How do planets form? Thousands of extrasolar planets have been discovered to date, and yet we still do not know how planets form out of the galaxy’s raw materials of interstellar gas and dust. Astrophysicists have made some progress by using supercomputer models to try to interpret new exciting images of planetary nurseries – protoplanetary disks of gas and dust. The problem, though, is that the conditions in interstellar space are so different from those on Earth that we do not know how familiar compounds, such as rock or ice, would behave. In particular, extremely low material density and ultra-weak gravity are hard to reproduce in the laboratory. In recent years experiments have been carried out on-board parabolic flights, which can attain zero gravity conditions. The resulting conditions are thus much closer to those in protoplanetary disks. Combined with supercomputer simulations, these experiments are advancing our understanding of how planets form. Researchers at the University of Zurich, in collaboration with the University of Bern, are pioneering this new field of research thanks to parabolic flights hosted by the UZH SpaceHub.