How many planets can exist in the universe? (Please tell me all about it)

After the American twin Mars probes "Courage" and "Opportunity" successfully landed on Mars, the desire of human beings to explore advanced life outside their own planet and pursue extraterrestrial habitats has become stronger. Besides the earth, can human beings find an ideal habitat, and can Mars become another habitat for human beings? There may not be an exact answer yet, but some research results may help us make some rational analysis. According to Charles Lineweaver of the University of New South Wales, about 10% of the planets in the Milky Way are suitable for human survival. They established the evolution model of galaxies, and after analysis, they put forward four conditions for the existence of life: the existence of a main star; There are enough heavy metals to form earth-like planets; There is enough time for creatures to evolve; Located in a safe place, it is not exposed to gamma-ray radiation generated by supernova explosion. From this perspective, the Milky Way has a "region where life may exist", which is located in a slowly expanding region 25,000 light years away from the center of the Milky Way. This area includes planets formed between 4 billion and 8 billion years, and three-quarters of them were formed 1 100 million years earlier than the sun. This is only an inference and needs to be proved by facts. Even if this inference is correct, it does not mean that these planets are suitable for human habitation, because the existence of advanced life does not mean that it is suitable for human existence. Secondly, it is a whimsical dream for human beings to run to a planet with a distance of light years. The best candidate may only be the liveliest Mars. The National Aeronautics and Space Administration (NASA) and the American Geographic Society have come to an ambiguous conclusion. Although humans can reach Mars by space shuttle, the conditions that are not conducive to human survival on Mars are still very obvious. Mars is much colder than the earth, with an average temperature of MINUS 40 to MINUS 60 degrees Celsius. There are cosmic high-energy ion radiation and cosmic magnetic field (electromagnetic radiation) on Mars, which is extremely unfavorable to human health. Although they won't kill the people who landed on Mars immediately, the people who landed on Mars received twice as much radiation as the astronauts on the International Space Station. This kind of injury is chronic and fatal. As long as you stay on Mars for a short time, you may suffer from various cancers, cataracts and various diseases after the nervous system is damaged by radiation. Because the gravity of Mars is only 38% of that of the Earth, and the atmospheric pressure is only 1% of that of the Earth, the microgravity environment on Mars is also a challenge to human life and health. In microgravity environment, people's muscles will shrink, bones will become soft due to calcium loss, genes will mutate, people's immune system will be affected, the release of immune B cell antibodies will decrease, and the ability of T cells to identify pathogens and activities will also decrease. In this way, the number of viruses in the human body will also increase, just as the number of viruses in the saliva of astronauts will increase. The recent research conducted by Russian experts on the International Space Station also confirmed that under weightlessness, people's immunity will decline. On October 20, 2003/kloc-0, Russian investigator Caglieri brought immune cells and cancer cells to the space station, and on October 28, 2003/kloc-0, two others brought them back to the ground. This study shows that under microgravity conditions, although the function of individual immune cells is not affected, cancer cells and heterogeneous cells can still be found, recognized and attacked, but the overall immune system of human body will be weakened and degraded under weightlessness conditions. Of course, even with these conclusions, it is not enough to prevent human beings from marching and immigrating to Mars or other planets, because human beings have always been confident and proud: if conditions are not available, they will go ahead when conditions are created. So what conditions can Mars create for human migration? Some people's plan is to build a house in a hidden place like Mars, using building materials that can effectively reduce radiation, and using radiation-proof materials for all clothes. From about 20 15, the environment of Mars is similar to that of the Earth. Of course, it does not rule out that there are other planets whose environment is more similar to the Earth, such as Titan, Saturn's sixth satellite, but it is too far away from the Earth. Other planets are worse than the environment on Mars. Based on the above situation, people can draw the conclusion whether human beings have habitats other than the earth. In 2030, the population on Mars will not exceed 100. The main task is to explore and analyze the climate and radiation conditions on Mars, find the environment for life and its survival, and try to grow crops. From 2030 to 2080, chemical plants and nuclear power plants will be built on Mars, which will have a greenhouse effect and raise the temperature on Mars to several degrees below zero. At this time, scientists, engineers and technicians, doctors and so on all went up. A small number of people will migrate in the third phase. At that time, the temperature on Mars has reached several degrees below zero, plants have grown and formed, the atmosphere has gradually thickened, and carbon dioxide and water can seep out of the ground. Humans don't have to wear protective clothing, but they still have to wear a respirator to breathe. At this time, you can probably move tens of thousands of people. By 2 150, the Martian atmosphere will be formed, with an average temperature of zero degrees Celsius, and crops can be planted and harvested normally. Green plants dissolve and block radiation, and the air is enough for people to breathe. Cities have begun to form on Mars. At this time, it is possible to immigrate to Mars on a large scale.

