There are many varying interpretations revolving around the accretion model.

In one theory, ‘Core Accretion’, the first planets to emerge from the whirling disk of gas and debris that surrounds a newborn star are gas giants like our Jupiter or Saturn. Most astronomers believe they form by accretion.

Tiny dust grains stick together, forming larger grains that collide to form still larger lumps that eventually yield solid cores about ten times the mass of the Earth.

These cores, with their powerful gravity, suck in gas from the disk to create a giant, gas cloaked planet. This process would take many millions of years.