In a world where intergalactic wars are a common topic for movies, it is hard to imagine that the discovery of galaxies was made less than a century ago. In fact, it was one of the key astrophysical milestones of the first half of the 20th century, along with the revelation of the expansion of the Universe and the understanding of the source of the stars’ energy. The second half of last century saw the unexpected discovery of fantastic objects and extreme events in the Univer