The magnetic field lines are like the two lanes of traffic on a busy road: close together, but pointing in opposite directions.

ECONOMIST: Hot stuff

The same thing happens with the magnetic field lines, which suddenly reconnect, resulting in a hole a few kilometres wide in the armour of the magnetosphere, through which plasma can spill.

ECONOMIST: Hot stuff

There seems to be no way that particles streaming past the earth along magnetic field lines can make a turn, move at right angles to those lines for a bit and end up inside the magnetosphere.

ECONOMIST: Hot stuff