Chapter 2 Earth As Planet

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<ul><li> CLASS VIII GEOGRAPHY <ul><li>BR. HECTOR PINTO </li></ul><ul><li>INFANT JESUS HIGH SCHOOL </li></ul></li> <li> Natural Environments: The Atmosphere GE 101 Spring 2007 Boston University Myneni Lecture 03: Rotating Sphere Jan-22-07 (2 of 15) Earth as Rotating Sphere <ul><li>Let us begin to lay the foundation for the first part of the course, which is - </li></ul><ul><li>Energy balance of the earth system </li></ul><ul><li>that is, What energy comes in, how it changes form, what goes out </li></ul><ul><li>The energy source for the earth is the sun. Therefore, we need to look at the earth-sun </li></ul><ul><li> astronomical relationship </li></ul><ul><li>We begin by looking at the earth as a Rotating, Orbiting Sphere </li></ul><ul><li>From this we will be able to answer many questions about the basic climate of the earth </li></ul><ul><li>- Why are there seasons? </li></ul><ul><li>- Why is there such a temperature difference between the equator and poles? </li></ul><ul><li>- What effect does this temperature difference have on the circulation of the </li></ul><ul><li>atmosphere and oceans </li></ul></li> <li> Earth and Moon Presented by Br. Hector Pinto INFANT JESUS SCHOOL, CHALLAKERE </li> <li> SHAPE OF THE EARTH <ul><li>Many speculations about the shape of the earth </li></ul><ul><li>Babylonians thought- earth was circular in shape &amp; surrounded by river Okeanos </li></ul><ul><li>Anaximander regarded earth as cylindrical body. </li></ul><ul><li>Ancient Indians earth was flat with a huge mountain in the middle. </li></ul><ul><li>Pythogoras, Eratosthenes, Arya Bhatta &amp; Ptlolemy earth spherical in shape </li></ul>Earth is geoid in shape </li> <li> Nicolaus Copernicus <ul><li>The Earth moves, in two ways. </li></ul><ul><li>It rotates on an axis (period = 1 day). </li></ul><ul><li>It revolves around the sun (period = 1 year) in same direction. </li></ul></li> <li> The Copernican Model </li> <li> <ul><li>Now not a perfect sphere. </li></ul><ul><li>Flattened at the poles &amp; bulging at the equator </li></ul><ul><li>Named geoid. </li></ul></li> <li> Our Planets At A Glance <ul><li> Earth </li></ul>The Earth is the third closest planet to the sun and the fifth largest planet. It is small and rocky and as far as we know, the only planet that has life on it. About three quarters of the Earth's surface is covered with water and it is the only planet on which water can exist in liquid form on the surface. This is the reason that life can be sustained on it. The Earth is about 4.5 - 4.6 billion years old. It is orbited by one moon. </li> <li> Apollo 17 view of earth </li> <li> The Earth: <ul><li>Only planet which has a biosphere </li></ul><ul><li>-is an oblated sphere, </li></ul><ul><li>-rotates on its imaginary </li></ul><ul><li>axis counterclockwise every </li></ul><ul><li>24 hours or 1 day, </li></ul><ul><li>-appears blue in space </li></ul><ul><li>because it is 70% water, </li></ul></li> <li> Earth is unique:- <ul><li>Has an atmosphere which is rich in oxygen (21%) and nitrogen (77%) </li></ul><ul><li>* presence of oxygen has made life possible on earth. </li></ul><ul><li>* acts as protective blanket around the earth. </li></ul><ul><li>* Ozone layer in the atmosphere absorbs the harmful ultraviolet radiation from the Sun &amp; prevents it from reaching the earth. </li></ul><ul><li>* atmosphere absorbs terrestrial radiation &amp; keeps earth warm during nights and winter. </li></ul><ul><li>* presence of atmosphere reduces extremes of temperature. </li></ul></li> <li> We breathe: <ul><li>78% nitrogen </li></ul><ul><li>21% oxygen </li></ul><ul><li>1% argon, neon, carbon dioxide, neon, &amp; krypton </li></ul></li> <li> <ul><li>2. Has abundance of water 70% of earths surface covered by ocean and seas. </li></ul><ul><li>* called watery planet </li></ul><ul><li>* layer of water is called hydrosphere. </li></ul><ul><li>* water is present in solid and liquid. </li></ul><ul><li>* water appears in gaseous state in the atmosphere also. </li></ul><ul><li>* water is essential for supporting plants, animals and other life forms on earth. </li></ul><ul><li>* water in oceans helps to moderate the temperature conditions on earth which makes the circulation of water possible. </li></ul></li> <li> <ul><li>Layer of rocks which form the surface of the earth is called LITHOSPHERE. </li></ul><ul><li>Lithosphere provides valuable soil layer which sustains all plant life which supports the greenhouse effect </li></ul><ul><li>Plants in turn support directly or indirectly all forms of life on earth </li></ul><ul><li>Also provides all mineral resources needed by us </li></ul></li> <li> <ul><li>The combination of favourable physical environment has made Earth a HABITABLE PLANET. </li></ul><ul><li>Variety &amp; abundance of plants, animals and other forms of life