How the Solar System Formed: From Dust Cloud to Planets

Our solar system began about 4.6 billion years ago from a giant molecular cloud of gas and dust called a solar nebula. A nearby supernova may have triggered its collapse. As the cloud contracted, it spun faster and flattened into a disk.

Most material gathered at the center, forming the Sun. Remaining material formed a protoplanetary disk where dust grains collided and stuck together, growing into planetesimals. Through accretion, these formed the planets.

Close to the Sun, only rocky material survived, forming the terrestrial planets. Farther out, ice could remain solid, allowing gas giants to grow massive enough to capture hydrogen and helium..