The Core Accretion Model

The Core Accretion Model explains how planets, especially those like Earth, form in space. It begins with tiny particles in a protoplanetary disk around a young star sticking together and gradually building larger bodies called planetesimals. These grow through collisions, forming a solid core. When the core becomes massive enough, its gravity attracts surrounding gas and dust, creating an atmosphere. This process continues until the planet reaches its final size. Essentially, it's a step-by-step buildup from small particles to fully formed planets, driven by gravity and collisions over millions of years.