Magnetic Mercury sapped by the sun

摘要

Mercury's puny magnetic field may be so weak thanks to constant wrangles with the solar wind. NASA's Mariner 10 mission detected a magnetic field around our solar system's innermost planet in 1974, but its cause remained a mystery - until recent measurements suggested that Mercury's core may be partly molten. As with Earth, these "moving parts" could act like a dynamo, generating electricity and consequently a magnetic field. But that cannot explain why Mercury's field is so weak, says Karl-Heinz Glassmeier at the Institute for Geophysics and Extraterrestrial Physics at Braunschweig, Germany.