Earth Science the prophecy Planet Earth will line

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 22 nd 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. Thales of Miletus Thought that it was a flat disc floating on water. Anagoras Theorized that it was flat and rectangular The Babylonians and Greeks Said it was spherical. Aristotle Proposed a spherical Earth as he observed the curved shadow of the Earth during Lunar Eclipse.

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 Copernicus A Polish astronomer who revived the Heliocentric Theory. Tycho Brahe A 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 Galilei Invented the astronomical telescope that help to establish the Heliocentric Theory and contributed much to the increasing support of the Copernican Theory. Johannes kepler Discovered 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 Erastosthenes 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.

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 sun It 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°

FEATURES of the EARTH it has a density of 5520 kg/m 3(H 2 O has 1027 kg/m 3) 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.

Motions of the Earth Continental Drift - (1 to 8 inches per year) 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) Earth's Rotation on its Axis - (1, 035 mph) Slowing at the rate of 1/1000 second per century. Motion of the Solar System Through the Galaxy (12. 4 miles per second) In the direction of the star Vega in the constellation Lyra. . The Galaxy's Motion Through the Universe (375 miles per second) Revolution Around the Center of the Galaxy (185 miles per second) In direction of the constellation Cygnus. (225 million year cycle)

DIVISIONS OF THE EARTH HYDROSPHERE - the water portion of the planet ATMOSPHERE - the gaseous portion of the planet LITHOSPHERE - the solid portion of the planet

DIVISIONS OF THE EARTH

DIVISIONS OF THE EARTH

LAYERS OF THE EARTH lithosphere core crust outer inner mantle asthenosphere outer inner

Lithosphere Crust v outermost layer v thinnest Ø thickness beneath the ocean is 5 km. Ø thickness beneath continents averages about 30 km. Ø base can be as deep as 100 km. v dense v most rigid/solid v coldest v Quartz (silicon dioxide), feldspar, silicon, magnesium, aluminum Mantle Core v middlemost layer v thicker than the crust Ø 2, 900 km thick v innermost layer v thickest Ø made up of two distinct parts: a 2, 200 km-thick liquid outer core and a 1, 250 km-thick solid inner core v denser than the crust v semi-solid rock v hot v contains more iron, magnesium, and calcium v densest v molten v hottest v metallic (ironnickel alloy)

SUB-LAYER of the CRUST Outer crust/Sial/ granitic layer Inner crust/Sima/ basaltic layer MANTLE asthenosphere SUB-LAYER of the CORE Outer core Inner core