How was our solar system formed
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Formation of Our Solar System
Introduction to Solar System Formation
The formation of our solar system began approximately 4.56 billion years ago. Despite the vast time span since its inception, several clues about its formation remain, derived from meteorites, the current structure of the solar system, and observations of planet-forming systems around young stars . These clues help us understand the stages of planet formation, the lifetime of the solar protoplanetary disc, and the solar system's potential formation within a star cluster .
Collapse of Interstellar Cloud
The widely accepted theory is that the solar system formed from the gravitational collapse of an interstellar cloud of gas and dust. This collapse led to the formation of a rotating, dusty disc around the newly formed Sun . The material in this disc gradually accreted into small planetary bodies known as planetesimals, which served as the building blocks for planets .
Role of Meteorites and Radionuclides
Meteorites provide significant insights into the early solar system. The presence of short-lived radionuclides such as 60Fe, 26Al, and 41Ca in meteorites suggests that a nearby supernova occurred shortly before the solar system's formation, indicating that the Sun formed in a massive star-forming region . This supernova likely triggered the collapse of the interstellar cloud and injected these radionuclides into the nascent solar system 37.
Formation of Planetesimals and Planets
The solar system's formation involved the migration of the water snow line, which created two distinct reservoirs of material. These reservoirs led to the formation of planetesimals that eventually collided and grew into planets 68. This process explains the compositional differences between the inner and outer solar system, as evidenced by meteorite data and astronomical observations 68.
Influence of Star Clusters
The solar system likely formed in a star cluster containing at least 1,000 stars. The cluster environment influenced the solar system's chemical composition, size, and the orbital parameters of its bodies . It is probable that the solar system formed in a leaky cluster, where the likelihood of significant encounters decreased after the first few million years, allowing the solar system to develop its high circularity .
Early Evolution and Differentiation
The early evolution of the solar system involved the formation of a protoplanetary disc and bipolar jets. The dissipation of the solar nebula occurred within a few million years, while the differentiation of asteroidal-sized bodies took 5 to 15 million years . The terrestrial planets formed over approximately 100 million years, incorporating already differentiated bodies and completing their assembly after the solar nebula had dispersed .
Conclusion
The formation of our solar system was a complex process influenced by the collapse of an interstellar cloud, the presence of short-lived radionuclides from a nearby supernova, and the dynamic environment of a star cluster. Meteorites and astronomical observations provide crucial evidence for understanding the stages of planet formation and the distinct reservoirs of material that led to the diverse composition of the inner and outer solar system.
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