What is the outer limits the galaxy being?

The outer limits of a galaxy refer to the farthest reaches of its spiral arms, where the density of stars and interstellar matter decreases significantly.

The Milky Way galaxy, for example, is estimated to have a diameter of approximately 100,000 light-years. The outer limits of its spiral arms are thought to extend out to a distance of around 50,000 light-years from the galactic center.

Beyond this point, the density of stars and gas becomes so low that it is difficult to distinguish individual objects. However, there are still some objects present in these outer regions, such as globular clusters, dwarf galaxies, and dark matter.

Studying the outer limits of galaxies can provide valuable insights into their formation and evolution. For example, simulations suggest that interactions with other galaxies or dark matter halos can affect the shape and structure of a galaxy's outer regions over time.