Disc of Galaxy

This site tells the story of the history of the universe. Click Earlier and Later to follow the story.
Note: Many facts have been simplified to make them easier to understand.
Our new free weekly podcast Time Crystal tells this story as sci-fi fantasy

In young spiral galaxies like the Milky Way, not all the gas was pulled into globular star clusters. Some of it was left behind, and gravity pulled this in a different direction. It fell down towards the middle of the galaxy. The galaxy was slowly spinning round, and this spin threw the gas out into the shape of a flat disc with a bulging center. We do not know when the disc formed. We guess it was around 12 billion years ago.