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ESA's Cluster sees 'squashed' magnetosphere   Our planet is surrounded by a magnetic shield - the magnetosphere - which protects the Earth from most of the charged particles that are blasted across interplanetary space by explosions of the Sun. In this image, the four Cluster spacecraft are flying in tetrahedral formation in the vicinity of the magnetopause - the outer boundary of the magnetosphere. Here, one spacecraft (right) is still inside the magnetic field, one (centre) is at the undulating magnetopause and the other two have passed into interplanetary space. Events such as this will take place on a regular basis over the next two years. By comparing data from each member of the Cluster quartet, scientists are gathering the first detailed, three-dimensional views of the most important regions in the magnetosphere.
See also an animation illustrating how the four Cluster spacecraft can measure different parts of the waves as they move through the magnetopause.  Data plots from the CIS instrument. These data plots from the CIS experiment on three Cluster spacecraft show the measured population of ions (charged particles) with energy from about 30 eV up to about 30 KeV between 07 and 17 GMT on 14 January 2001. The polar cusp was encountered between 13:30 and 13:50. Detailed comparison of the data on the different spacecraft indicates that the polar cusp was moving toward the Cluster spacecraft at a speed between 10 and 30 km/s. The motion of the cusp in relation to Cluster is shown on the left. Data courtesy of CIS Principal Investigator, Prof. Henri Reme and CIS Co-Investigator Jean-Michel Bosqued (CESR, Toulouse, France)  Artists' impression of the Cluster spacecraft crossing the polar cusp. Particles from the solar wind precipitate through the polar cusp and reach the Earth's atmosphere. Release date: 30 August 2010 |