The Earth: Myth and Reality

The Earth

“The Earth formed has 4.5 billion years ago. The word ‘Earth’ derived from the English and German words ‘ertha’ and ‘erda’ which means ‘ground’. Earth has two geographic poles: the North Pole and the South Pole. These two poles are joining an imaginary line is called Earth Axis. The earth rotates on this titled axis.”

Shape of the Earth: Beliefs to reality:
  • 7th century BCE, the Greek philosopher Thales introduced the concept of a spherical earth was first. He believed that this sphere floated on water.
  • The Greek philosophers Aristotle and Pythagoras established  that the earth is spherical shape. In that time numerous oppositions against this view. Later Copernicus strongly supported this concept.
  • The Indian astronomer Aryabhata strongly believed the shape of Earth to be spherical and that it spins on its own imaginary axis.
  • Years later Magellan’s voyage round the world proved that the Earth is spherical.
  • Sir Issac Newton proved  the Earth is not truly spherical shape, but slightly flattened at the poles and bulged in the middle.                                                                            

Who introduced the concept of Spherical Earth first ?

           -The Greek philosopher Thales.

Who strongly believed the shape of Earth to be Spherical and that it spins on its own imaginary axis?

           -The Indian astronomer Aryabhata.

Who proved that the Earth is Spherical?

           – Magellan’s voyage around the world proved that the Earth is Spherical.

Who proved the Earth is not truly spherical in shape, but slightly flattened at he poles and bulged in the middle?

            -Sir Isaac Newton.

 

What is Geoid?

         The spherical shape of the earth which is slightly flattened at the poles and bulged at the Equator is known as Geoid, means ‘earth-shaped’.

Name the unique shape of the Earth? 

           -Earth is geoid in Geoid.

How big the Earth is!

The Canadian explorer “JEAN BELIVEAU ” trek and sail round the world. He taken 11years for that. In this we can understands how much of  big is our earth. The circumference of this sphere on which we live is about 40000km.

Where on Earth am I?

How can we find out the positon of a thing or region on this spherical and extensive Earth. Is it by drawing lines?

See the figure of the ball given. how can you describe the location of the picture pasted on it? 

  •   At the to
  •   At the bottom 
  •   In the middle 
  •   Along the edge

 

The exact location of places on the Earth is determined based on the latitudes and longitudes.

Lines on the Earth

The location of any region on the earth can be determined based on such a lines. These lines  are drawn at exact angular measurements on the spherical surface.

 

What is the angular measurement of a circle?

Ans) 360°

 Axis

 Insert a straight pole through the centre of a ball and let it spin. This pole is the axis of the ball. Imagine there is a straight pole passing through the centre of the Earth. This imaginary line is the axis of the Earth. The Earth rotates on this tilted axis.

LATITUDES 

Latitude is the angular distance to any point on the surface of the Earth from the centre. By joining the same angular distance.

Latitudes

 

  The longest line of latitude is known as Equator.

  The angular measurement of the equator is  0° .

  The latitudinal circles become smallest to two sides of the equator.

  Latitudinal points are known as North and South Poles.

  Equator (0°), North Tropic of Cancer (), South Tropic of Capricorn (), North Artic circle (), South Antarctic Circle , North Pole (90°), South Pole (90°).

What is Hemisphere

 The Earth divided into two equal halves called Hemisphere. There are usually considered to be four hemispheres: Northern, Southern, Easter and Western. The Equator of 0degrees latitude divides the Earth into the Northern and Southern Hemispheres.

Find out the following:

Q)  Line of  latitude dividing the Earth into two hemispheres?

      Ans) Equator

Q)  Hemisphere to the north of the Equator?

      Ans) Northern Hemisphere

Q)  Hemisphere to the south of the Equator?

      Ans) Southern Hemisphere

Q)  The biggest circle of latitude?

       Ans) Equator

LONGITUDES

The lines connecting both the poles on the globe are the longitudes. These are curved lines perpendicular to the latitudes.

Longitudes

  Longitudes are angular distance East and West of the Standard Meridian.

  Lines of longitudes are imaginary line connecting the same angular distances with reference to the Standard Meridian.

  All the lines of longitudes converge at both the poles.

  There are 180° of longitudes on either side of the Standard Meridian.

  This 180° of longitudes also known as International date line.

Q) What is the angular distance between the Standard Meridian and the line of longitude opposite to it?

Ans) 180°

Q) Identify the lines of longitudes which divide the Earth in to eastern and western hemispheres?

Ans) 0° and 180°

Complete the following table with the help of the globe and the world map.

Country Latitudes Longitudes
1.India Between 8° North and 38° North Between 68° East and 98° East
2.Nepal Between 26° North and 30° North Between 80° East and 88° East
3.The USA Between 24° North and 49° North Between 66° West and 125° West
4.China Between 18° North and 54° North Between 74° East and 135° East

Day and Night

           

                   The shape of the earth is spherical and that it spins on its own axis. The spinning of the earth on its own axis is called rotation. The part of the Earth facing the Sun due to rotation gets illuminated and experiences day. As the opposite face does not get sunlight, night is experienced there. Day and night is experienced one after the other due to the rotation of the Earth. ‘The Earth takes 24 hours to complete one rotation. It is considered as a day’.

              WORKSHEET

Pic

What is called the rotation of the Earth?

          –The spinning of the Earth on its own axis is called rotation.

How to experienced the day and night is one after the other?

          -The part of the Earth facing the Sun due to rotation gets illuminated and experiences day. As the opposite face does not get sunlight, the night is experienced there. Day and night are experienced one after the other due to the rotation of the Earth.

The Earth completes one rotation in ……… hours?

          -24 hours

Sunrise and sunset

The rotation of the earth from west to east that the Sun seems to rise in the east and set in the west. 

WORKSHEET

Draw the Sun at the proper positions with reference to he shadows given.

Changing Seasons

Some changes occur in our surroundings in a single year.

  • Rain
  • Summer
  • Wind
  • Frost
  • Flood
  • Changes in plants.

  Along with the rotation its axis, the earth also moves around the sun. The movement of the earth around the sun  is called Revolution. The revolution of the earth that we experience different seasons.

  All the planets in the Solar System revolve around the Sun.

  The Earth takes to complete one revolution around the sun is 365 1/4days, it is considered as one year.

What is called the revolution of the Earth?

      – Along with the rotation on its axis, the Earth  also moves around the Sun. The movement of the Earth is called Revolution.

Why do the seasonal changes occur?

      -The revolution of the Earth that we experience different seasons.

How many days to takes  the Earth to complete one revolution around the Sun?

        -The Earth takes to complete one revolution around the sun is -365 1/4 days.

The Earth: My lifelong friend

1) The things you like on the Earth

2) The country you like the most its location based on the latitudes and longitudes

  • The repetition of day and nights on the Earth.
  • India
  • The natural phenomenon’s such as rai, snow, etc.
  • Latitudes- between 8° North and 38° North.
  • Sunrise and sunset.
  • Longitudes- between 68° East and 98° East.
  • The beautiful sceneries and creatures on the Earth.

3) Problems faced by the Earth

4) Suggestions to overcome the problems

  • Deforestation.
  • Afforestation.
  • Environmental pollutions.
  • Environmental cleanliness.
  • Natural resource depletion.
  • Prevent natural resources (reduce, reuse, recycle).
  • Climate changes.

 

 

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