Geo11-02 Planet Earth

8/2/2019 Geo11-02 Planet Earth

1/37

THE PLANET

EARTH


2/37

THE FORMATION OF THE EARTH WAS

AN OFFSHOOT OF THE FORMATION OFTHE UNIVERSE.

Formation of the Universe: Big Bang Theory

Formation of the Solar System: Nebular Hypothesis


3/37

proposed by the Belgian priest Georges

Lematre in the 1920s

Edwin Hubble justified Lematres theory

through observations that the Universe is

continuously expanding; galaxies are moving

away from each other

THE BIG BANG THEORY


4/37

THE SOLAR SYSTEM:leftover from the Big

Bang

the sun

the planets

the satellites and rings

comets and asteroids

meteoroids and dust


5/37

OBJECT PERCENTAGE OF MASS

Sun 99.85%

Jupiter 0.10%

all other planets 0.04%

comets 0.01% (?)

satellites and rings 0.00%

asteroids 0.00%

meteoroids and dust 0.0000001% (?)

COMPOSITION OF THE

SOLAR SYSTEM BY MASS

Source: Abell, Morrison, and Wolff, 1987


6/37

How big are we?


7/37

How small are we?


8/37

How small are we?


9/37

the solar system originated from a single

rotating cloud of gas and dust, starting 4.6

billion years ago, which contracted due to

gravity

the idea was first proposed by Immanuel Kant

and Pierre Simon de Laplace in the 18th

century

THE NEBULAR HYPOTHESIS


10/37

THE NEBULAR MODEL

Time 1

Time 2

Time 3

The Big Bang producedenormous amount of matter:rotating cloud of gas anddust.

The rotating gas-dust cloudbegan to contract due togravity. Most of the massbecame concentrated at thecenter, forming the SUN.

The remaining mattercondensed to form theplanets.

http://www.aerospaceweb.org/question/astronomy/solar-system/contraction.jpg


11/37

SOLAR SYSTEM


12/37

THE SUN

http://www.harrythecat.com/graphics/b/sun23.gif

mostly made up of hydrogen, the principal

product of the Big Bang

suns center became compressed enough to

initiate nuclear reactions, consequently

emitting light and energy (sun became a star)

a middle-aged star


13/37

THE PLANETS

http://mars.jpl.nasa.gov/facts/planets/planets.gif

composition depended on distance from the

sun

planets nearest the sun contained high-temp

minerals (e.g. iron) while those that are far

away contained lower-temp materials (e.g.

methane and ammonia, and some that

contained water locked in their structures)


14/37

Mercury

VenusEarth

Mars

Jupiter

Saturn

Uranus

Neptune

- inner or terrestrial planets(nearest the sun)

- rocky composition: largely silicaterocks and metals (Si, Fe, O)

- giant or Jovian planets (outer planets;far from the sun)

- lack solid surfaces: in gaseous orliquid form

- composition: light elements (H, He,

Ar, C, O, Ni)

Pluto- neither a terrestrial or Jovian planet

- similar to the icy satellites of theJovian planets


15/37

SOME INTERESTING FACTS

1. Planets revolution = counterclockwise

direction.

2. Planets rotation direction the same asdirection of revolution except for Venus,

which rotates in a retrograde direction.

3. Uranus rotates about an axis that aretipped nearly on their sides.

4. Orbital Speed of the Earth = 30 km/s


16/37

THE EARTH

started as dust ball from the nebular gas anddust brought together by gravity (accretion),which was heated (heating) and eventually

segregated into layers (differentiation) as itcooled

when cooling set in, the denser elements(e.g., iron) sank while the lighter ones floatedout into the surface, creating a differentiatedEarth


17/37

CONSEQUENCES OF THE

HEATING & DIFFERENTIATIONOF THE EARTH

1. formation of atmosphere (mostly gases from

volcanic activity)

2. formation of oceans (water released from

crystal structure)

* Life started when atmosphere was modified due

to the appearance of the blue-green algae.


18/37

THE DIFFERENTIATED EARTH


19/37

Crust1. Oceanic basaltic composition (SiMa)

6 to 11 km thick

density: ~3.0 g/cm3

2. Continental granitic composition (SiAl)

20 to 60 km thick

density: ~2.7 g/cm3Oceanic crust

Continental crust

Internal Structure of the Earth


20/37

Mantle extends to a depth of ~2900 km (Fe,

Mg)

1. Upper mantle extends from the base of

the crust

2. Mesosphere lower mantle; from 660 km

depth to the core-mantle boundary



21/37


Core iron rich sphere with small amounts of Ni and

other elementsOuter core

2270 km thick; liquid

Inner core

solid spherewith a radius

of 1216 km


22/37

Discontinuities/Boundaries

1. Mohorovicic crust mantle

2. Gutenberg core mantle

3. Lehmann outer core inner core

From study of seismic

waves


23/37

Mechanical layers1. Lithosphere

a. Upper crust brittle; 4-15 km depth

b. Lower crust/uppermost mantle ductile; 15 to 100 or 200 km depth

2. Asthenosphere weak sphere; beneath

the lithosphere and within the uppermantle3. Mesosphere solid, rocky layer



24/37

THE EARTHS VITAL

STATISTICS


25/37

34.6% Iron29.5% Oxygen

15.2% Silicon

12.7% Magnesium

CHEMICAL COMPOSITION

(by mass)


26/37

SHAPE

Oblate spheroid

flattened at the

poles and bulgingat the equator
http://upload.wikimedia.org/wikipedia/commons/9/97/The_Earth_seen_from_Apollo_17.jpg


27/37

SIZE

Circumference = 360 degrees

800 km 7 degrees

Earths circumference was first

calculated by Eratosthenes


28/37

VITAL STATISTICS

Equatorial Radius = 6378 km

Polar Radius = 6357 km

Equatorial Circumference = 40076 km

Polar Circumference = 40008 km

Volume = 260,000,000,000 cu. milesDensity = 5.52 g/cm3


29/37

THE EARTHS LARGE

SCALE FEATURES


30/37

External Features of the Earth

1. Continents2. Ocean basins


31/37

ISOSTASY

from a Greek word meaning same standing

basically concerned with the buoyancy of the

blocks of the Earths crust as they rest on the

mantle

changes in the load over certain regions

causes the lithosphere to make adjustments

until isostatic equilibrium (i.e., neither rising

or sinking) is reached


32/37

PRATTS THEORY

Elevation is inversely proportional to density.Thus, the higher the mountain, the lower isits density; that is, light rocks floathigher.

depth of compensation


33/37

AIRYS THEORY

Mountains have roots which extend down intothe mantle. Thus, elevation is proportional to thedepth of the underlying root.

depth of compensationrootantiroot


34/37

HOW OLD IS THE EARTH?

Oldest dated Earth rocks: 3.4 to 4.03 b.y.

Meteorites and moon rocks: ~4.5 b.y.


35/37

TRIVIA

Mount Everest (8,848 m)What is the highest elevation on earth?


36/37

TRIVIA

What is the tallest feature on earth?

Mauna Loa (10,203 m)


37/37

TRIVIA

What is the deepest point on earth?Marianas Trench (10,203 m)

Documents

Geo11-02 Planet Earth