huge bursts of particles and
electromagnetic energy known as coronal
mass ejections (CMEs). Most shoot
harmlessly into space. But if directed at the
Earth, the fast-moving particles can smash
into satellites, interfere with
communications and damage groundbased
electronic devices. Major CMEs
trigger violent changes in the Earth’s
magnetic field, creating geomagneticallyinduced
currents (GICs). These can surge
through pipelines and high-tension power
cables, damaging transformers and
triggering mass blackouts. CMEs were
responsible for the notorious Carrington
Event of 1859, which blacked out
telegraph systems in Europe and America.
Efforts to minimise the effects of
CMEs focus on early warning and
damage limitation. Space-based
observations can spot CMEs a day or
more before they strike. This allows
power operators to take measures, while
satellites can be re-orientated to reduce
the risk of damage. Some power
networks are being fitted with GIC surge
detectors – these mop up the currents
and protect transformers at key points in
the electric grid.
