The earth is the cradle of mankind. For thousands of years, human beings have never stopped exploring the planet where they live. But it was not until18th century that Copernicus put forward the scientific hypothesis of the origin of the earth after Heliocentrism and Newton discovered gravity and the invention of the telescope. The main assumptions of representativeness are as follows:

(1) 1755 German philosopher 1? Kant put forward the nebula theory of the origin of the sun in his book General History of Nature and Theory of Celestial Bodies. Kant believes that the universe and space are dispersed by granular and dispersed primitive matter. Due to gravity, larger particles attract smaller particles and gather to form large and small lumps. After the lump is formed, the gravity also increases, and the aggregation accelerates, and the fruit forms a huge sphere in the center of the diffused lump. Due to the repulsive force and the impact force during polymerization, this huge sphere became a rotating body, forming the original sun. Under the action of the primitive sun, the primitive materials other than the sphere form a flat rotating nebula around the equatorial sun, and the nebula materials gradually gather into lumps of different sizes and gradually form planets. Planets revolve around the sun and rotate under the action of gravity and repulsion. Its model is: elementary particle-lump-planet.

(2) Laplace said 〓 1796 is a French mathematician PS? Laplace independently put forward the nebula theory about the origin of the solar system in his Theory of Cosmic Systems. Laplace believes that the original material of the solar system is a hot spherical nebula, which is much larger in diameter than the current solar system and rotates very slowly. Due to heat dissipation and cooling, the nebula gradually shrinks and becomes dense, and the rotation speed gradually becomes faster. Due to the increasing centrifugal force near the equator, the nebula gradually becomes a nebula disk. When the centrifugal force exceeds the centripetal force, the matter at the equatorial edge separates to form a rotating ring (Laplace ring), and other rings equal to the number of planets are separated one after another. The central part of the nebula eventually formed the sun, and during the rotation of each ring burning the sun, the substances in the ring gradually gathered into some clots to form planets. Similarly, planets separate rings and condense into satellites. This genetic model can be summarized as: hot gas cloud-separation ring-lump-planet.

(3) 〓 Huo Yier-Shazman hypothesis In the 1960s, the British astronomer E? Huo Yier and German astronomer E. Shazman put forward a new hypothesis based on the mechanism of electromagnetic action. They believe that the primitive solar system is a condensed nebula with low temperature and slow rotation. As the contraction intensifies, the rotation speed increases. When it shrinks to a certain extent, the poles gradually flatten, the equator protrudes and throws out matter, gradually forming a disk. After that, the centrosome continued to contract, eventually forming the sun. Because there is a strong magnetic field in interstellar space, the thermonuclear reaction of the sun emits magnetic radiation, which makes the surrounding gas disk become plasma in the magnetic field. When the sun is separated from the disk, the magnetohydrodynamic interaction between them produces a magnetic moment, which transfers the angular momentum of the sun to the disk and makes the disk expand outward. Due to the solar wind, light matter gathers away from the sun to form a wood-like planet, while heavy matter gathers near the sun to form a earth-like planet.

(4) China astronomer Dai Wensai put forward the theory of "nebula" in 123078+0974, which made China's research on the origin of the solar system enter the advanced ranks in the world. Dai Wensai believes that 5.7 billion years ago, there was an interstellar cloud several thousand times larger than the solar system, which caused eddy currents inside the contraction and split into thousands of nebula clusters, one of which formed the original nebula of the solar system. Because the nebula is formed in a vortex, it is rotating at first, with great angular momentum, and contracts due to self-gravity. In the process of contraction, due to the conservation of angular momentum, the rotation speed is accelerated, the nebula is gradually flattened, a lot of energy is released, and the temperature is gradually increased. When the original nebula shrinks to the size of Neptune's orbit today, the centrifugal force at the equator is equal to the gravitational force, and the matter at the equator no longer shrinks, but the contraction inside the nebula continues, thus forming a double concave mirror-shaped nebula disk with thick edges and thin center. The center of the disk has a large contraction density to form the sun, and solid particles of other substances gradually gather into planets through mutual collision and gravitational accretion.