Artist's impression of the neutral sheet oscillations observed in Earth's magnetotail by the four ESA/NASA Cluster spacecraft (in blue) and the CNSA/ESA Double Star TC-1 spacecraft in red.

The five spacecraft were engulfed by waves of electrical and magnetic energy as they travelled through Earth’s night-time shadow on 5 August 2004.

The data collected by the spacecraft are giving scientists an important clue to the effects of 'space weather' on Earth’s magnetic field.