How are planets formed?

/kloc-at the beginning of the 0/5th century, our predecessors used telescopes to observe space and found some bright and hazy celestial bodies, called nebulae for short. These luminous nebulae are composed of a variety of gas and dust components, which have not yet aggregated into real stars. Therefore, it can be said that the prototype of all stars is these nebulae.

One view is that the nebula is slowly shrinking, and in the process of shrinking, the rotation speed of the nebula is rapidly accelerated. Under the action of centrifugal force, its central part protrudes outward and deviates from its original position. These "falling off" parts gather together and finally form a planet. At this time, the nebula slightly in the center is still gathering, thus giving birth to another planet. If this situation continues, planets will gradually form and they will rotate in the same direction.

Another view is that the matter separated from the sun (or the matter falling from other stars) will form a planet when it collides further, and it is only after the stars collide that it is possible to form a planet. Which statement do you prefer?

As we all know, the solar system consists of the most massive stars-the sun and planets. Planets are divided into two categories: inner planets, including Mercury, Venus, Earth and Mars, are mainly composed of rocks; Outer planets, including Jupiter, Saturn, Uranus and Neptune, are mainly composed of gas.

It can be considered that in the early days of the formation of the solar system, more than 99% of the matter converged to the center and became the sun, and some scattered material fragments revolved around the sun. After a long time of collision and gravity, the scattered debris gradually aggregated into nine planets, but at that time the earth was just a chaotic mass with extremely high surface temperature, similar to a fireball.

Later, due to the internal heat, the lighter molten materials in the earth floated up, bringing the tropics to the surface and gradually cooling down. The earth began to evolve into stratification, forming the core, mantle and crust, and the material density gradually decreased from bottom to top. After a long period of time, the gas produced by the chemical reaction inside the earth is ejected and stored around the earth, forming the atmosphere and combining with hydrogen and oxygen to form water. Then through the energy radiation of the sun, the electric and magnetic fields of the earth itself and the suitable living environment, organic matter, that is, the ancestors of all life, is produced from the water.