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How does magnetic reconnection transfer solar-wind energy into Earth’s magnetosphere?
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Ionosphere and magnetosphere
The layers of Earth's atmosphere, with a yellow line showing the air temperature at various heights.
Magnetic reconnection is the primary physical mechanism that transfers energy, mass, and momentum from the solar wind into Earth’s magnetosphere. This process involves the explosive conversion of magnetic energy into the kinetic energy of magnetospheric plasma.12
The transfer occurs through the following stages:
- Dayside Reconnection: When the solar magnetic field (carried by the solar wind) is oriented antiparallel to Earth’s magnetic field, the two fields connect at the dayside magnetopause. This allows solar plasma to enter the magnetosphere and links interplanetary magnetic field lines to geomagnetic field lines.123
- Energy Transport: The connected field lines are dragged away from the Sun by the solar wind, stretching the magnetosphere into a long magnetotail. This process generates a magnetospheric electric field that projects along field lines into the ionosphere, driving powerful electric currents.123
- Nightside Reconnection: To maintain equilibrium, magnetic flux must return to the dayside. This occurs in the magnetotail, where field lines disconnect from the solar wind and reconnect, releasing stored energy that can accelerate particles toward Earth’s polar regions, resulting in auroral displays.124