Mini-magnetospheres above the lunar surface and the formation of lunar   swirls
  In this paper we present in-situ satellite data, theory and laboratory validation that show how small scale collisionless shocks and mini-magnetospheres can form on the electron inertial scale length. The resulting retardation and deflection of the solar wind ions could be responsible for the unusual "lunar swirl" patterns seen on the surface of the Moon. 
R. A. Bamford, B. Kellett, W. J. Bradford, C. Norberg, A.Thornton, K.   J. Gibson, I. A. Crawford, L. Silva, L. Gargate, R. ...
astro-ph.EP physics.plasm-ph