Earth Science

the prophecy……

Planet Earth will line up with the Galactic Center of our galaxy as will all the other

planets in our solar system. This happens approximately every 12, 500 years. At this

alignment, energy will bathe our solar system via the black hole at Galactic Center – an extraordinary cosmic event! THIS WILL OCCUR AT THE EQUINOX IN DECEMBER

OF 2012.

Earth Day

Observed every 22nd day of April. Tis was first observed in 1970. What started as a

school campus activity became a worldwide celebration in honor of our planet.

Geology• From the Greek word geo meaning ‘Earth’

and logos meaning ‘study’.

• A science that examines the earth, its form and composition, and the changes it has undergone and undergoing.

Homer (700 B.C.) thought that the Earth was flat.

Proposed a spherical Earth as he observed the curved shadow of the Earth during Lunar Eclipse.

Thales of Miletus

Anagoras

The Babylonians and Greeks

Thought that it was a flat disc floating on water.

Theorized that it was flat and rectangular

AristotleSaid it was spherical.

Astronomical Studies About

Earth

Aristarchus• The first Greek to advocate a sun-centered or heliocentric universe. This

idea was suggested earlier by ARISTOTLE but was rejected because the motion of the Earth around the sun would be demonstrated by a shift in the position of the stars, a phenomenon which was not

observed.

Pythagoras• In the sixth century B.C. Greek

philosopher and mathematician, suggested that the Earth rotates upon an axis and revolves around the sun in its

orbit. He also advocated the Heliocentric Theory that the sun is the center of the

solar system.

Claudius Ptolemy• About the middle of the second century

A.D., Claudius Ptolemy, an astronomer and mathematician of Alexandria,

advanced the Geocentric Theory which placed the Earth at the center of the

universe. This theory describes that all the celestial bodies are moving around the

stationary Earth.

Nicolaus CopernicusA Polish astronomer who revived the

Heliocentric Theory.

Tycho BraheA distinguished Danish astronomer, who

strongly opposed the Heliocentric Theory. He was also responsible for building

pointers used to measure the location of heavenly bodies.

Galileo GalileiInvented the astronomical telescope that

help to establish the Heliocentric Theory and contributed much to the increasing support

of the Copernican Theory.

Johannes keplerDiscovered the three fundamental laws of

planetary motion which describe the Copernican Theory. His physical explanation

was only understood by Sir Isaac Newton.

How old????• Earth is geologically very active, no rocks have been

preserved unchanged since the Earth was formed. Inferred that Earth is about 4.55 billion years old.

• The oldest samples from the Apollo Lunar Missions are approximately 4.6 biliion years old.

• Meteorites and extraterrestial fragments of rocks and metals were examined and found out that they are about 4.6 to 6.4 billion year range.

• The oldest rock in each continent are found to be generally between 3.6 and 3.9 billion years old.

Size and Shape

Greek mathematician and astronomer who estimated the circumference of the earth and the distances to the Moon and sun (276-194 BC).

He did this by measuring the distance between a deep well to Syene and Alexandria and the angle of the moon and sun in Alexandria on the first day of summer. Through mathematical calculations he gave the circumference of the earth was about 43,200 km.

Erastosthenes

Before Isaac Newton, it was believed that the Earth was perfectly round. However, Newton proved that the Earth’s circumference at the poles was less than the circumference at the equator. The scientists agree that the slight bulge is caused by the rapid rotation of the Earth on its axis which makes Earth, spherical.

Analysis shows that the Earth is an oblate spheroid. This means that the Earth is flat at the poles while the equatorial regions are slightly bulging.

Assignment Cite some proofs that the

Earth has a spherical shape.

Motions of the Earth

Rotation on its axis

The Earth spins around on its axis just like a top. The axis is an imaginary line from the top to bottom holes of the Earth. 24 hour period as solar day.

Revolution around the sunIt revolves around the sun in counter clockwise direction. It takes the earth 365.25 days to travel once around its orbit so as to end up in the same position relative to the sun. We call this, a solar year. (365 days, 6 hrs, 9 min. and 10 sec.)

