How it formed?
Billions of years ago, perhaps as a result of a supernova explosion, a large cloud of gas and dust began to fall together. The central part became the Sun and the remainder settled into a spinning disc. Rocky particles formed in the hotter inner parts of the disc, and rocky and icy particles formed in its cooler outer zones. The inner planets, including the Earth formed from rocky particles and the giant planets also pulled in a lot of gas.

Possible way of formation:
1)Supernova Shock Wave
A supernova explosion sent a shock wave hurtling through space. When the shock reached a gas cloud, it squeezed the cloud, which then started to colapse.

2)The Solar Nebula
As the cloud collapsed, it began to spin, and formed a swirling disc of gas and dust called the solar nebula. The center of the solar nebula grew hotter and denser than the surrounding disc, which was hot near the centre but cool at the edge.

3)Building the planets
Small particles began to stick together to from larger clumps, which grew eventually to kilometres across in size. Collisions between these bodies built up the terrestrial planets and the cores of the giant planets.

4)The nebula disperses
As the young Sun became hotter and brighter it blew away the remaining gas and dust. It also blew away the original atmospheres that had formed around terrestrial planets. Farther from the Sun, the giant planets were able to hold on to deep envelops of gas.

5)The Solar System today
The Solar System is now 4.6 thousand million years old. The Sun is a middle-aged star, and the planets have their familiar features.

As the centre of the cloud continued to shrink it becomes globe-shaped and it got heated up. Eventually it became so hot that it started to shine as a star, now known as the Sun. Within the rest of the cloud, over a period of about 100 million years, more and more particles gradually stuck together until the planets and their moons were formed. The giant planets, which formed in the outer part of the cloud, contained icy materials as well as rocky materials. Uranus and Neptune, especially, contained a lot of ice. Each of the giants attracted huge envelopes of gas. Jupiter and Saturn ended up with deep oceans of liquid hydrogen and helium around their cores.

During the formation of the planets and their moons, many rocky bits were left over. Thousands of them, the asteroids, circle the Sun between the orbits of Mars and Jupiter. Many other bits of rock, ice and dust drift far beyond the planets at the very edge of the Solar System, these pieces form comets. Comets probably contain origianl icy and dusty materials that dates back to the birth of the Solar System.

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