When you take a large amount of mass and put it all together in a small volume of space, you fully expect gravity to do its thing, and eventually collapse things down as far as they’ll go. You can imagine that for compact masses with large distances between them — like planets in the solar system or stars in the galaxy — this will take a very long time: longer than the age of the Universe.
But what about globular clusters: hundreds of thousands of stars collected in a spherical region of space just a few tens of light years across? While there is some collapse that occurs, there’s also ejection and mass segregation, keeping the clusters intact for timescales far longer than the Universe has been around.
Yet we don’t know everything about these objects; find out what we do (and don’t) know on this edition of Jillian Scudder’s Astroquizzical!