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How does magnetic reconnection on Earth’s dayside allow solar plasma into the magnetosphere?

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Space weather Earth's full North Polar auroral oval, in an image taken in ultraviolet light by the U.S. Polar spacecraft over northern Canada, April 6, 1996. In the colour-coded image, which simultaneously shows dayside and nightside auroral activity, the most intense levels of activity are red, and the lowest levels are blue. Polar, launched in February 1996, was designed to further scientists' understanding of how plasma energy contained in the solar wind interacts with Earth's magnetosphere.

Magnetic reconnection is the primary physical mechanism that allows solar plasma to enter Earth’s magnetosphere.1

On the dayside of the magnetosphere, this process occurs at the intersection of solar magnetic field lines—carried by the solar wind—and Earth’s geomagnetic field lines. When these oppositely directed magnetic fields are brought together at an x-type neutral line, they become "unfrozen" from the plasma and diffuse, allowing the field lines to break and reconnect.21

Through this reconnection, the interplanetary magnetic field (IMF) lines become linked with Earth’s geomagnetic field lines. Because the IMF is frozen into the solar wind, the reconnected field lines provide a pathway for solar plasma to enter the magnetosphere, where it is subsequently accelerated and energized. This process changes the topology of the magnetic field, effectively opening the magnetosphere to the solar wind and facilitating the transfer of mass, energy, and momentum into Earth's space environment.231