Marek Demianski, a frequent visitor in the Astronomy Department, will be here for the 2018-2019 academic year. He received his M.S. and Ph.D. from the University of Warsaw. His permanent position is at the Institute of Theoretical Physics, University of Warsaw. Prof. Demianski’s research centers on cosmology and relativistic astrophysics. He is studying the very early phases of evolution of the universe, the process of formation and clustering of galaxies, and properties of the cosmic microwave background radiation. He is a Co-Principal investigator in two European consortia preparing the Planck Surveyor mission. For four years (1992-1996) he was director of the N. Copernicus Astronomical Center in Warsaw.