Magnetic Reconnection in the Earth's and 
                     Planetary Magnetospheres 
         
Tatsuki Ogino and Keiichiro Fukazawa

Response of the earth's and planetary magnetospheres to changes in the 
interplanetary magnetic field (IMF) is determined by two factors: The 
extent to which the interplanetary magnetic field and the geomagnetic 
field are antiparallel and the relative velocity of the reconnected 
field lines in the direction perpendicular to the magnetic field. We 
have used a three-dimensional global magnetohydrodynamic simulation 
of the interaction between the solar wind and magnetosphere to carry 
out a systematic investigation of the effects of the orientation of 
the IMF and dipole tilt on magnetospheric structure and dynamics.
The combination of dipole tilt and finite IMF By and Bz leads to 
complex structures in the magnetosphere with no symmetry planes. The 
addition of the Bx component to the IMF adds dawn-dusk and 
north-south asymmetry to the dayside magnetic reconnection. This 
tendency becomes larger when the solar wind Alfve'n Mach number is 
lower. Moreover, IMF By component becomes more important for Jupiter 
and Saturn due to the Parker spiral effect.