THE mysterious electrical circuitry behind the northern lights has been
revealed for the first time by a team of satellites travelling through the upper
reaches of an aurora. Goran Marklund of the Royal Institute of Technology in
Stockholm, Sweden, and co-workers got their data from the European Space
Agency鈥檚 four Cluster satellites. It shows electrons draining out into space
from the ionosphere鈥攖he charged part of the atmosphere
(Nature, vol 414, p 724).
Patrick Newell of Johns Hopkins University in Laurel, Maryland, says once the
ionosphere is drained, huge electric fields build up. Eventually electrons are
catapulted down towards Earth from the magnetosphere, above the ionosphere,
sparking off a light show in the upper atmosphere. 鈥淭his solves the puzzle of
how the electric fields are sustained,鈥� he says.