Fundamental Unsolved Problems in Astrophysics

There is given a list and discussion of what are arguably the top 20 unsolved problems in astrophysics today. The list ranges from particle physics to cosmology. Possible resolutions are noted, but without judgement. Perhaps the most remarkable aspect of the discussed problems is that they are closely interrelated. This opens the prospect that a solution to one or a few may lead to a significantly better understanding of modern astrophysics.