Half a century ago, with the rapid development of human industry, we finally realized our dream of flying out of the earth. After human beings walked out of the earth, the exploration of extraterrestrial life became a very important research and exploration project for mankind. From the perspective of the vast universe, theoretically, it is impossible to have only the planet of life, the earth.
The existence of extraterrestrial life should be a high-probability event, but before we actually discover extraterrestrial life, all kinds of questions about extraterrestrial life are just conjectures. In order to turn this conjecture into reality, scientists have begun a large number of observational studies, hoping to discover a second living planet.
Since we basically know nothing about extraterrestrial life, when we explore and find extraterrestrial life, we basically use the earth as a blueprint and a reference to search for. The fact that the earth can become a planet of life rich in species shows that the earth must have various natural advantages and the various conditions required for the birth of life.
Scientists divide these conditions into internal and external factors. The internal factors are 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. Wait. The main external condition is that the distance between the earth and the sun is very suitable, that is, it is in a habitable zone.
Only planets in the habitable zone can have a large amount of liquid water on the surface, and water is the source of life. If there is no liquid water on the surface of the earth, it is possible that early life cannot be born and cannot become a living planet. In addition to the Earth, there are also Venus and Mars in the habitable zone of the solar system. However, the environment on the surfaces of these two planets is very harsh.
The atmosphere of Venus is mainly composed of carbon dioxide, and the greenhouse effect is particularly serious, so the surface temperature is as high as 460 degrees Celsius. Such a high temperature is naturally impossible to have a large amount of liquid water, and because Mars is at the edge of the habitable zone, the temperature is low, the atmosphere is very thin, and the surface is basically a desert. Only a small amount of ice water exists at the 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 have focused on exploring life outside the solar system. We must know that the solar system is only one of the hundreds of billions of stars in the Milky Way, and every star system has a habitable zone, and there may be several terrestrial planets. These terrestrial planets in the habitable zone, as long as the conditions are right, the probability of liquid water on the surface is very high, and with water, life can be born.
Through the continuous improvement of scientists’ knowledge 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 star system, like the solar system, there are many planets with water. However, the surface of the planet outside the habitable zone can only exist in the form of ice. Only the planetary surface in the habitable zone is likely to have a large amount of liquid water.
Scientists look for planets that may have a lot of liquid water outside the solar system. The first goal is to find the habitable zone of stars. Some terrestrial planets that are very similar to the Earth are undoubtedly more likely to have life. The discovery of one of the exoplanets once again gave mankind hope. This exoplanet is named K2-18b.
K2-18b is 124 light-years away from the Earth, with a radius and mass of 2.6 times and 8.6 times that of the Earth, and is located in the habitable zone of its star. Last year, a scientific team detected water vapor in the atmosphere of K2-18b, which caused a sensation in the astronomy community. But scientists did not know the thickness of K2-18b’s atmosphere and the internal conditions 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 the 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 great to make life impossible. survive.
Of course, this is only the preliminary research results of scientists. Because this exoplanet is far away from us, it is difficult for us to truly understand its atmospheric structure through some observational data, let alone accurately understand its surface conditions. Therefore, we can only speculate about some of its conditions. No matter what, it can be different from the others, and it is obviously different from other terrestrial planets. Then such a planet is worthy of our attention.
Some scientists think that it is similar to Neptune. In fact, this perception is not reliable. You must know that Neptune is not in a habitable zone, it is just a planet on the edge of the solar system. If Neptune was in the habitable zone in the early solar system, then the fate of the future will be completely different from the present, and it is possible that Neptune will become the second earth.
Therefore, this planet 125 light-years away has some similarities with Neptune, and its fate may be completely different from that of Neptune. Neptune in the solar system is an ice world, and this “Neptune” in the habitable zone may be a beautiful ocean world. In terms of high probability, we can determine that the probability of the presence of water in the atmosphere of this planet is very high through the observed images.
The presence of water vapor in the atmosphere basically means that there is a water cycle, and the probability of a large amount of liquid water on the surface is very high. Therefore, the probability of the existence of life on planet K2-18b is very high, which is naturally good news for scientists. It is necessary to know that the discovery of life on planets outside the solar system and the discovery of extraterrestrial life in the solar system have completely different meanings.
Even if we can discover extraterrestrial life in the solar system in the future, it can only be simple primitive life at best. Because the habitable zone of the solar system has only the beautiful ecological planet Earth, and outside the solar system, we can discover many beautiful terrestrial planets through astronomical telescopes, which are obviously different from other gray planets.
If this kind of terrestrial planet is in the habitable zone, it will most likely be a beautiful ecological planet, and the probability of life in an ecological galaxy is naturally very high. And only the ecological planet can allow primitive life to evolve and eventually evolve into advanced life or even intelligent life.
Of course, it is not easy for us to truly determine the existence of life on exoplanets. First of all, we must have the speed that can get out of the solar system, and this speed must reach at least the sub-light speed. To achieve this speed, we need a major breakthrough in energy. Perhaps we will only have it after achieving controllable nuclear fusion. Ability to initially get out of the solar system and explore other nearby galaxies.