Cometocentric distance of Rosetta (km) as function of time is shown with a black line (right y-axis). The mean speed of the observed solar wind protons (km/s on the right y-axis) is shown with occurrence in time-velocity bins using a colour-scale. The four periods discussed in the text are marked with numbers in the top of the plot. The beginning of the data, from 28 May 2015, is marked with an arrow.