Starship Asterisk*

A lightning researcher at the University of Bath has discovered that during thunderstorms, giant natural particle accelerators can form 40 km above the surface of the Earth. On Wednesday 14th April Dr. Martin Fullekrug will present his new work at the RAS National Astronomy Meeting (NAM 2010) in Glasgow. The image shows a transient airglow or 'sprite' above a thunderstorm in France in September 2009.

When particularly intense lightning discharges in thunderstorms coincide with high-energy particles coming in from space (cosmic rays), nature provides the right conditions to form a giant particle accelerator above the thunderclouds.

The cosmic rays strip off electrons from air molecules and these electrons are accelerated upwards by the electric field of the lightning discharge. The free electrons and the lightning electric field then make up a natural particle accelerator.