies(~94%(of(crustal(volume(Earth’s(mantle((• Solid(rock(layer(between(the(crust(and(the( core(•
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