make Earth unique planet. </li></ul><ul><li>No life in other planets </li></ul></li> <li> <ul><li>Various forms of life on earth constitute the BIOSPHERE </li></ul><ul><li>Earth has provided an environment for the evolution of human beings and the progress of human civilization </li></ul></li> <li> How did life begin? <ul><li>It is thought that life began when lightning hit the sea. </li></ul><ul><li>Lightening sent energy into the water. </li></ul><ul><li>Chemicals in the sea were mixed together by energy. </li></ul><ul><li>New substances called amino acids were made from which life was able to grow. </li></ul></li> <li> AMAZING! <ul><li>The first living things on earth were so small you could fit thousands of them on the head of a pin. </li></ul></li> <li> What were the first living things? </li> <li> BACTERIA. <ul><li>They lived in the sea. Some bacteria changed into alage, which were simple plants. Alage lived in the sea in masses, like huge blankets. </li></ul><ul><li>They made oxygen which helped to turn the sky and sea blue. </li></ul></li> <li> ANTIPODAL BALANCE BETWEEN LAND AND WATER <ul><li>There is an anipodal balance of land and water directly opposite sides of the Earth. </li></ul><ul><li>Land on one side of the globe is balanced by water on the other side of the earth. For instance, the North Polar Arctic Ocean is opposite the Antarctic continent. </li></ul><ul><li>Northern Hemisphere is girdled by the land masses of the North America and Eurasia and Southern Hemisphere are the continents of South America, Africa and Australia </li></ul><ul><li>The landmass of Antarctica has three prominent protruding areas one towards South America, another towards South Africa and a third towards Australia </li></ul></li> <li> SHAPE OF THE EARTH <ul><li>In old days, earth was considered to be a flat disc with steep edges. </li></ul><ul><li>All heavenly bodies revolved around the Earth. </li></ul><ul><li>Aryabhatta , famous Indian astronomer, believed Earth was spherical in shape and rotated on its axis. </li></ul><ul><li>In Europe, Greek philosopher Pythagoras and Aristotle were first to state that Earth was spherical in shape. Considerable opposition to this view. </li></ul><ul><li>Now we have convincing evidence from mans landing on the Moon that the Earth is spherical in shape, the evolution of this idea may be considered briefly. </li></ul></li> <li> Proofs for shape <ul><li>LUNAR ECLIPSE:The earth casts a shadow on the moon during a lunar eclipse. This shadow is always semi-circular in shape </li></ul></li> <li> <ul><li>SUNRISE AND SUNSET: The fact that the time of sunrise varies from place to place on the Earth proves that the Earth is not a flat disc. </li></ul><ul><li>If the earth was flat, all places on the earth would have sunrise and sunset at the same time. </li></ul></li> <li> Circumnavigation <ul><li>If we travel around the earth without changing the direction, we arrive at the place we started from. </li></ul><ul><li>As the earth is spherical in shape, it is possible to circumnavigate the earth. </li></ul><ul><li>Magellans crew was first to go round the earth in a ship and complete the voyage without encountering a sharp edge. </li></ul><ul><li>Now aircrafts make many trips round the world on scheduled flights. </li></ul></li> <li> <ul><li>SIGHTING A SHIP: </li></ul><ul><li>When a ship approaches the shore, a person standing on the shore can see the smoke at first and then the chimney and then the ship as a whole. </li></ul></li> <li> ARTIFICIAL SATELLITES <ul><li>The photographs of the earth &amp; other planets sent by the artificial satellites prove that the earth is round. </li></ul><ul><li>Aerial photographs from space show earth spherical. Astronauts have taken pictures of earth from moon showing its spherical shape. </li></ul></li> <li> SHAPE OF THE EARTH <ul><li>Now not a perfect sphere. </li></ul><ul><li>Flattened at the poles &amp; bulging at the equator </li></ul><ul><li>Named geoid. </li></ul><ul><li>At equator diameter measures 12,756 km </li></ul><ul><li>Poles the diameter is 12,714 k.m. giving a difference of 42km. </li></ul>Earth is geoid in shape </li> <li> ) <ul><li>We begin by looking at the earth as a Rotating, Orbiting Sphere </li></ul>12756 km 12714 km N S <ul><li><ul><li>Approximately spherical </li></ul></li></ul><ul><li><ul><li>Actually an oblate ellipsoid </li></ul></li></ul><ul><li><ul><li>Slightly compressed from north to south </li></ul></li></ul><ul><li><ul><li>Slightly bulging from east to west </li></ul></li></ul><ul><li><ul><li>- But, we treat it as a sphere </li></ul></li></ul>Shape of the Earth The Blue Marble </li> <li> SIZE OF THE EARTH <ul><li>Average diameter is about 12,735 km. </li></ul><ul><li>Four planets Mercury, Venus, Mars and Pluto (?) are smaller than the Earth. </li></ul><ul><li>Others are larger </li></ul><ul><li>Early attempt made to estimate the size