How does accretion form planets?

Planetary accretion is the process of building up a planet or planetary formation. Accretion is the process of accumulation or building up, and it happens when objects in space are drawn together by gravitational attraction. These objects can be dust, gas, plasma (ionized "gas"), comet debris, etc. Larger accumulations can result in star formation.

Accretion is the process by which small particles collide and stick together, gradually building up larger and larger bodies. In the context of planet formation, it starts with tiny particles in a protoplanetary disk around a young star. These particles collide and stick, forming larger and larger clumps called planetesimals. These planetesimals then collide and accrete to form protoplanets, which eventually become planets. This process can take millions of years.