Solar system is collectively the sun with the celestial bodies that revolve around it in its gravitational field. Universe is roughly 13 billions years old and our Solar System is approximately 4.6 billion years old. The solar system formed from rotating cloud of gas and fine dust that collapsed due to the mutual gravitational pull of each piece of matter on every other piece. Scientists believe that these collapsed as the mass of gas and dust were disturbed by the explosion of a nearby star (called Supernova). This explosion (popularly known as big bang explosion) caused waves in the space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. The gas and dust particles are collectively called as Nebulae (singular – Nebula - An immense cloud of gas and dust in interstellar space). The composition of Nebulae is given below: 1) Largely hydrogen and helium – similar to Sun’s composition 2) Dust similar to Earth elemental composition These clouds contracted under force of gravity. This resulted in accelerated rotation and thus formed a flattened disk. After this, immense weight at the center increased pressure. As pressure is directly proportional to temperature, increase in pressure increased the temperature also. This temperature accounted to more than 1,000,000 ºC. Thus fusion began and resulted in formation of Sun. In the outer portion of the disk, materials started cooling and condensing. This formed planets. The inner planets – Mercury, Venus, Earth and Mars consists primarily rocks and metals. Also the volatiles are blown away by solar wind. The outer planets – Jupiter, Saturn, Uranus and Neptune are large having high gravitational attraction. They have rocky cores which are largely hydrogen and helium. The Sun is now a middle aged star, with 9 planets and many other bodies near it in the solar system. In another 5 billion years, scientists think that the Sun will become much larger as energy from within makes the outer layers of the Sun expand, eventually becoming red giant. As this happens, most of the inner planets will be destroyed (including Earth). Eventually, after another 100 million years, the Sun will no longer be able to make energy, and will become a white dwarf, the size of a small planet. |
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