ESA Science & Technology - Simulation of plasma pressure in the magnetosphere on 21-22 January 2005

On 20 January 2005, the ESA/NASA SOHO spacecraft detected an explosion on the Sun which ejected a huge cloud of plasma (electrically charged gas) into space. Subsequent observations indicated that this was one of the fastest coronal mass ejections (CMEs) during solar cycle 23. As a result, it took only 34 hours for the cloud of plasma to cross the 150 million km gulf between the Sun and Earth, compared with the typical time of 3 to 4 days. A consequence of this was that the fast-moving cloud acted like a snow plough, driving into slower-moving solar wind material ahead of it and compressing the plasma so that it piled up in a high density - high temperature sheath region, preceded by an interplanetary shock.

The solar filament struck the Earth at about 18:45 UT, reaching peak pressure by about 19:10 UT. The simulation begins just after this when a cold dense plasma sheet forms by capture of the solar filament material (which approached from the left) within the magnetosphere. This is seen by the high pressure on the flanks of the magnetosphere and just inside the magnetopause on the dayside. The black lines are magnetic field lines, which are seen stretching out in response to the high dynamic pressure (high densities).

The simulation was made using the Space Weather Modeling Framework developed by the Center for Space Environment Modeling at the University of Michigan. The view is from the dusk side. The series of three arrows at the far right are the Bx-, By-, and Bz-components of the interplanetary magnetic field. When Bz points upward the IMF is northward (usually associated with magnetic quieting); when Bz points downward, the IMF is southward creating disturbed conditions. Pressure levels are colour-coded from red through green to blue to show high pressure, medium pressure and low pressure.

Credit: Visualization by Darren DeZeeuw, Center for Space Environment Modeling, University of Michigan, USA