Tecchilaw - 1. The Planet Earth We Live

The Earth in which we live can be considered as a marvelous creation of nature. According to the available information, the Earth is the only planet that consists of air and water with a congenial environment for living beings.

The Earth revolves round the Sun while spinning around its own axis. The Earth’s movement around its own axis is called rotation and the journey around the Sun is called revolution. The Earth takes 24 hours or one day to rotate around its own axis and 365 days or one year to revolve around the Sun.

The shape of the Earth

There were different ideas about the shape of the Earth in the past. At present, the Earth has definitely been identified as a spherical object. This is proved by observing the photographs taken from space. (Fi. 1.2)

Although the Earth is considered a spherical object, it is not a full sphere. The reasons are the flatness of the Earth in the Polar Regions and the largeness of the equatorial circumference than the polar circumference. (Fig. 1.3) However, the following data proves that it is only a minor difference.

Latitudes and Longitudes

When observing a geographical globe, you may see a set of lines drawn from North to South and West to East. Those lines are imaginary lines drawn by us and they are called as longitudes and latitudes.

The northern part of the equator is called the Northern Hemisphere and the southern part is called the Southern Hemisphere. The lines to the North of the equator are termed North Latitudes and the lines to its South are termed South Latitudes.

There are some main latitudes among them. Observe figure 1.5 and identify them. Latitude 900 is indicated as a point. The North Latitude 900 is the North Pole and the South Latitude 900 is named the South Pole.

The lines drawn on the globe connecting the North Pole and the South Pole are called longitudes.

The lines drawn to its West are called the West Longitudes and the lines to the East of it are called the East Longitudes.

From the prime meridian 3600 longitudes are distributed and 1800 run towards Eastwards and 1800 run towards Westwards. Therefore, longitude 1800 is common to both the East and West. The International Date Line follows this line. Sometimes, the International Date Line is not marked as a straight line to prevent the division of a country. Observe map1.1 and identify how latitudes and longitudes you have studied are distributed in a world map.

Latitudes and longitudes are used to indicate the location of any place on the Earth specifically and accurately.

Continents and Oceans

71% of the surface of the Earth is covered by water and 29% is covered by land. The areas covered by water consists of Oceans and Seas and the land area consists of continents and islands.

Continents

The Earth consists of seven continents.

Many islands are located around the lands in coastal areas.

There are politically divided countries in each of the continents. However, the continent of Australia is a single country. Observe map 1.3 and identify several countries located in different continents.

Oceans

Japanese Sea, China Sea, North Sea, Red Sea and Mediterranean Sea are several seas located close to lands and Caspian Sea and Aral Sea are located within the continent of Asia.