Part 1: I present an analysis of Gaia DR1 data in terms of the vertical velocity of stars as function of their radial position and angular momentum. The mean vertical velocity shows a strong evidence for both a stellar warp and a vertical bending wave, which could have been triggered by interaction with SgrA*. I may also report on ongoing work using Gaia DR2. Part 2: I present simulations and analytical insight into the formation of tidal debris from a satellite on a disc orbit, such as 47Tuc. The debris from such a progenitor does not form a thin stream or tail, but a vertically extended ribbon wrapping around the Milky Way and with vertical extent comparable to that of the progenitor's orbit. I discuss the implications for detection and interpretation of such tidal ribbons.