Laplace's Nebular Hypothesis, proposed by the French mathematician and astronomer Pierre-Simon Laplace in the late 18th century, suggests a theoretical model for the formation of the solar system. The hypothesis is based on the idea that the solar system formed from a rotating cloud of gas and dust, also known as a solar nebula.
Key points of the hypothesis include:
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Initial Cloud of Gas and Dust: The solar system began as a vast, diffuse cloud of gas and dust in space, primarily composed of hydrogen and helium, along with heavier elements.
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Collapse under Gravity: Over time, this cloud began to collapse under its own gravitational attraction, possibly triggered by an external force such as a nearby supernova. As it collapsed, it began to spin faster due to the conservation of angular momentum.
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Formation of a Protoplanetary Disk: As the cloud collapsed, it flattened into a rotating disk, with most of the material concentrating at the center. This central bulge eventually became the Sun, while the rest of the material in the disk started to clump together.
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Accretion of Planets: Within the disk, dust and gas particles began to collide and stick together, forming larger bodies called planetesimals. These planetesimals continued to collide and coalesce to form the planets, moons, and other objects in the solar system.
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Remaining Material: Not all material in the disk contributed to the formation of planets; some remained as smaller bodies, leading to the creation of asteroids, comets, and other small solar system objects.
Laplace's hypothesis was an early attempt to explain the formation of the solar system in a scientific manner, and it laid the groundwork for modern theories of planetary formation. Later developments in astrophysics, including the more refined models of nebular theory and observational evidence from exoplanetary systems, further expanded our understanding of how solar systems form.