About 5 billion years ago, the solar system was a primitive chaotic world. It is only a part of the gas cloud composed of extremely cold molecules such as hydrogen atoms, carbon monoxide and formaldehyde, and tiny particles of carbon and silicon invisible to the naked eye. This gas cloud is called a dark nebula. The dark nebula contracts due to its own gravity. When it shrinks to a certain density, eddy current appears inside, which makes the whole nebula fall apart and breaks hundreds or even thousands of small nebulae, one of which is the original nebula that forms the solar system.

Because the original nebula was formed in a vortex flow, it was rotated at the beginning. In this way, on the one hand, the original nebula rotates, on the other hand, due to its own gravitational contraction, the nebula gradually flattens, and later a continuous, flat nebula disk with thin inside and thick outside is formed. This is the so-called primitive solar nebula. The density of the central part of this primitive nebula increased during the contraction process, and finally formed its own luminous sun. And dust particles collide with each other and attract each other to form large particles, which attract the surrounding gas and dust, grow up gradually, and finally form a celestial body as big as a planet after about100000 years. This is the formation history of the solar system.