Our Earth
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00:00PLANET EARTH
00:07The earth is different from other planets.
00:11We know that the earth is the third planet in the solar system and that it receives sufficient
00:22amount of sunlight for life to exist.
00:28The earth is enveloped by a blanket of air known as the atmosphere.
00:37The atmosphere contains life-supporting gases such as nitrogen, oxygen and carbon dioxide.
00:49The major part of the earth's surface is covered with water.
00:55The presence of sunlight, air and water helps us to survive on earth.
01:05SHAPE OF THE EARTH
01:07In the ancient days, it was believed that the earth was flat.
01:14It was around the 15th century that Christopher Columbus and Ferdinand Magellan undertook
01:23many voyages to prove that the earth was round.
01:30People came to know that the earth was not flat but spherical.
01:38When we observe a ship sailing out to the horizon from the beach, we see the hull disappears
01:46first followed by the mast.
01:52This proves that the ship is going round rather than falling off a cliff.
02:00Now we know that the earth is spherical in shape but flat at the poles and bulging at
02:08the center.
02:12HORIZON
02:14It is an imaginary line where the sky appears to meet the land or sea.
02:23This is possible only if the shape of the earth is spherical or round.
02:33GLOBE
02:34Globe is a model that represents the earth and is spherical in shape.
02:42The word globe is derived from the Latin word globus, which means a round mass or sphere.
02:53A globe facilitates the study of the earth.
02:59It also helps to locate places on the earth.
03:05NORTH POLE
03:07It is the northernmost point on the earth.
03:12SOUTH POLE
03:14It is the southernmost point on the earth.
03:19AXIS
03:20The earth's axis is an imaginary line which passes through the center of the earth joining
03:27the north and south poles.
03:31In the picture, the earth's axis is represented by a dotted line.
03:39The earth moves around the axis which makes it possible for all parts of the earth to
03:46receive sunlight.
03:50This movement is known as rotation.
03:55The arrows represent the direction of the rotation of the earth around the axis.
04:04EQUATOR
04:06The equator is an imaginary line that divides the earth horizontally in two equal parts.
04:15It is halfway between the north pole and the south pole.
04:21The two equal parts are called the hemispheres.
04:27Hemi means half, sphere means round.
04:33The upper half is referred to as the north hemisphere and the lower half is referred
04:41to as the south hemisphere.
04:46CONTINENTS AND OCEANS
04:48The surface of the earth has vast continuous land masses called continents.
04:58The large deep continuous water bodies on the earth are called oceans.
05:07They cover 75% of the earth's surface.
05:14The water of oceans is saline.
05:19CONTINENTS OF THE WORLD
05:22There are seven continents on earth.
05:25They are Asia, Africa, Europe, North America, South America, Australia and Antarctica.
05:43ASIA
05:44Asia is the largest continent on earth.
05:49It occupies one third of the total land mass.
05:56AFRICA
05:57It is the second largest continent.
06:00It was called the dark continent for a long time as not much was known about it.
06:09EUROPE
06:11It is the second smallest continent and lies northwest to Asia.
06:19NORTH AMERICA
06:21It is the third largest continent.
06:24It is twice the size of Europe.
06:29SOUTH AMERICA
06:31It is the fourth largest continent.
06:35IT IS CONNECTED TO NORTH AMERICA BY A NARROW STRIP OF LAND CALLED ISTHMUS OF PANAMA.
06:44ANTARCTICA
06:46Antarctica is a cold, remote continent in the southern hemisphere.
06:52It is nearly twice the size of Australia.
06:59AUSTRALIA
07:00It is the smallest continent in terms of land area.
07:05It is also called the island continent.
07:11A CONTINENT CONSISTS OF MANY COUNTRIES.
07:15For example, India is a part of Asia.
07:20OTHER COUNTRIES LIKE PAKISTAN, CHINA, MYANMAR and NEPAL ARE ALSO A PART OF THE SAME CONTINENT.
07:35AUSTRALIA HOWEVER IS THE ONLY CONTINENT THAT IS ALSO A COUNTRY.
07:43OCEANS OF THE EARTH
07:45The different oceans on earth are Pacific Ocean.
07:51It is the largest and the deepest ocean.
07:55It lies between Asia and Australia in the west and the Americas in the east.
08:05ATLANTIC OCEAN
08:08It is the second largest ocean.
08:11It lies between Europe and Africa in the east and the Americas in the west.
08:21INDIAN OCEAN
08:24It is the third largest ocean.
08:27It lies between Africa and Australia.
08:32It is named after India which lies to the north of the ocean.
08:40BALTIC OCEAN
08:42It is the smallest ocean and lies in the north polar region.
08:50SOUTHERN OCEAN
08:52Is an extension of the Pacific, Atlantic and Indian Ocean.
08:59This ocean encircles the continent of Antarctica.