Structures and Composition of the Earth

Most of the Earth's surface (70%) is covered with water, and the remaining 30% is taken up by the seven continental landmasses.

However, underneath the water that fills the oceans, and the dirt and plants that cover the continents, the Earth’s surface layer is

made of rock. This outer layer formed a hard, rocky crust as lava at the surface

cooled 4.5 billion years ago.

• The crust is broken into many large plates that move slowly relative to each other. Mountain ranges form when two plates collide and their edges are forced up. In addition, many other surface features are the result of the moving

plates.

Tectonic Plates• Earth’s crust is broken into about 19

pieces

• These plates move on top of the asthenosphere

Inside the Earth

Composition (What it is made of)

• Crust

• Mantle

• Core

The Crust

• Outer layer• 5-100 km thick• 2 types of crust

– Oceanic (very dense, made of basalt)

– Continental (less dense, made of granite)

Oceanic and Continental Crust

The Mantle

• Middle layer• Very thick layer

The Core

• Made mostly of iron

• 1/3 of the earth’s mass

• Very hot

Earth’s Layers• How are the earth’s

layers similar to an egg?

• Shell=crust• Egg white=mantle• Yolk=core

Physical Structure of the Earth(5 Layers)

• Lithosphere- rigid outer layer (crust)

thin silicate rock material

• Asthenosphere- solid rock that flows slowly (like hot asphalt)

• Mantle - middle layer

• Outer Core- liquid layer

• Inner Core- solid, very dense

FEATURES of the EARTH

is the third planet from the sun in the Solar System

is the only planet in the solar system that support life

is the fifth largest planet in the Solar System

is the densest planet in our Solar System

is 4.5 billion years old

it has one moon which is about one quarter of the diameter of the Earth

its axis is tilted at 23.45°

it has a density of 5520 kg/m3(H2O has 1027 kg/m3)

it takes the Earth 23.93 hours to rotate around its axis

it takes the Earth 365.26 days to orbit the sun once

it has a diameter of 7,926 miles(12,756 km)

it has a mass of 5.98 x 1024 kg.

FEATURES of the EARTH

Motion of the Solar System Through the Galaxy (12.4 miles per second) In the direction of the star Vega in the constellation Lyra..

Motions of the EarthContinental Drift - (1 to 8 inches per year)

Earth's Rotation on its Axis - (1,035 mph) Slowing at the rate of 1/1000 second per century.

Precession of the Earth's Axis - (26,000 year cycle)By 14,000 A.D. the star Vega will replace Polaris as the North Star

Earth's Revolution Around the Sun (19 miles per second)

Revolution Around the Center of the Galaxy (185 miles per second)In direction of the constellation Cygnus. (225 million year cycle)

The Galaxy's Motion Through the Universe (375 miles per second)

LITHOSPHERE

DIVISIONS OF THE EARTH

HYDROSPHERE

ATMOSPHERE

- the water portion of the planet

- the gaseous portion of the planet

- the solid portion of the planet

DIVISIONS OF THE EARTH

DIVISIONS OF THE EARTH

LAYERS OF THE EARTH

core

mantle

lithosphere

crust

asthenosphere

outer inner

outer inner

LithosphereCrust

Mantle Core

v   outermost layerv   thinnest thickness beneath

the ocean is 5 km. thickness beneath

continents averages about 30 km.

base can be as deep as 100 km.

v   densev   most rigid/solidv   coldest Quartz (silicon

dioxide), feldspar, silicon, magnesium, aluminum

  

v   middlemost layerv   thicker than the crust 2,900 km thick      v   denser than the crustv   semi-solid rock v   hotv     contains more iron, magnesium, and calcium

v   innermost layerv   thickest made up of two distinct parts: a 2,200 km-thick liquid outer core and a 1,250 km-thick solid inner core

 v   densestv   moltenv   hottestv   metallic (iron-nickel alloy) 

SUB-LAYER of the CORE

Outer core

Inner core

SUB-LAYER of the CRUST

Outer crust/Sial/ granitic layer

Inner crust/Sima/ basaltic layer

MANTLE

asthenosphere