The text "The Mystery of Life in the Universe" introduces the difficult process of scientists exploring whether there is life beyond the earth. Next, share the central idea of ??the mystery of life in the universe, the original text of the text, and the general idea of ??the paragraph.
Central Idea of ??the Mystery of Life in the Universe
The text "The Mystery of Life in the Universe" introduces the difficult process of scientists exploring whether there is life outside the earth. It explains that so far, the earth has Whether there is life outside remains an unsolved mystery. It expresses the author's admiration for scientists' pursuit of true knowledge and continuous exploration, and at the same time stimulates students' interest in loving science, learning science, and exploring the mysteries of the universe. Original text on The Mystery of Life in the Universe
In ancient times, when science was underdeveloped, people always yearned for the "world in the sky." As a result, there are many stories: Chang'e flying to the moon, fairies descending to earth, the peach festival... Now, with the development of science, people know that these are all myths made up by the ancients. However, whether there is life in space beyond the earth is still a fascinating question.
Theoretically, the universe is infinite. The earth is just a planet in the solar system, and the solar system is only a very small part of the Milky Way, and the Milky Way is just a drop in the ocean of the universe. There are hundreds of billions of stars in the entire Milky Way, and there are many celestial systems similar to the solar system, among which there must be planets similar to the Earth. 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 have? After understanding the process of the origin of life, people believe that there should be at least the following conditions: First, it is suitable for biological survival The temperature should generally be between minus 50 degrees Celsius and plus 150 degrees Celsius; secondly, necessary water. The vitality of living substances such as proteins and nucleic acids is closely related to water. Without water, there will be no life; thirdly, It is an atmosphere with appropriate composition. Although a few anaerobic bacteria have been found to survive without oxygen, oxygen and carbon dioxide are extremely important for the existence of life; fourth, there must be enough light and heat to provide energy for the living system. .
Based on these conditions, scientists first analyzed other planets in the solar system except the earth. Mercury is closest to the sun, and its surface temperature reaches 300 to 400 degrees Celsius when facing the sun, making it impossible for life to exist. Venus is a planet lacking oxygen and water, with thick clouds. The "greenhouse effect" caused by sunlight radiation and clouds makes the surface temperature of Venus extremely high, making it impossible for life to exist. Jupiter, Saturn, Uranus and Neptune are far away from the sun, and their surface temperatures are generally below minus 140 degrees Celsius. Therefore, life cannot exist.
The only planet in the solar system that may still have life is Mars. Mars and the Earth have many similarities: one rotation of the Earth takes 23 hours, 56 minutes and 4 seconds, and one rotation of Mars takes 24 hours and 37 minutes; the Earth's rotation axis has an inclination angle of 66 degrees and 34 minutes with the plane of its orbit, while Mars takes 24 hours and 37 minutes to rotate once. The inclination angle is about 66 degrees and 1 minute, so the length of day and night on Mars and Earth are similar, and there are also four seasons. What’s more interesting is that in 1877, 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.
In order to uncover the mystery of Mars, scientists decided to use a spacecraft to conduct close observations 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 around, causing the color. Changes in light and dark.
Scientists 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 It is thin, with 96% carbon dioxide and very little oxygen content; 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 resist ultraviolet rays and various cosmic rays. All these factors make it difficult for life to exist on Mars.
In order to further investigate Mars, in 1975, the United States launched two spacecraft named "Viking". The two spacecraft landed on Mars and conducted a series of analyzes and tests, and obtained two important results. First, no organic molecules were detected in the soil of Mars; second, no microorganisms were found in the culture of samples taken from the Martian surface. existence. This proves that there is no life on the surface of Mars in the area where the spacecraft landed. Scientists also asked whether living materials would exist in the rock formations of Mars? This needs further study.
People have not yet found life in space beyond the earth, but they still believe that life exists in distant space.
In recent years, scientists have analyzed some meteorites that fell on the earth and found that there are organic molecules on the meteorites, indicating that there may be life in space.
Whether there is life outside the earth is a mystery of the universe that humans have been exploring. The main idea of ??the paragraph on the mystery of life in the universe
Part one (paragraphs 1-2): Is there life in space beyond the earth?
Part 2 (paragraphs 3-4): Conditions for the existence of life on celestial bodies, scientists’ detection of planets in the solar system.
Part 3 (paragraphs 5-8): Exploration and investigation of Mars.
Part 4 (paragraphs 9-10): Whether there is life in space still needs to be explored by humans.