The Solar System constitutes the Sun and the objects that orbit it directly as well as those which orbit other objects that orbit it directly. These objects include the planets, the dwarf plants and small Solar system bodies like comets and asteroids.
Structure of Solar System
The Sun is the main component of the Solar System, which makes 99.86% of its known mass and dominates it gravitationally. The Sun’s four gas giants (Jupiter, Saturn, Uranus and Neptune) makes 99% of the remaining mass. Out of these four gas giants, Jupiter and Saturn together comprises more than 90%. Therefore, the solid objects of the Solar System together encompasses 0.0001% of the Solar System’s total mass.
The large objects in orbit around the Sun are placed near the plane of Earth’s orbit, called ecliptic. The planets lie very near to the ecliptic. The comets and Kuiper belt of icy objects exist at greater angles to the ecliptic. All the planets and also other objects orbit the Sun in the same direction in which the Sun is rotating, with few exceptions like Halley’s Comet. With the discovery of the Kuiper belt, the outermost parts of the Solar System forms an obvious region comprising of the objects beyond Neptune.
Formation of the Solar System
It is 4.568 billion years ago when the Solar System was formed from the gravitational collapse of a region within a large molecular cloud. This molecular cloud consisted mostly of hydrogen, with some helium. Small amount of heavier elements fused by previous generation of stars was also present in this cloud. The pre-solar nebula, which is the region that would become the Solar System, collapsed, and then the conservation of angular momentum made it to rotate faster. Most of the mass collected in the center, which became tremendously hotter than the surrounding disc. The contracting nebula started rotating faster, and began to flatten into a protoplanetary disc, and a hot, dense protostar in the middle. The planets were formed by accumulation from this disc. Later the dust and gas gravitationally attracted each other, fusing to form huge bodies.