ESA's Cluster solves an auroral puzzle   Cluster satellites study the effects of solar wind. Artist's impression.     More about Cluster     The configuration of spacecraft and the Earth when the breakthrough was made. On 18 March 2002, NASA's IMAGE was closer to the Earth and observing an aurora that contained a dayside proton auroral spot (see bottom left picture). At the same time, ESA's Cluster quartet then passed overhead returning proton data (see top left graph) that showed a magnetic reconnection was taking place and that protons were leaking through Earth's magnetic shield. These protons were then being funnelled into Earth's atmosphere along the magnetic field to form the spot. Release date: 22 May 2003