Describe the nebular hypothesis of earth’s origin
Biology · High School · Mon Jan 18 2021
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The nebular hypothesis is a widely accepted theory that explains the formation and evolution of the solar system, including the Earth. It was first proposed in the 18th century by Emanuel Swedenborg and further developed by Pierre-Simon Laplace. Here's a step-by-step description of how the nebular hypothesis describes Earth's origin:
1. Nebula Formation: The process begins with a giant cloud of gas and dust in space, known as a nebula. This could be the result of the remnants from a previous star's explosion (supernova) or just the natural clumping of particles within the galaxy.
2. Nebula Collapse: The nebula experiences a collapse, which can be triggered by external forces such as the shockwave from a nearby supernova or simply by the gravitational instabilities within the cloud.
3. Disk Formation: As the nebula collapses, it begins to spin and flatten into a rotating disk called a protoplanetary disk, with the vast majority of the mass congregating at the center to eventually form the Sun.
4. Condensation and Accretion: Within this disk, particles of dust and gas start to stick together through static electricity and later through gravity, forming clumps that grow over time. These increasing clumps are known as planetesimals.
5. Planetesimal Growth: Through accretion (the process of particles sticking together), these planetesimals grow larger and become protoplanets. As they increase in size, their gravitational influence also grows, allowing them to attract more material and further increase in mass.
6. Planetary Formation: Over time, through multiple collisions and continuous accretion, these protoplanets become full-fledged planets. This is how Earth and other planets in our solar system would have formed.
7. Clearing the Disk: Eventually, the young Sun would have emitted strong solar winds and radiation, clearing the remaining gas and dust from the protoplanetary disk. What remains is a relatively clean solar system with planets in stable orbits around the Sun.