Half a century ago, with the rapid development of human industry, we finally realized the dream of flying and walked out of the earth. When human beings go out of the earth, the exploration of extraterrestrial life has become a very important research project. From the perspective of the vast universe, theoretically, the earth is not the only living planet.
The existence of extraterrestrial life should be a high probability event, but before we really found extraterrestrial life, all kinds of problems about extraterrestrial life are just conjectures. In order to turn this conjecture into reality, scientists began a lot of observation and research, hoping to find a second life planet.
Because we know nothing about extraterrestrial life, when we explore and search for extraterrestrial life, we basically look for it based on the earth. The earth can become a life planet with rich species, which shows that the earth must have all kinds of natural advantages and all kinds of conditions for the birth of life.
Scientists divide these conditions into internal and external factors. The internal factor is the perfect ecosystem of the earth itself, such as a thick atmosphere, a strong magnetic field, a large amount of liquid water on the surface and a variety of rich mineral elements. The external condition is that the distance between the earth and the sun is very suitable, that is, in the livable zone.
Only in the habitable zone of the planet, the surface can have a lot of liquid water resources, and water is the source of life. If there is no liquid water on the earth’s surface, it is possible that early life will not be born and it will not be a life planet. Besides the earth, there are Venus and Mars in the habitable zone of the solar system. However, the surface environment of these two planets is very bad.
Venus’s atmosphere is mainly composed of carbon dioxide, the greenhouse effect is particularly serious, so the surface temperature is as high as 460 degrees Celsius. At such a high temperature, it is impossible to have a large amount of liquid water. Mars is located at the edge of the habitable zone, with low temperature, very thin atmosphere, and its surface is basically a desert. There is only a small amount of ice water at the two poles, which shows that the probability of life on Venus and Mars is very low.
The probability of life on other planets outside the habitable zone is even lower. Therefore, scientists mainly focus on exploring life outside the solar system. We should know that the solar system is only one of the 100 billion star systems with Galactic coefficient, and each star system has a habitable zone, and there may be several earth like planets. As long as the conditions are suitable, the probability of liquid water on the surface of these earth like planets in the habitable zone is very high, and with water, life is possible.
Through the continuous improvement of scientists’ understanding of the universe in recent years, we can draw a conclusion that water is a universal substance in the universe. There may be a lot of water in every stellar system. For example, there are many planets with water in the solar system. However, the surface of planets outside the habitable zone can only exist in the form of ice. Only the surfaces of planets in the habitable zone are likely to have large amounts of liquid water.
Scientists are looking for planets outside the solar system where there may be a lot of liquid water. Their first goal is to find the habitable zone of stars. There is no doubt that some earth like planets very similar to the earth are more likely to have life. The discovery of one of the exoplanets once again gives us hope. The exoplanet is named k2-18b.
K2-18b is 124 light-years away from the earth. Its radius and mass are 2.6 and 8.6 times that of the earth, respectively, and it is located in the habitable zone of its star. Last year, a scientific team detected water vapor in the k2-18b atmosphere, causing a sensation in the astronomical community. But scientists didn’t know the thickness of k2-18b’s atmosphere or the interior of the planet.
The atmosphere of this exoplanet is very thick. If there is water vapor in its atmosphere, there is a high probability that there will be liquid water resources on its surface. Some scientists believe that k2-18b is more like a “mini” Neptune, and its atmosphere may have a layer of hydrogen. If the hydrogen layer is too thick, the surface temperature and pressure of the water layer below it will be too high to make life impossible.
Of course, this is only the preliminary exploration results of scientists. Because this exoplanet is far away from us, it is difficult for us to really understand its atmospheric structure through some observation data, let alone accurately understand its surface. Therefore, we can only make a variety of guesses about some of its conditions. No matter what, it can show a distinctive style, which is obviously different from other earth like planets. Then such planets are worthy of our high attention.
Some scientists think that it is similar to Neptune. In fact, this kind of cognition is not reliable. Neptune is not in the habitable zone, it is just a planet on the edge of the solar system. If in the early days of the solar system, Neptune was in the habitable zone, then the fate of the future will be completely different from that of the present. It is possible that Neptune will become the second earth.
So, 125 light-years away, this planet has some similarities with Neptune, and its fate may be totally different from Neptune. Neptune in the solar system is a world of ice, and this “Neptune” in the habitable zone may be a beautiful ocean world. Roughly speaking, the probability that water exists in the atmosphere of this planet is very high.
The existence of water vapor in the atmosphere basically means the existence of water cycle, and the probability of large amount of liquid water on the surface is very high. Therefore, the probability of life on k2-18b is very high, which is naturally good news for scientists. To be able to find life planets outside the solar system is quite different from that in the solar system.
Even if we can find extraterrestrial life in the solar system in the future, it can only be some relatively simple primitive life at most. Because the earth is the only beautiful ecological planet in the habitable zone of the solar system. Outside the solar system, we can find many beautiful earth like planets which are obviously different from other gray planets through telescopes.
If this kind of earth like planet is in the habitable zone, it will probably be a beautiful ecological planet, and the probability of life in the ecological galaxy is very high. Moreover, only the ecological planet can make primitive life evolve continuously, and finally evolve into advanced life or even intelligent life.
Of course, it is not easy for us to make sure that there is life on the exoplanets. First of all, we need to have the speed to get out of the solar system, and this speed should at least reach the speed of sub light. To achieve this speed, we need a major breakthrough in energy. Maybe only after the realization of controllable nuclear fusion can we have the ability to go out of the solar system and explore other nearby galaxies.