This 21st volume in the series contains 15 invited reviews and highlight contributions presented during the 2008 International Scientific Conference of the German Astronomical Society on the topic of "e;New Challenges to European Astronomy"e;, held in Vienna, Austria.The papers discuss a wide range of hot topics, including cosmology, high-energy astrophysics, astroparticle physics gravitational waves, extragalactic and stellar astronomy -- together representing the roadmap for modern astrophysical research.