The earth is the third nearest planet to the Sun. In size, it is the fifth largest planet. Conditions favorable to support life are probably found only on the Earth . The Earth is neither too hot nor too cold. It has air and water, which are very essential for the survival of all living beings. The air has life supporting gaseous like Oxygen, nitrogen and carbon dioxide. Because of these reasons, the earth is a unique planet in the solar system. From the outer space, the earth appears blue because two-thirds of its surface is covered by water. It is , therefore, called a 'blue planet'. The earth is round in shape. It is slightly flattened at the top and the bottom. long ago, people believed that the earth was flat. they thought that they would fall off if they travelled to far to its edges. in 1519, a famous explorer, ferdianand magellan, started his journey around the world. he kept on sailing westwards. after three years in 1522, his ship returned to the same place from where...