Formation of the Solar System

Collapse of Solar Nebula and Birth of the Sun

According to the Nebular Hypothesis, the Solar System formed approximately 4.6 billion years ago from a giant cloud of gas and dust known as the solar nebula. This nebula likely originated from the remnants of older stars that had gone supernova.

Under the influence of gravity, the nebula began to collapse inward. As it collapsed, it started to rotate faster, flattening into a disk-like structure. Most of the material was pulled toward the centre, where it formed the proto-Sun. Over time, temperatures in the core of this proto-Sun increased due to the pressure from gravitational collapse, eventually igniting nuclear fusion, marking the birth of the Sun.

Formation of Protoplanetary Disk

Surrounding the proto-Sun, the remaining material flattened into what is known as a protoplanetary disk. This disk contained gas, dust, and various elements, including hydrogen, helium, and heavier materials like silicates and metals.

Within the protoplanetary disk, small particles began to collide and stick together, a process driven by electrostatic forces. Over time, these particles grew into larger clumps, eventually forming kilometre-sized objects known as planetesimals. These planetesimals would become the building blocks of planets.

Accretion of Planetesimals and Protoplanets