ESA’s Cluster flies through Earth’s electrical switch   This sketch shows the various regions of Earth’s magnetosphere, being investigated by ESA’s Cluster mission. The position of the four satellites of the Cluster fleet is indicated by the red circle.   This sketch shows a so-called electron diffusion region. It is a boundary just a few kilometres thick that occurs at an altitude of approximately 60000 kilometres above the Earth’s surface, where electrons can be accelerated to approximately one hundredth the speed of light. On 25 January 2005, and for nineteen times in one hour, the Cluster quartet found themselves engulfed in an electron diffusion region.   In a plasma (a gas of charged particles), during magnetic reconnection, magnetic field lines of opposite direction break and then reconnect, forming an X-line magnetic topology. The newly reconnected field lines accelerate the plasma away from the X-line.   On 28 October 2003, the Sun released a coronal mass ejection of immense proportions which travelled in the direction of Earth. Bigger than the Sun itself, it hurtled towards Earth at a speed of over 2000 kilometres per second - five times the normal speed. Release date: 30 August 2010