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EARTH: DYNAMIC, VITAL WORLD

The Earth's atmosphere is about four-fifth's nitrogen and one-fifth oxygen. This abudnance of oxygen is due to the biological processes of life-forms on the planet.

The Earth's atmosphere is divided into layers named the troposphere, stratosphere, mesosphere, and ionosphere. Ozone molecules in the stratosphere absorb ultraviolet light rays.

Teh outermost layer, or crust, of the Earth offers clues tot he history of our planet.

The Earth's suface is divided into hugye plates that move over the upper mantle. MOmvements of the plates, a process called plate tectonics, are caused by convection in teh mantle, and upwelling o fmolten material along cracks in teh ocean floor produces seaflorr spreading. Plate tectonics is responsible for most of teh major features of the Earth's surface, including mountain ranges, volcanoes, and the shapes of the continents and oceans.

Study of siesmic waves (virations produced by earth quakes) shows that the Earth has small, solid, inner core surrounded by a liquid outer core. The outer core is surrounded by the dense mantle, which in turn is surrounded by the thin, low density crust. The Earth's inner and outer cores are composed primarily of iron with nome nickel mixed in it. The mantle is composed of iron-rich minerals.

The Earth's magnetic field produces a magnetosphere that surrounds the planet and blocks the solar wind.

Some charged particles from teh solar winds are tapped in two huge, doughnut shaped rings called the Van Allen radiation belts. A deluge of particles from a coronal mass ejection by the Sun can initiate an auroral display.

THE MOON AND TIDES

The Moon has light-colored, heavily cratered highlands and dark colored, smooth surfaced maria.

Many lunar rock smaples are solidified lava fromed largely of minerals also found in Earth rocks.

Anorthositic rock in the lunar highlands was formed between 4.0 billion and 4.3 billion years ago, wheras the mare basalts solidified between 3.1 and 3.8 million years ago. The Moon's surface has undergone very little geological change over the past 3 billion years.

Impact have been the only significant weathering agent on the Moon; the Moon's regolith was formed by meteoritic action. Lunar rocks brought back to Earth contain no water and are depleted of volatile elements.

Frozen water may have been discovered at the Moon's poles.

The collision-ejection theory fo the Moon's origin, accepted by most astronomers, holds that that young Earth was struck by a huge asteroid, and debris from this collision coalesced to form the Moon.

The Moon was molten in its early stages, and the anothisitic crust solidified from low-density magma that floated to the lunar surface. The mare basins were created later by the impact of planetesimals and were then filled with lava from the lunar interior.

Gravitational and centrifugal interactions between the Earth and the Moon produce tides in teh oceans of the Earth and set the Moon in synchronuous rotation. The Moon is moving away from the Earth, and consequently, the E

In the Solar System today, we have the four inner planets: Mercury, Venus, Earth, and Mars, along with two small moons.

We also have the four outer planets: Jupiter, Saturn, Uranus, and Neptune.

Along with these, we also have asteroids, from the asteroid belt, meteorites, and comets.

ASTEROID

METEOR

COMET

THERE ARE THREE THINGS THAT CAN HAPPEN AS A RESULT OF TWO OBJECTS BEING PULLED TOWARD EACH OTHER BECAUSE OF GRAVITY:

1. They escape from each other.

2. They crash into each other

3. They orbit each other.

STRUCTURE OF THE EARTH

INNER CORE, OUTER CORE, MANTLE (MADE OF PUTTY LIKE ROCK), CRUST, AND ATMOSPHERE

* THE CORE IS MADE OF MOSTLY IRON, AND A BIT OF OTHER HEAVY METALS

* THE MANTLE IS MADE OF LIGHTER MINERALS, IT HAS A PUTTY LIKE SUBSTANCE

*THE CRUST IS MADE OF LIGHTER MINERALS, ON WHICH THE TECTONIC PLATES FLOAT

* THE ATMOSPHERE IS MADE OF 78% NITROGEN, 21% OXYGEN, 1% WATER VAPOR, LESS THEN 1% CARBON DIOXIDE. THE ATMOSPHERE HAS SEVERAL LEVELS- THE BIOSPHERE (WHERE LIFE EXISTS), TROPOSPHERE (WHERE WE GET OUR WEATHER FROM), STRATUSPHERE (WHERE THE OZONE IS THAT PROTECTS US FROM UV RAYS), MESOSPHERE, AND THE IONISPHERE.

*IF YOU SEE IN THE DIAGRAM, WE INCLUDE SOMETHING CALLED THE MAGNETOSPHERE.

THE MAGNETOSPHERE PROTECTS US FROM DEBRIS BLOWN OFF THE SUN CALLED "SOLAR WIND", DENOTED BY THE ORANGE ARROWS.

IN RED, WE ALSO SEE THE VAN ALLEN RADIATION BELT, THIS IS PRECISELY WHERE PARTICLES OF ATOMS REACT WTIH OUR ATMOSPHERE WITH OUR POLES TO CREATE A PHENOMENA CALLED THE AURORA AT EITHER POLE.

