1 Whether at school or in society, the most unfamiliar thing for everyone is
2. In ancient times, the ancients often daydreamed about the world in the sky, so there were many fairy tales, such as "the Goddess Chang'e flying to the moon", "Fairy Descent" and "Flat Peach Festival".
But now that science is developed and detection instruments are advanced, it is obvious that those stories have long been imagined and fabricated. But is there life outside the earth? This is still an unsolved mystery.
According to statistics, the planet that is most likely to have life at present is Mars, because the time and inclination of its rotation in one day are very similar to that of the Earth, so the first goal of mankind is to land on Mars.
5. 197 1 year, the United States launched the "Mariner I" spacecraft and took many photos of Mars, but the results denied people's previous speculation.
6. Later, scientists found that Mars is very dry, with water vapor content less than 1% of the desert area of the earth and oxygen content less than 5% of the atmosphere. More importantly, Mars has no ozone layer and cannot resist ultraviolet radiation at all.
All these data show that there will be no life on the surface of Mars. In this harsh environment, there will be no life, even microorganisms, except in or under rocks for a century.
In recent years, scientists have discovered organic molecules on meteorites, which proves that there may be signs of microbial life in the depths of the universe. In view of this phenomenon, we can judge the general orientation of organic molecules from the source and trajectory of meteorites, and look for life from the other end of the universe along that direction.
9. Whether there is life outside the earth is a big puzzle for human exploration. We need to keep exploring, even if it takes a lifetime of efforts. ...
10. Ancient science was underdeveloped, and people always yearned for "heaven and earth" and "heaven". So there are many stories: the Goddess Chang'e flying to the moon, Fairy Descending from Earth, Jade Emperor, Tianmu ... Now with the development of science, people know that they are all myths fabricated by the ancients.
1 1. Theoretically, the universe is infinite. The earth is just a planet in the solar system, and the solar system is only a tiny part of the Milky Way.
12, there are hundreds of billions of stars in the whole galaxy, and there are many planetary systems similar to the solar system, among which there must be planets similar to the earth.
13, which celestial bodies may have life? What conditions must this celestial body have? After understanding the process of the origin of life, people think that at least the following conditions should be met: First, the temperature suitable for living organisms should generally be between MINUS 50 degrees and above zero 150 degrees Celsius.
14, and the second is essential water. The vitality of protein, nucleic acids, enzymes and other living substances is closely related to water. Without water, there is no life.
15, and the third is the right atmosphere for composition. Although it has been found that a few anaerobic bacteria can survive without oxygen, oxygen and carbon dioxide are extremely important for the existence of life; Fourth, there should be enough light and heat to provide energy for the living system.