in 3 rd century BC by Greek philosopher called Eratosthanes. </li></ul></li> <li> Comparison between moon and earth </li> <li> Earths Moon <ul><li>Only natural satellite- avge distance from Earth is 3,84,000km. </li></ul><ul><li>Its diameter is 3470 km </li></ul><ul><li>Moons duration of one rotation is apprx 29 days 5 hours, usually calculated as 29 days </li></ul><ul><li>Revolution around the earth takes approx 27 days and 3 hours- counted as 27 days </li></ul><ul><li>The moons surface is covered in dust and rocky debris from meteor impacts. It has no water or atmosphere. The dark areas of the moon are called maria (Maria is a Latin word meaning seas). Maria are large craters which have been filled by solidified lava. </li></ul></li> <li> Full moon <ul><li>The moon reflects light from the sun onto the earths surface. Sometimes the moon may appear reddish-brown in color as the sunlight is deflected through dust in the earths atmosphere. </li></ul><ul><li>The moons gravitational effects on the earth are most apparent in the coming and going of the tides </li></ul></li> <li> Moon <ul><li>Appears so large because it is so close to earth but diameter is quarter of the Earths diameter </li></ul><ul><li>Experiences extreme of temperature- no atmosphere- its day temperature is 134degree C and night temperature is about -170 C duing two week long lunar night </li></ul><ul><li>Since no atmosphere, no weather conditions </li></ul></li> <li> Surface of the Moon <ul><li>Many craters have been detected on surface </li></ul><ul><li>Some of the mountain ranges like Leibnitz near the Moons south pole has a height of 10670 m-higher than Mount Everest </li></ul></li> <li> <ul><li>Who was the first person to land on the Moon? </li></ul><ul><li>NEIL ARMSTRONG </li></ul><ul><li>Which Year? </li></ul><ul><li>21 st July, 1969 </li></ul></li> <li> Footprint of an astronaut on the surface of the moon <ul><li>Erosion takes place at very slow rate because of lack of rain and wind. </li></ul><ul><li>Footprints will not disappear for many; yeas. </li></ul></li> <li> Apollo 16's Lunar Roving Vehicle parked at the side of the bowl-shaped, 40 metres wide, Plum crater </li> <li> Mars in comparison with Earth Relatively small planet, half the size of the earth </li> <li> I bet you know the answers! <ul><li>What causes day &amp; night? </li></ul><ul><li>Which one is bigger the earth or the moon? </li></ul><ul><li>Where does the moon get its light from? </li></ul><ul><li>What percent of the earth is always lit by the sun? </li></ul><ul><li>How many stars are in our solar system? </li></ul><ul><li>How many days does it take for the Earth to revolve around the sun? </li></ul><ul><li>How many low and high tides on Earth every 24 hours? </li></ul></li> <li> <ul><li>Outline </li></ul><ul><li>the Moon is a bit of an oddball </li></ul><ul><li>formation of the moon, a rough start </li></ul><ul><li>Earths climate </li></ul><ul><li>precession - the Earth as a spinning top </li></ul><ul><li>the Moon and stability of Earths climate </li></ul></li> <li> Where does the moon get its light? </li> <li> It actually gets its light from the sun. How Does it do that? Just like a mirror. </li> <li> PHASES OF THE MOON </li> <li> <ul><li>Phases of the Moon </li></ul></li> <li> GLOSSARY <ul><li>Orbit - The path of the Moon around the Earth. </li></ul><ul><li>Rotate - The Earth spins around, like a top, about its axis once each day. Waning - Shrinking. </li></ul><ul><li>Waxing - Growing </li></ul><ul><li>Gibbous - Swollen on one side </li></ul></li> <li> What causes the phases of the Moon? </li> <li> The phases of the moon are caused by the relative positions of the earth, sun, and moon. The moon goes around the earth, on average, in 27 days 7 hours 43 minutes. </li> <li> MOON PHASES <ul><li>As the moon circles the Earth, the shape of the moon appears to change; this is because different amounts of the illuminated part of the moon are facing us. The shape varies from a full moon (when the Earth is between the sun and the moon) to a new moon (when the moon is between the sun and the Earth). </li></ul></li> <li> Oooh! Aaah! </li> <li> New Moon </li> <li> Waxing Crescent </li> <li> First Quarter </li> <li> Waxing Gibbous </li> <li> Full Moon </li> <li> Waning Gibbous </li> <li> Last Quarter </li> <li> Waning crescent </li> <li> Full Moon <ul><li>A full moon appears as an entire circle in the sky </li></ul></li> <li> Quarter Moon/Half Moon <ul><li>A half moon looks like half a circle. It is sometimes called a quarter moon </li></ul></li> <li> Crescent Moon <ul><li>A crescent moon is part way between a half moon and a new moon, or between a new moon and a half moon. </li></ul></li> <li> New Moon <ul><li>The new moon is the phase of the moon when the moon is not visible from Earth, because the side of the moon that is facing us is not being lit by the sun. </li></ul></li>...</ul>