Looking for alien habitats

Lai's vast world can always arouse people's rich fantasies. Over the years, people have made up countless beautiful and moving stories, imagining that there will be a "fairyland on earth" nine days away, which can make people get rid of human suffering and misfortune. Among them, the moon is the most talked about theme. Indians saw a man working on the moon, Indians saw a rabbit running on the moon, Samoans saw a woman spinning, and China saw a charming girl, Chang 'e, running to the moon because she stole the fairy medicine ... Until now, people are still passing these beautiful stories on from generation to generation.

With the development of science and technology, we now know that there are countless celestial bodies like the earth in the universe, and the earth can only be counted as a drop in the ocean. . So, is there life on other celestial bodies besides the earth? Can humans leave the small earth to seek a broader living space on other planets? With the gradual increase of human beings on the earth and the gradual deterioration of the ecological environment, people are increasingly hoping to find their neighbors on other planets and are eager to find oases outside the sky in order to find another habitat in times of crisis. 2 1, 65438, in July 1969, man landed on the moon for the first time, and then scientific probes landed on Venus and Mars, the two closest planets to the earth, on 19751October 22 and1July 20, 976 respectively. The distant dream of the ancients came true, which really excited mankind, but when people calmed down from the high excitement, they were surprised to find that there was neither their own kind nor a place to live.

Take the moon as an example, nearly 20 astronauts have landed on the moon, and the cumulative stay time on the moon has exceeded 600 hours. The results completely confirmed the conclusion made by astronomers: the moon is a silent planet without air and water, covered with barren sand and never had life; If there is no special spacesuit protection, any creature from the earth will suffocate immediately.

The results of the exploration of Venus are even more daunting. The atmosphere on the surface of Venus is too dense, which is 100 times higher than that on the earth, and almost all of it is carbon dioxide. The temperature is around 500℃ day and night, and life on earth will turn to ashes immediately if it is put inside. On the other hand, the atmospheric pressure on the surface of Mars is too low, which is equivalent to the atmospheric density at an altitude of more than 30 kilometers on the surface of the earth. The main component is carbon dioxide. The temperature is often as low as-130℃, and nothing alive has been found yet. People's test results of mercury are equally disappointing. Sailor 1974 and Sailor 10 passed Mercury three times and found it as desolate and dead as the moon, with no air. The temperature at night is-160℃, and the temperature during the day is 300℃. Naturally, there will be no life forms.

As far as life on earth is concerned, although there are various species and forms, they are all composed of hydrocarbons: life exists in the form of protein, but it is based on nucleic acid. Therefore, when scientists explore whether there is life on other planets, the premise is whether there are hydrocarbons. If hydrocarbons are found on a planet, there is at least information similar to life on earth. In addition, suitable temperature, necessary moisture, suitable air pressure, sufficient sunshine and a certain proportion of various elements are necessary conditions for the survival and development of organisms. If any celestial body in the universe has these conditions, there is the possibility of life. In recent years, the detection results of several planets in the solar system, such as Jupiter, Saturn, Uranus, Neptune and Pluto, which are far away from the earth and the sun, show that they are not only large in mass, low in density and fast in rotation, but also mainly composed of hydrogen (followed by methane and ammonia), and their surface temperatures are below-140℃. Under such conditions, life naturally cannot survive.

It seems that life on earth is a lonely traveler in the solar system. So is there life in other galaxies in the universe?

In recent years, many scientific investigations have confirmed that hydrocarbons are ubiquitous in the universe. Scientists believe that hydrocarbons are the products of chemical action during the development of the universe. Once the appropriate conditions are met, it is entirely possible for these organic molecules to evolve into life. Millions of years ago, the appearance of human beings on the earth was not an isolated event in the infinite universe. There are more than 654.38+000 billion sun-like stars in our Milky Way alone, and each star may have its own planet, so there should be "others" in the universe. But the youngest "sun" that astronomers can find recently-proxima centauri Centauri (China's name is Nanmen Erc) is also 4.2 light years away, about 4 billion kilometers. It takes more than four years for light to arrive, which is really beyond the reach of human beings.

So far, no intelligent life has been found within 4 billion kilometers from the earth. The earth on which human beings live is like a lonely boat, with no neighbors to call and no natural base to dock. But this does not prevent us from exerting the unique imagination of human beings-in the vast universe, some planets may be in the pre-life development stage, some may be in the primary stage of life, and some may already have a more civilized, advanced and better society than the earth! These are all to be answered by future scientific facts.