5 - Star Formation and Planets

Summary

Stars form when vast clouds of gas and dust begin to swirl and collapse with a concentration of matter at the centre. Around the newly born star a proto-planetary disk rotates, out of which planets can later evolve by clumps arising and accumulating ever greater amounts of material. The smaller planets which arise tend to be largely composed of rock, like the first four in our Solar System, whereas the larger ones tend to be gas or ice giants, like the outer four in our system.