Planetary formation is a complex process that happens over millions of years. It starts with a cloud of gas and dust in space, called a nebula. Gravity pulls the gas and dust together, forming clumps that eventually become protoplanets. As these protoplanets continue to grow, they can collide and merge with other protoplanets, forming even larger planets. Once the planet reaches a certain size, it can start to attract gas from the surrounding nebula and become a gas giant like Jupiter.