How Were The Stars Formed?

The Milky Way galaxy was once ablaze with bright young stars. Today, star formation has calmed down, but we glimpse intense pockets of gas that are forming massive stars, testifying to the brilliant past. Stars form in clouds of interstellar gas that orbit their host galaxy. The clouds acquire more mass as gas accumulates, and the gaseous nebulae are soon massive enough to become unstable, due to the pull of their own gravity. As the clouds collapse, their central regions fragment into dense clumps of cold gas that eventually form stars.

Dust particles are the key ingredients that eventually coalesce to form a disk-like structure with rocky cores that orbit the forming sun and agglomerate into planets. The entire solar system was formed out of interstellar grit.