July 20 is human moon day. The moon is the closest object to us, and it leaves human footprints on the surface of the moon. From the beginning of looking up at the moon, it has been studied continuously, and many of the characteristics of the moon have been in our grasp. However, this “near neighbor” still remains a lot of mystery, we have to explore. How was the moon born? Its age geometry? Why did the moon’s magnetic field disappear? Why is the distance of the earth and moon gradually getting farther?
The study of these problems will not only help us understand the moon itself, but also explore more mysteries of the universe.
The three mysteries are interesting.
Where does the moon come from? Ping Jinsong, a researcher at the National Observatory of the Chinese Academy of Sciences and the chief expert of the Low Frequency Radio Explorer of the Chang’e-4, said there are four main hypotheses about the origin of the moon, namely, the division, homologous, capture and the origin of the big impact. “These four hypotheses still have many disadvantages that are difficult to justify in terms of differences in the composition of the Earth and moons and the rotation speed, and the similarity of oxygen and other isotope compositions.” He said.
Among them, the big impact origin hypothesis faces relatively few questions. That’s because in the 1960s, the Moon Rocks brought back by the Apollo program and the Soviet Moon Program contained almost exactly the same proportion of oxygen isotopes as the Earth’s mantle. And scientists found that lunar rock samples contained virtually non-volatile and light elements. The researchers believe this is because the extreme heat generated by the impact gasifies these elements to cause them to escape. “However, the collision and reconvergence of two completely distinct solid planets does not explain why there are significantly undistinguishable and 5.3 billion-year-old rocks on the lunar surface or samples.” Mr Ping said none of the hypotheses was complete.
Another fascinating mystery is the moon’s magnetic field. Analysis of the moon’s rocks proves that the moon once had a strong magnetic field. According to previous judgment, there is iron-nickel or iron sulfide nickel core inside the moon, and early evolution produces generator mechanisms to form an overall magnetic field.
Some researchers believe that the moon’s first generator effect may have produced a powerful magnetic field 4 billion years ago. Past decades of exploration have found that the average magnetic field strength of the entire lunar surface today is less than 0.2 micro-Teslas, suggesting that the current moon either does not have a globally distributed magnetic field or has only one extremely weak global magnetic field. Some researchers also believe that about 1 billion years ago, the moon’s internal engine, the moon’s core crystal, stopped working, causing the moon’s magnetic field to gradually disappear and rapidly drop to 0.1 micro-Tesla. So when exactly did the moon’s magnetic field come birth? Why is it almost gone now? These remain unsolved mysteries.
Is the moon far from the earth? This is another inexplicable mystery of the moon. The moon’s average distance from Earth is about 380,000 kilometers, and it is observed that the moon is moving away from Earth at a rate of about 3.8 centimeters per year. Since 1970, the average distance between the earth and month has increased by about 1.9 metres.
In this regard, it is explained that the moon around the earth rotation of the angle speed is slower than the earth’s rotation, coupled with the gravitational action of the sun, the earth and the moon on the gravitational distribution imbalance and time changes, which in turn triggered solid tidal phenomenon, resulting in the Earth’s rotation speed slower and the moon rotation speed up. In addition, the energy and angular momentum of the Earth-moon system are conserved, resulting in the Earth’s rotation speed decreased and the angular momentum and capacity transferred to the moon, in which part of the increase in the rotation of the moon into potential energy, so that the moon gradually away from the Earth.
The disclosure also requires the upgrading of detection technology.
How to solve the above mystery?
Ping Jinsong believes that from the detection technology, it is necessary to set up a new type of long-term working lunar seismometer, laser and microwave ranging equipment between the moon, deep into the lunar surface can penetrate the lunar soil, high sensitivity magnetometer and so on.
“Similar to earth monitoring, the above-mentioned equipment should be networked in multiple parts of the lunar surface for overall monitoring; Ping Said the new techniques could provide a basis for revision or reconstruction of existing theories and hypotheses by obtaining high-precision measurements of lunar tremors, the moon’s long-wavelength gravity and magnetic field, as well as the movement and rotation of the moon’s orbit.
Ping Said the deployment of the above observation technology will help to obtain detailed information on the structure of the deep part of the moon, such as the nickel content of the moon core iron, whether the core is present, how big, whether it is fully crystal solid state, whether the outer core and the outer core are coupled with the lunar boundary zone, the internal thermal energy and its source, and the global magnetic field background state. Then based on this information, the moon core crystallization age and magnetic field disappearance, based on the state of the core matter, the total amount of the moon formation mechanism, and the fine grasp of the moon away from the Earth’s condition and production mechanism.
“Uncovering the mystery of the origin of the moon is of great significance for the study and discovery of the formation and evolution of the two planets of exoplanet systems, especially the two solid planets with livable zones, and the explanation of the mystery of the disappearance of the lunar magnetic field will help to understand the evolution of other Earth-like planets without the rapid disappearance of the magnetic field of the solar system, and the general phenomenon of the rapid disappearance of the magnetic field of the solar system is the norm of planetary evolution, and the Earth is an extreme exception.” In addition, the search for exoplanets may well require the need to increase the inherent magnetic field as a strong constraint. Ping Jinsong stressed.
At present, the moon’s distance from the Earth is very slow and will not have a significant negative impact on the evolution of the Earth-moon system and the existence of human society. However, accurate measurementanding and grasping the distance speed of the moon can be used as a high-precision measurement reference for human social activity and even to support the detection of gravitational waves in ultra-low frequency space.