"... In the case of the Carrington event of 1859, the most severe coronal mass ejection known to have occurred, the propagation time between the Sun and the Earth, at a speed of 2,300 kilometres per second, was seventeen and a half hours. The way to avert the most serious impacts would be to make adjustments to the operation of the electricity grids before the storm struck (see Space Studies Board 2008, Chapter 7). The necessary actions would have to be taken very quickly and in a coordinated way in order to be effective, so they would have to be carefully planned in advance, preferably in an international context."