Recently, according to foreign media reports, Matthew, an astronomer at British Columbia University, said that a planet suitable for human habitation-the red dwarf gliese 58 1c has been discovered recently. "This is the first time that humans have discovered a planet that may be suitable for human habitation outside the solar system. The temperature of this planet is similar to that of the earth, and its size and volume are similar to that of the earth. There may be water on the planet, about 20.5 light years away from the earth (about 120 trillion miles). " Matthew said. Gliese 58 1 Red Dwarf: Its volume is one third of that of the sun, and its temperature is 50 times lower than that of the sun. It is 15 times the volume of the earth, and the temperature is too high to be suitable for life. Gliese 58 1c, a livable planet suspected to be the earth, has a diameter of 1.5 times that of the earth. The planet revolves around a "red dwarf". The "red dwarf" is much smaller than the sun, and it does not have the intense burning heat of the sun. Scientists' basic definition of a livable planet is that it is about the size of the earth, about the temperature of the earth, and has liquid water. As far as the solar system is concerned, Mars is still close to scientists' definition of livability. The news released by astronomers is the first time that planets outside the solar system have been included in the range of livable planets. According to the relevant astronomers, this new suspected livable planet was discovered by an astronomical observation team composed of 1 1 European scientists. Michael, a member of the team and an astronomer at the University of Geneva, said: "This is an important step for us to find extraterrestrial life in the universe. This is a gratifying discovery, but we still have many problems to solve. " Astronomers said that as early as two years ago, astronomers discovered a planet with similar mass to Neptune in Gliese 58 1 system. Later, astronomers discovered a suspected planet in Gliese 58 1 system, which is eight times the mass of the Earth. The discovery of new planets means that Gliese 58 1 will become the first choice for human space navigation in the future. Dimita Sa Sirov, an astronomer at Harvard Smithsonian Center for Astrophysics, said: "This new planet is only 20 light years away from the Earth, and we are fully capable of reaching it." In the search for Gliese 58 1c, Udry and his team used a spectral astronomical telescope with a diameter of 14 1 inch, which was located at the European Observatory. Prior to this, astronomers discovered that the smallest extrasolar planet was six times the mass of the Earth, and the discoverers were Jeff Massey of the University of California at Berkeley and Paul Butler of Carnegie University. Gliese 58 1c orbits the main star Gliese 58 1 once every 13 days, and the orbit is about 7 million miles away from the main star. According to the planetary model drawn by Sa Syrov and his colleagues, it is mainly composed of rocks and water. He said: "The most exciting thing is that the new discovery tells us that there are many such planets. After billions of years of geological movement, such a planet may be more suitable for life than the earth. NASA's upcoming Kepler program may find hundreds of similar planets. " Astronomers speculate that Gliese 58 1c should have an atmosphere, but what is in its atmosphere is still a mystery. If the atmosphere is too thick, it will make the surface temperature of this planet too hot. However, scientists believe that the surface temperature of gliese 58 1c is between zero degrees Celsius and 40 degrees Celsius, which is equivalent to the surface temperature of the earth, so there are probably rivers and oceans on it. Scientists are not sure whether it is a rock structure like the earth or a "big ice hockey" with a liquid ocean on its surface. If it is a "big ice hockey", its surface may be a melting ocean, a "water world" without land. Because the distance between this terrestrial planet and the earth is relatively short, the exploration of this planet will gradually expand with the increase of time. Now that the environmental problems and resource problems of the earth have been exposed, the emergence of new terrestrial planets hopes to bring more long-term development to mankind.