The magnetosphere of Mercury.

Mercury's intrinsic magnetic field is strong enough to stand off the solar wind well above the surface of the planet under usual solar wind conditions. Thus, it has a magnetopause and a bow shock which are quite similar to their terrestrial counterparts, albeit much smaller in linear dimension. However, the absence of any significant atmosphere or ionosphere alters the flow of current in the Mercurian magnetosphere from the patterns at the Earth and may affect the transfer of energy from the solar wind to the magnetospheric plasma. Thus, the magnetosphere of Mercury is unique in the solar system. In the limited data provided by Mariner 10, Mercury's magnetosphere strongly resembles a miniature terrestrial magnetosphere in which everything simply happens more quickly and repeats more often than in the terrestrial magnetosphere.