High-resolution measurements from NASA spacecraft have unraveled the mysteries of magnetic reconnection around Earth – a phenomenon whereby magnetic field lines break and reconnect, releasing energy and accelerating particles. Because of the importance of magnetic reconnection in many laboratory and space environments, this result has opened up a new window into this universal process, the authors say, one that is otherwise poorly understood. The magnetosphere is the region of space surrounding Earth where the dominant magnetic field is the magnetic field of Earth, rather than the magnetic field of interplanetary space. Field lines in Earth's magnetic field rearrange and reconnect, and a better understanding of this process is an important goal for plasma physics. While the Earth's magnetosphere has been explored by many spacecraft missions, measurements of magnetic reconnection on the electron scale are lacking. As such, scientists still don't fully understand what causes reconnection. In March 2015, NASA launched four spacecraft as part of the Magnetospheric Multiscale (MMS) mission, which was designed to perform a high-resolution space experiment on magnetic reconnection at the electron scale. James Burch and colleagues analyzed the results and determined the reconnection process is driven by the electron-scale dynamics. The results will aid scientists' understanding of magnetized plasmas, including those in fusion reactors, the solar atmosphere, and magnetospheres of the Earth and other planets.
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