The constant flow of material – the solar wind – intensifies after a solar flare or a coronal mass ejection. Earth’s magnetic field shields us from harmful electrically-charged particles in solar wind, but also causes some particles in space to be accelerated along magnetic field lines towards the magnetic poles. The aurorae offer visual displays of these charged particles as they hit the outer atmosphere of the planet. Instead of a symmetrical distribution of energy between the northern and southern hemispheres through the year, scientists have used data from ESA’s Swarm mission, to discover that electromagnetic energy is preferentially channelled to the northern hemisphere.