Stars are formed in nebulas of gas and dust via gravitational collapse (accretion). The remaining gas and dust that is swirling around the star flattens out in

Stars are formed in nebulas of gas and dust via gravitational collapse (accretion). The remaining gas and dust that is swirling around the star flattens out into a disk (because of angular momentum). Planets gradually form in this disk, again via accretion (snowball effect). https://en.m.wikipedia.org/wiki/Protoplanetary_disk https://en.m.wikipedia.org/wiki/Protoplanetary_disk https://en.m.wikipedia.org/wiki/Accretion_(astrophysics) https://en.m.wikipedia.org/wiki/Accretion_(astrophysics)