Orientation of the Magnetic Fields in Interplanetary Flux Ropes and Solar Filaments

Coronal mass ejections (CMEs) are often associated with erupting magnetic structures or disappearing filaments. The majority of CMEs headed directly toward the Earth are observed at 1 AU as magnetic clouds—the region in the solar wind where the magnetic field strength is higher than average and there is a smooth rotation of the magnetic field vectors. The three-dimensional structure of magnetic clouds can be represented by a force-free flux rope. When CMEs reach the Earth, they may or may not cause magnetic storms, alter Earth's magnetic field, or produce the phenomena known as auroras. The geoeffectiveness of a solar CME depends on the orientation of the magnetic field in it.