The influence of comet passage on the magnetosphere

We make a data analysis and statistical study of possible effects on the ea rth's magnetosphere caused by five passages at different times and under di fferent circumstances of the three comets, Halley, Hyakutake and Hale-Bopp. We point out that while disturbance is entirely possible according to the physical properties of comet's tail, whether or not disturbance will occur depends strongly on the circumstances of the passage.