Rotation of the magnetic field clock angle during an ICME. (a) Magnetic field strength. (b) Three components of the magnetic field. (c) Local magnetic field clock angle in the solar wind and the Venusian magnetosheath. Three time intervals from 10 Sep. 2006 20:30:00 to 11 Sep. 2006 02:30:00, 11 Sep. 2006 04:00:00 to 06:00:00 and 09:00:00 to 13:00:00 are focused on. For each time interval, the clock angle variations are fitted with cyan and magenta dashed lines based on the data gathered in solar wind and magnetosheath, respectively. The rotation speeds are indicated by the slopes of the dashed lines.