How are the planets in the universe formed? How many years will it take?

How the planet is formed: At the edge of a star, it may absorb a lot of cosmic dust. Take the sun as an example: about 4 billion years ago, the sun absorbed a lot of dust, and the dust collided and stuck together. For a long time, there are a large number of planetary embryos called planetesimals. At that time, at least billions of planetesimals moved around the sun. The law of interaction between planetesimals is that if the size difference between two planetesimals is large and the speed of each other is not large, after the collision, the small planetesimals will be attracted by the big planetesimals and eaten. In this way, the big planetesimals get bigger and bigger. If two planetesimals are about the same size and have high speed, they will scatter after collision and form many small fragments, and then these small fragments will be eaten by the big planetesimals one by one. In this way, there are fewer and fewer planetesimals. Planets were relatively large planetesimals at that time, and countless asteroids were lucky enough not to be eaten during the annexation period.

It used to be said that in the early days of the formation of the solar system, more than 99% of the matter gathered at 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 the earth at that time was just a mass of chaotic matter. After hundreds of thousands of years, the matter gradually cooled and solidified, forming the original shape of the earth. Hundreds of thousands of years later, due to the gravity of the earth, the gas produced by the chemical reaction inside the earth is stored around the earth, forming an atmosphere, which combines 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 is produced from the water, which is the ancestor of all life. ...

According to the latest statement, some studies think that planets are produced by black holes. And found conclusive evidence for this: the small black hole in the center of the Milky Way can "spray" the planet at super high speed. Prior to this, scientists believed that only supermassive black holes could eject planets at super high speed. Researchers say that in fact, small black holes eject more planets than supermassive black holes. 1988, Jack Hills, a physicist at Los Alamos National Laboratory, predicted that the supermassive black hole in the center of the Milky Way could destroy the balance of twin planets, bind one planet, and eject another planet from the Milky Way at super high speed. Since 2004, astronomers have discovered nine planets repelled by supermassive black holes at high speed. They speculate that this supermassive black hole is 3.6 million times the mass of the sun. However, the research conducted by Ryan O'Leary and Avi Leober of Harvard-Smithsonian Center for Astrophysics in the United States shows that many small black holes in the center of the Milky Way eject a large number of planets. The mass of these small black holes is only about 10 times that of the sun. Some studies believe that there are at least 25,000 small black holes around the supermassive black hole in the center of the Milky Way. When some small black holes eject planets from the Milky Way, they will get closer to supermassive black holes. Leopold said, "Small black holes repel ejected planets faster than supermassive black holes! Studying the trajectory and speed of the ejected planet will help astronomers determine how many black holes will eject the planet and how they repel the ejected planet. " At the same time, they also admit that it is not easy to carry out this research. Existing space telescopes cannot observe the supermassive black hole region in the center of the Milky Way, and there are many small black holes in this region. The researchers speculate that the speed of planets ejected by supermassive matter reaches 709 km/s, and their speed may be slower under the gravitational constraint of the Milky Way. It is estimated that the initial speed of these planets is 1200km/s when they are ejected, but the speed of the planets ejected by small black holes is faster. Under the repulsion of small black holes, the planets can leave the Milky Way at a speed of 2000 km/s.