What other planets are there for humans to live on?

Category: Education/Science

Analysis:

The mystery of life in the universe

In ancient times, science was underdeveloped, and people have been yearning for "Heaven on earth" and "heaven". As a result, there are many stories: Chang'e flying to the moon, fairies descending to earth, the Jade Emperor, the Queen Mother... Now that science has developed, people know that those are all myths made up by the ancients. However, whether there is life in space beyond the earth is still a very fascinating question.

Theoretically, the universe is infinite. The Earth is only a planet in the solar system, and the solar system is only a very small part of the Milky Way. There are approximately 150 billion stars in the entire Milky Way, and there are many planetary systems similar to the solar system, among which planets similar to the Earth must exist. It can be guessed that the earth is by no means the only celestial body with life. However, humans have not yet found another planet with life.

Which celestial bodies may have life? What conditions must this celestial body meet? After we understand the process of the origin of life, we believe that there should be at least the following conditions: first, the temperature suitable for biological survival, which should generally be between -50°C and +50°C; second, necessary water, life substances The activities of proteins, nucleic acids and enzymes are closely related to water. Without water, there would be no life. The third is the atmosphere with appropriate composition. Although a few anaerobic bacteria have been found to survive without oxygen, oxygen and Carbon dioxide is extremely important for the existence of life; fourth, there must be enough light and heat to provide energy for life systems.

Based on these conditions, scientists first analyzed other planets in the solar system except the earth: Mercury is the closest to the sun, and its surface temperature can reach 300 to 400°C when facing the sun, making it impossible for life to exist; Venus is A planet with high temperature, lack of oxygen, water, and strong sunlight radiation cannot have life; Jupiter, Saturn, Uranus, Neptune and Pluto are far away from the sun, and their surface temperatures are low, generally at -140°C. Below C, the atmosphere surrounding them is mainly composed of hydrogen, followed by methane and ammonia. Therefore, life cannot exist on these planets.

The only planet in the solar system that may have life is Mars. The question of whether there is life on Mars has been debated for more than 100 years. With the rapid development of aerospace technology, this mystery has now been solved.

Mars and the Earth have many similarities: the Earth's rotation takes 23 hours and 56 minutes, and Mars' rotation takes 24 hours and 37 minutes; the Earth's rotation axis has an inclination of 23 degrees and 27 minutes with the orbital plane. , and the inclination of Mars is 24 degrees, so Mars has day and night and four seasons like the Earth. The poles of Mars are also frozen by ice and snow like the Earth. What's more interesting is that in 1879, an Italian astronomer observed many vertical and horizontal black lines on the surface of Mars. People speculated that these were canals dug by Martians. People have also observed that the color of the surface of Mars changes with the seasons. Some people think that this is the color of the plants on the surface of Mars changing with the seasons.

Due to the rapid development of space technology, scientists decided to use spacecraft to conduct close observations of Mars in order to uncover the mystery of Mars. In 1971, the Mariner 9 spacecraft launched by the United States entered an orbit around Mars and took a large number of photos of Mars. These photos show that the so-called "canals" observed by Italian astronomers turned out to be a series of dark craters and dark spots. Through close observation, it was also discovered that the so-called seasonal changes in color on the surface of Mars that were previously observed were not caused by the growth and withering of plants, but by the wind blowing dust on the surface of Mars. Changes in color lightness and darkness.

The spacecraft also discovered that Mars is a very dry planet. Although water vapor is found in its atmosphere, the content is very small, only one percent of that in desert areas on Earth; Mars’ atmosphere is very Thin, 96% is carbon dioxide and very little oxygen; the surface temperature of Mars is very low; there is no magnetic field on Mars, and there is no ozone layer in its atmosphere, so it cannot withstand ultraviolet rays and various cosmic rays. All these factors All show that it is difficult for life to survive on Mars.

In order to further investigate Mars, in 1976, the United States launched two more spacecraft called "Vikings". The two spacecraft landed on the surface of Mars and conducted a series of analyzes and tests. Among them, there were two important results. One was that no organic molecules were detected in the soil of Mars, and the other was that in the culture of samples taken from the surface of Mars, No presence of microorganisms was found. These two results directly prove that there is no life on the surface of Mars in the area where the spacecraft landed. At this time, some scientists asked whether living substances would exist in the rock formations of Mars? This remains to be further studied.

People have not yet been able to find life in space beyond the earth, but scientists still believe that life exists there. In recent years, through analysis of some meteorites that fell on the earth, it was discovered that there are organic molecules in outer space.

In 1976, there was a meteorite rain in Jilin Province in Northeast my country. After sampling and analyzing the largest meteorite block, organic molecules were also found.

Whether there is life beyond the earth is a mystery of life in the universe that humans have been exploring.

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