![Andromeda-Galaxy](https://www.astronomy.com/wp-content/uploads/sites/2/2023/02/Andromeda-Galaxy.jpg)
The Andromeda Galaxy (M31).
Tony and Daphne Hallas
The improved tools available for astronomers to probe the universe have brought about a new understanding of galaxies. From their early years to their eventual fates, these island universes continue to beguile scientists.