THERE ARE SEVERAL PROCESSES WHICH SHAPE THE EARTH'S CRUST:

1. CRATERING- WHERE THE EARTH IS HIT BY SPACE DEBRIS, ALSO KNOWN AS METEROIDS.

2. EROSION- WIPES AWAY CRATERS (WIND, ICE, RAIN, WATER)

3. PLATE TECTONICS- EARTH QUAKES, VOLCANOES, UNDER SEA MOUNTAIN RIDGES

**Why does the Moons surface have many craters and Earth's does not?**

Atmosphere on Earth, but not on Moon. Erosion wipes away the signgs of impact.

We now come to the Moon

ROTATION

A) Moon does rotate, or spin

B) The period of time it takes to roate, is equal to the time it takes to orbit the Earth

C) Because these two period are equal, we only see the visible side of the Moon

TIDES

Oceans on the Earth rise and fall periodically (twice a day, in other words, the ocean moves four times a day)=

2 high tides, 2 low tides

They are a gravitational effect.

SPRING TIDE- THE LARGEST TIDES OF THE MONTH. THIS IS WHEN SUN AND MOON ARE WORKING TOGETHER.

NEAP TIDE- LOWEST TIDES, SUN AND MOON ARE WORKING AGAINST EACH OTHER

THEORIES FOR MOON FORMATION

1) FISSION THEORY- The Earth was very hot and spinning rapidly. Moon split off of it.

2) CAPTURE THEORY- Moon is captured by the Earth because it came too close.

3) CO-CREATION THEORY- Somehow the two closely spaced protoplanets formed with the smaller one in orbit. They grew and eventually became what we know as Moon and Earth.

4) COLLISION EJECTION THEORY- Earth was hit by a Mar's sized object, breaking the Earth completely apart. Most of the material reformed as the Earth, and some material orbitted the Earth, and eventually formed the Moon.

The fourth one, or "collision-ejection" theory is the most widely accepted one, becuase most evidence points towards it, and away from the other three.

1. The capture theory is improbable according to computer simulation.

2. Moon rocks do not have volatile elements, including water. This indicates that Moon rock was superheated at one time, this is consistent with the idea that something hit Earth.

3. Otherwise the rocks are very similar to Earth rocks, in terms of composition.

4. Moon itself has no or very small iron core. When Earth is struck, Moon is formed mostly of crust and mantle material.

CONTINENTAL MOVEMENT

A MAP OF THE WORLD'S TECTONIC PLATES

PLATES- PIECES OF CRUST THAT FLOAT OR GLIDE ON THE MANTLE, PLATE TECTONICS- MOVEMENT OF THESE PLATES

THE CONTINENTS APPEAR TO FIT TOGETHER. THEY EITHER ARE PULLING AWAY FROM EACH OTHER, OR DIVERGENT, IN THE CASE OF SOUTH AMERICA AND AFRICA.

HERE WE ALSO SEE THE MID-ATLANTIC RIDE. THIS IS AN UNDERWATER MOUNTAIN RANGE CAUSED BY PLATE TECTONICS.

PLATES CAN ALSO BE CRASHING INTO EACH OTHER, WHERE ONE PLATE IS GOING UNDER THE OTHER, CALLED SUBDUCTION. THIS IS THE CASE WITH THE SUB CONTINENT OF INDIA AND ASIA, CREATING THE HIMALAY MOUNTAINS.

IN ALL THREE PHOTOS, WE SEE DIFFERENT VIEWS OF WHAT IS HAPPENING WITH THE INDIAN AND ASIAN PLATES

HISTORY OF THE EARTH AND MOON TOGETHER:

1. 4.6 BILLION YEARS AGO- earth is formed from smaller objects coming together, these are called planetesimals. first atmosphere of earth- mostly hydrogen and helium, very thick. but the Earth was too small to keep it, so it left.

2. 4.5 BILLION YEARS AGO- A Mars sized object hits Earth. The Moon is formed from the Debris. The Earth spin period was 5 to 6 hours, now it is 23 hrs, 56 mins. It cooled down and became solid. The Moon did so also, though they were both bombarded by impacts. We also have the second atmosphere of the Earth. Nitrogen and water remain, but there is mostly carbon dioxide. These gasses came from inside the Earth. The Earth becomes differintiated, where the different structural layers are formed. The oceans come from two things: 1. Rain from new atmosphere and 2. comets hitting the Earth. Rain brings carbon dioxide to the oceans, where plant breath it in and release oxygen. Over time we get our third atmosphere. It has nitrogen, oxygen and very little carbon dioxide.

3. 3.8 BILLION YEARS AGO- Major impact on teh Moon and Earth ends. It still continues today, but not to the same extent. About twelve very large objects hit the Moon and from craters. When they hit the Moon, they form mountains on the edge of craters. No plate tectonics on the Moon, mountains are the result of impacts. The craters were filled with lava from below the surface, which is how we have the Dark Maria. We also have the Brighter Highlands.

arth's rotation rate is decreasing.