What do we call a Solar System?- A group of celestial bodies situated in a space of diameter some tens of billions kilometers, which rotate around the Sun on eleptical orbits. Here we include the nine big planets with 32 satellites, around a hundred thousand asteroids( small planets), hundreds of comets and numerous meteor bodies.
The Solar System has perhaps originated in the following way:
In the cloud of cosmic gases and dust, of which the Sun was formed, together with it were formed the other bodies of the Solar System. Besides the main centre(the Sun) which consists of an enormous part of the substance in the cloud (749-750), numerous other centres of accumulation were formed. These were the initial planets. Their masses attracted more and more of the substance around ( cosmic dust and hydrogen gas) and became bigger, till they reached their present dimentions. This process probably began 6-7 billion years ago. This is the age of the Sun, the planets and the Earth.
According to this theory, all planets began their existence as cold bodies, as an initially formless accumulation of cosmic substance. The material from which they were formed contained a lot of radioactive elements. The heat released with their dissociation gradually warmed up the substance. When its temperature reached 1000*C, it became plastic. The elements that weighed more began to sink towards the centre, while the lighter elements emerged onto the surface. According to calculations, the crust of the Earth was formed around 3 billion years ago.
It is
interesting to mention that this process of planet
“formation”, of increasing their masses, has not
stopped, although it is quite weaker now. Till now every day on the
Earth fall some thousand tones meteoric substance. Circumstantial
evidences for the origin of the planets of the cosmic gas are the
giants Jupiter and Saturn, which consist mainly of
hydrogen.
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