What was the sun like a long time ago? What has to be told in the Milky Way? If you want to know these secrets, come to the moon and read its “diary”.
How to write a “diary” on the moon
Using methods such as stratum coverage, statistical analysis of impact crater density, and moon rock isotope dating, scientists have speculated that the Moon is approximately 4.4 billion to 4.6 billion years old. In such a long time, the moon is exposed to the space environment day and night, receiving high-energy particle radiation from the sun and other stars in the Milky Way for many years. These particles “burned” the moon and reacted with other materials on the moon’s surface. This is the “cosmic diary” recorded by the moon.
You might say that these diaries also have records on the earth. Why don’t we look for “cosmic diaries” on the earth? The solar wind (the high-energy particles emitted by the sun) will blow through the entire solar system, but these high-energy charged particles rarely reach the surface of the earth. This is because there is a magnetosphere covering the earth, which will change the path of these charged particles and make the particles turn before they collide with the earth. The colorful aurora that appears at the two poles of the earth is the interaction between the earth’s magnetic field and the solar wind. At the same time, the earth also has a thick atmosphere, which also absorbs these particles. Therefore, high-energy particles can hardly meet the surface of the earth, so there is no need to record a “diary”.
But the moon is different. Although there may have been a magnetic field in the short period when it was just formed, the existence of the moon’s magnetic field is basically undetectable now. Moreover, the moon has almost no atmosphere, so the solar wind can directly reach the surface of the moon. After each small solar particle collides with moondust, it will tear a tiny hole in the moondust, and even change the elemental composition of the moondust. Therefore, by studying the chemical structure of moon dust, we can see a record of solar activity.
In addition to the sun, other stellar activities in the Milky Way also emit high-energy particles, such as supernova explosions that occur when huge stars die. The particles released by these activities usually have more energy than the solar wind, so that they can leave “obvious” scars on the moon rock, which can be observed under a microscope. At the same time, cosmic rays can also change the molecular composition of barite, causing it to undergo nuclear fission. Reading “Moon Diary”, we can learn more about the secret history of the universe.
The Chronicle of the Sun in the Diary
Since 1969, the US Apollo has planned to land on the moon six times, and the Soviet Union Lunar 1 landed on the moon three times. A total of more than 380 kilograms of moon rock, pebbles and lunar soil have been retrieved and extensive lunar geological research has been carried out. In December 2020, China’s Chang’e 5 spacecraft collected more than 1,731 grams of lunar samples. From these “diaries”, how many stories did scientists read?
Eight planets have been discovered in the solar system. Among them, Mars has a geological environment similar to that of the earth. The thick atmosphere of Venus has some conditions suitable for living creatures. However, no trace of life activity has been found on these planets, but the earth has It is full of life. Why is this?
The answer to this question is recorded in the “diary” of the moon. The team led by NASA’s astrophysicist Praba Sassina inspected the rock samples brought back from the moon and found that lunar rocks have different chemical compositions than those on the earth. The potassium and sodium in the moon rocks The content of other elements is significantly less. Scientists believe that this is because the solar wind strips these chemicals from the surface of the moon, and the earth’s atmosphere weakens the influence of the solar wind.
The same thing happened in the “infancy” of the sun. 4 billion years ago, when the sun was a baby, it experienced a strong burst of radiation, ejecting hot, energetic particles outward. These high-energy particles came to the earth and stimulated the germination of life on the earth by triggering chemical reactions, and since then life appeared on the earth. However, the same solar wind blew away the atmosphere of other planets and robbed the planet itself of nutrients, preventing life on other planets from appearing. The reason for this difference is that planets such as Mars and Venus have weak magnetic fields and the atmosphere is more easily destroyed by the solar wind. The earth has a magnetic field protection. The solar wind not only does not damage the earth’s atmosphere, but promotes the birth of life.
Milky Way Events Recorded on the Moon
In the past 9 million years, about 300 light-years away from the earth, there have been many supernova explosions. These events not only changed the earth’s climate, but also caused small-scale biological extinctions. These stories are recently read by scientists from the lunar soil.
In the past, scientists believed that only a supernova explosion that occurred within 25 light-years of the earth could cause the earth to receive strong enough radiation to cause mass extinction, while supernova explosions hundreds of light-years away were not enough. Fear, but the evidence that has been discovered in recent years has changed this thinking. A research team from Washburn University in the United States observed the explosion of a supernova about 325 light-years away from the earth, and found that the energy of high-energy particles radiated by it was stronger than the solar wind, and could travel hundreds of light-years to reach the earth. Pass through the earth’s magnetic field and affect the life of the earth.
A research team once detected a large amount of iron-60 from the earth’s deep-sea sediment samples. After analysis, the age of these materials is about 2 to 8 million years. The research team speculates that these iron-60s fell to the earth after supernova explosions. Up. In 2016, the team also detected iron-60 in lunar soil samples, and the age of these iron-60s was the same as that in the earth’s deep-sea sediments. In addition, in the lunar soil samples, the researchers also found elements such as calcium-41 and manganese-53, which indicate the timing of the same supernova explosion.
In the end, the research team calculated that a supernova explosion occurred approximately 300 light-years from Earth approximately 2.6 million years ago. The particles produced by this explosion affected the earth’s clouds, thereby making the earth cold, and also extinction of some small groups of species on the earth, and caused some genetic mutations in the organisms, which may trigger a species diversity. evolution.
The moon can provide more information about the universe. Scientists once put forward the idea to find evidence of dark matter in ancient rocks: When dark matter passes through rock particles, they leave traces of damage in certain minerals. In order to reduce the influence of geological and human activities, they searched for ancient rocks deep in the earth, but the excavation work is dangerous, and it takes a lot of time to prove that the traces left in the rocks are not affected by neutrons, solar neutrinos or other substances. The impact is only caused by dark matter. It may be a better choice to use moon rock to find dark matter. It is old enough to have been hit by dark matter many times; and on the moon, it is almost unaffected by geological and human activities, and there are traces of dark matter. (If there is any) easier to keep for a long time.
There are still many unsolved mysteries in the universe, and the “diary” of the moon is likely to help us solve some of the major mysteries. Marching into the moon is in the ascendant.