Shapers of Earth's history: Are meteorites "destroyers" or "midwives"?

Tuchong Creative

In the long history of the Earth, meteorites, as messengers from the universe, not only provide us with clues to explore the depths of the universe, but also play an important role in the evolution of the Earth. These extraterrestrial visitors, carrying the original materials from the early formation of the solar system, traveled through the vast space and eventually fell on the surface of the Earth. Today, I will take you to learn more about the origin and classification of meteorites, as well as how scientists uncover their mysteries and explore the impact and shaping of these cosmic fragments on the history of the Earth.

The impact and significance of meteorites on Earth's history

Meteorites have had many impacts on the Earth. First, they brought water and organic matter to the Earth, which may be one of the key factors in the origin of life. Scientists speculate that part of the water in the Earth's early atmosphere and oceans may have come from meteorites. In addition, organic compounds in meteorites, such as amino acids, are considered potential seeds for the origin of life on Earth.

Secondly, the huge energy released when meteorites hit the earth has a profound impact on the earth's geological structure and surface morphology. These impact events may cause the uplift and fracture of the earth's crust, form mountains and basins, and even affect the earth's magnetic field. At the same time, large-scale impact events may also trigger global climate change, such as ice ages. For example, the Chicxulub impact event about 66 million years ago is believed to be related to the extinction of dinosaurs.

In addition, meteorite impacts also have a significant impact on biodiversity. On the one hand, large-scale impact events may lead to mass extinction, such as the disappearance of dinosaurs; on the other hand, environmental changes after the impact may also give rise to new species and promote the evolution of biodiversity.

The difficulty of classifying and confirming the origin of meteorites that hit the Earth

Meteorites are classified into different types based on their composition and structure. The most common are ordinary chondrites, which account for about 80% of all collected meteorites. These meteorites are usually composed of rock and metal particles, containing primitive materials from the early formation of the solar system. Scientists divide these meteorites into three types based on the different iron and metal content, H, L and LL, corresponding to high iron, low iron and low iron and low metal types. Among the meteorite samples collected on Earth, H and L types are the main ones.

The second largest group of meteorites are iron meteorites, which are mainly composed of iron and nickel and account for about 5% of all meteorites. Stony-iron meteorites contain both rock and metal components and are relatively rare.

The difficulty in confirming the origin of meteorites lies in the huge number of asteroids in space and their orbits are complex and changeable. Most meteorites change due to high temperature combustion when passing through the Earth's atmosphere, which makes it extremely difficult to determine their original source. Currently, scientists can only clearly identify the source of about 6% of meteorites. To solve this problem, scientists have used a variety of methods, including spectral analysis, radioactive isotope dating and computer simulation.

How do scientists reveal the mystery of the origin of meteorites?

The latest scientific research results published in Nature reveal clues to the origin of meteorites. Through chemical analysis of chondrites, scientists found that L-type chondrites on Earth may come from a family of asteroids called the "Queen Family". These asteroids shattered in a violent impact about 450 million years ago, forming a large number of fragments, some of which eventually fell to Earth.

In another study, scientists used computer simulations to find that the H-type and L-type chondrites currently flowing into the Earth may have originated from three recent asteroid breakup events. These events occurred about 5.8 million years ago, 7.6 million years ago, and 40 million years ago, and the asteroids involved were all larger than 30 kilometers in diameter. The fragments produced by these breakup events eventually became meteorites on Earth through complex orbital evolution.

These discoveries benefited from scientists' in-depth research on the asteroid belt. By analyzing the spectral data of asteroids, scientists were able to link meteorites on Earth to specific asteroid families. For example, scientists from the European Southern Observatory (ESO) used the Very Large Telescope to collect spectral data of asteroids in the main asteroid belt between Mars and Jupiter, and found a group of asteroids called the Queen Family, whose spectral characteristics are very close to those of L-type chondrites on Earth.

What is the significance of this achievement?

This discovery not only helps us better understand the origin of meteorites, but also provides a new perspective for studying Earth's history. By analyzing the composition of meteorites, we can trace the changes in Earth's atmosphere and climate, and even explore the origin of life. In addition, understanding the origin of meteorites is also important for predicting and preventing potential celestial impact risks.

The study of meteorites also helps us understand the formation and evolution of the solar system. As witnesses of the early history of the solar system, meteorites record the physical and chemical conditions in the early stages of the formation of the solar system. By studying meteorites, we can better understand the formation process of planets and the distribution and evolution of matter in the solar system.

In addition, the study of meteorites also has potential value for future space exploration and resource utilization. With the development of space technology, asteroid mining and resource utilization are gradually becoming possible. The study of meteorites can provide us with important information about the composition and structure of asteroids, and provide a scientific basis for future space resource development.

In short, meteorites, as a bridge connecting the earth and the universe, not only enrich our understanding of the universe, but also leave a deep mark in the history of the earth. With the advancement of science and technology, we are expected to uncover more secrets about these extraterrestrial visitors and add a new chapter to the journey of human exploration of the universe.

This article is a work supported by the Science Popularization China Creation Cultivation Program

Author: Xiao Long

Reviewer: Zhou Binghong, Researcher, Ambassador of China Aerospace Science Popularization

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.