Magnetic Reconnection in the Earth’s Magnetosphere

Observations from the Magnetospheric Multiscale (MMS) satellites have recently demonstrated that kinetic processes leading to crescent-shaped electron distributions are central to collisionless magnetic reconnection in the Earth’s magnetosphere. Further investigations are now revealing a number of other characteristics of collisionless magnetic reconnection. Anti-parallel magnetic reconnection at the Earth’s magnetopause is embedded in a region with strong magnetic field fluctuations and turbulence. The turbulence appears to be linked to an instability in the thin current sheet adjacent to the electron diffusion region. Interestingly, moderate and high guide-field magnetic reconnection (ratio > 1) are far more common than expected. This type of magnetic reconnection develops a strong parallel electric field and the energy dissipation is dominated by parallel currents, whereas the dissipation in antiparallel magnetic reconnection is by perpendicular currents. In the Earth’s magnetotail, there appears to be events in which the magnetic reconnection is nearly laminar and behaves as depicted in 2D simulations. On the other hand, there are also events in the Earth’s magnetotail which the magnetic reconnection is embedded in a region of strong turbulence in which electrons and ions are significantly heated and accelerated. In this talk, we summarize the current on-going investigations of magnetic reconnection in the Earth’s magnetosphere and discuss how these may apply to the solar environment.