Solar system formed
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Formation of the Solar System
Collapse of Interstellar Cloud Material
The formation of the Solar System began approximately 4.56 billion years ago with the collapse of an interstellar cloud of gas and dust under its own gravity Russell2007Nimmo1986. This collapse led to the creation of a rotating, dusty disc around the newly formed Sun. The material within this disc began to coalesce into small planetary bodies known as planetesimals, which served as the building blocks for the planets .
Role of Meteorites and Protoplanetary Discs
Meteorites provide crucial evidence for understanding the early Solar System. Chondrites, the most common type of meteorite, formed from the accretion of material in the dusty disc and were heated, likely by radioactive decay, leading to metamorphosis . Observations of protoplanetary discs around young stars today offer insights into the stages of planet formation, including the lifetime of the solar protoplanetary disc and the duration of different formation stages .
Influence of Stellar Environments
The Solar System likely formed in a star cluster containing at least 1,000 stars, which influenced its chemical composition and the orbital parameters of its bodies . High-density starburst clusters were unlikely environments for the Solar System's formation due to their intense gravitational interactions, making leaky clusters (OB associations) more probable . Additionally, the presence of short-lived radionuclides in meteorites suggests that a nearby supernova may have triggered the Solar System's formation Hester2004MacPherson2011.
Two-Part Formation and Snow Line Migration
Recent studies indicate that the inner and outer Solar System formed from two distinct reservoirs of material, separated by the migration of the snow line—the boundary between regions containing water vapor and solid ice Smith2021Lichtenberg2021. This migration created two separate populations of planetesimals, which grew through collisions to form the planets. This model explains the distinct compositions of the inner and outer Solar System and aligns with meteorite data and observations of protoplanetary discs around other stars Smith2021Lichtenberg2021.
Early Evolution and Impact Events
The early evolution of the Solar System involved significant heating and melting of planetesimals, leading to the formation of various meteorite types, including those made from basalts and iron metal alloys . Large impacts, such as the collision of a Mars-sized body with early Earth, played a crucial role in shaping the diversity of planets and the formation of the Moon . The dissipation of the solar nebula occurred within a few million years, while the terrestrial planets took around 100 million years to form, incorporating already differentiated bodies .
Conclusion
The formation of the Solar System was a complex process influenced by the collapse of interstellar cloud material, the dynamics of protoplanetary discs, and the environment of a star cluster. Meteorites and astronomical observations provide valuable insights into the stages of planet formation and the distinct compositions of the inner and outer Solar System. Understanding these processes helps us comprehend the unique history and evolution of our Solar System.
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