#IG Phy – Formation of the Solar System and its Structure

The Solar System was formed approximately 4.5 billion years ago from a dense cloud of interstellar gas and dust.

The gas in the cloud that formed the Solar System was mostly hydrogen, with some helium.

Interstellar dust is composed of tiny grains of matter formed from metallic elements such as magnesium, silicon, iron, and molecules like ammonia, carbon monoxide, methane, and nitrogen.

A shockwave from an exploding star (supernova) initiated the process of the cloud collapsing under its own gravity.

As the cloud collapsed, it generated heat, started to swirl, and formed a thin rotating accretion disc.

The center of the accretion disc became the Sun, formed through the process of fusion where hydrogen nuclei fused to form helium nuclei, releasing energy.

The four planets nearest to the Sun (Mercury, Venus, Earth, and Mars) were formed in the cooler outer regions of the accretion disc.

The outer cooler regions of the accretion disc contained frozen matter such as ammonia, methane, nitrogen, and water, forming the gas-giant planets and ice-giant planets.

Gas and dust that did not form into larger objects were blown away by the radiant energy of the Sun.

The planets, minor planets, and dwarf planets were formed from the larger pieces of the accretion disc.