Protoplanet Hypothesis and Planet Formation

Protoplanet Hypothesis Overview

• Solar system originated approximately 5 billion years ago from a vast cloud of dust and gas, called a nebula.
• The nebula primarily consisted of hydrogen and helium, situated in the Orion arm of the Milky Way galaxy.
• Gravitational forces caused the cloud to contract, leading to the formation of a proto-Sun at the center.

Planet Formation Process

• Dust particles condensed under gravity, forming proto-planets which accreted materials such as frozen water, ammonia, methane, and various metals.
• The remaining materials surrounded the proto-Sun and formed a rotating disc, from which the planets emerged.
• Momentum transferred outward during this process contributed to the formation of the solar system's architecture.

Characteristics of Terrestrial and Jovian Planets

• Terrestrial planets, closest to the Sun, lost their outer gases due to intense solar heat, resulting in rocky surfaces.
• Jovian planets, located farther from the Sun, retained their gaseous envelopes and possess gas-dominated surfaces.

Moon Formation

• Moons formed when smaller dust particles, captured by a planet's gravitational pull, began to orbit these planets.
• The Earth’s moon is hypothesized to have formed from a massive collision with a large object, supported by similarities in composition to Earth's mantle.