Planetary formation is the process by which planets develop from a cloud of gas and dust surrounding a young star. This process begins with the accumulation of particles that collide and stick together, forming larger bodies called planetesimals. Over time, these planetesimals merge to create protoplanets, which can eventually become full-fledged planets like Earth and Mars. The formation of planets is influenced by various factors, including the distance from the star and the composition of the surrounding material. The solar system is a prime example of this process, showcasing how different planets formed in distinct regions, leading to the diverse characteristics we observe today.