About 3000 year ago people believe that the earth was flat. But people wondered why ships disappeared at the horizon. Sailor too returned from journeys and were proof that ships did not fall off the edge of the Earth. The simplest explanation was :the Earth must be round.The final proof come in the year 1522 after the expedition of Ferdinand Magellan,Who was the first to sail around the earth.
Why we do not fall from the Earth ?
Gravity is the force of the Earth that attracts every object toward itself. From our perspective this force always act downwords. For a long time people did not believe that the Earth is round then the people 'underneaath"the sphere would have actually fallen down. In 1687,a physicist issac Newton, prooved that the force of gravity always acts towards the center of the Earth.On the Earth,The force of gravitation always acts 'downwords' irrespect of Eskimos in the Artic region, people in Europe or in habbitants of australa.
What is the atmosphere made up of ?
The word 'atmosphere' means a gaseous cover enveloping a planet. With out atmosphere life would have not been possible on the Earth. One fifth of the atmosphere is Oxygen and four-fifth is Nitrogen. Like the earth interior. The atmosphere too is made up of several layers. All animal and planet lived in the lower most layer of the atmosphere called the troposphere. All weather phenomena take place in the troposphere. Even aeroplanes fly in the outer edge of the troposphere. The stratosphere ,the mesosphere, the iono sphere and the exosphere lie above the traposphere.
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