Solar System Formation: The Nebular Hypothesis

Solar System Formation

The Nebular Hypothesis

• The most widely accepted theory of solar system formation
• Proposes that the solar system formed from a giant cloud of gas and dust called the solar nebula
• The nebula collapsed under its own gravity, beginning to spin faster and flatten into a disk shape

Stages of Formation

1. Gravitational Collapse: The solar nebula collapses, with the Sun forming at the center
2. Planetesimal Formation: Small particles stick together to form larger bodies called planetesimals
3. Accretion: Planetesimals collide and merge, growing larger and more massive
4. Planetary Differentiation: Heavy elements sink to the center of the forming planets, while lighter materials rise to the surface
5. Atmospheric Formation: Gases are released from the forming planets, creating atmospheres

Evidence Supporting the Nebular Hypothesis

• Meteorites: Contain particles from the early solar system, with similar composition to the Sun
• Comets: Have highly elliptical orbits, suggesting they originated from the outer reaches of the solar system
• Kuiper Belt: A region of icy bodies beyond Neptune, thought to be remnants of the solar nebula
• Planetary Orbits: The similarity in orbital planes and direction of rotation among the planets suggests a common origin

These notes provide a concise overview of the solar system's formation, focusing on the Nebular Hypothesis and its supporting evidence.