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Comets and Meteors, Earth, Jupiter, Light Year, Mars, Mercury, Milky Way, Moon, Nebulae, Neptune, Planets, Pluto, Saturn, Solar System, Star groups, Sun, Uranus, Venus|
Here under Universe, you will find reference information about the Earth, Sun and Universe.
In the ancient times, the earth occupied a central place in the universe. Even Aristotle, the famous, Greek philosopher proclaimed that the earth was the centre of the universe. The sun, the moon and the stars were all subservient to the earth.
It was an important turning point in the history of thought when on January 17, 1610 Galileo, a prominent mathematician of Padua University invented a telescope and proved in a practical way that the Earth like any other planet was an ordinary one and revolved around the sun.
With the advancement of science, the eminence of Earth received more severe blows. For example, from the point of view of size.
Apart from Earth, there are other planets which revolve the sun. These planets are nine in number including the Earth. However, the size, orbit, the period of revolution and rotation, the number of sub-satellites of these planets are different. The solar system consists of the Sun and the nine planets, their satellites and other bodies revolving around it.
The sun, due to its gravitation, attracts these planets towards its centre. If there is no other force, all these bodies will be drawn into the sun and will become part of it. But due to the revolution of these bodies around the Sun, these bodies develop a force opposite to the attracting force; this is called centripetal force and the force acting in opposite direction is called centrifugal force. As a result of balance between them, the planets keep on revolving around in different orbits.
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