Geometry of the magnetospheric tail and auroral current systems

Abstract

Measurements of the earth's magnetic field in the magnetospheric tail by Explorer 10 [Heppner et al., 1963], Explorer 14 [Cahill, 1964], and particularly by Imp 1 [Ness, 1965] show that the polar field lines are swept back into a magnetospheric tail somewhat in the manner indicated by Figure 14 of Ness [1965] or Figure 1 of this letter. Similar configurations have been predicted by Dungey [1961] and by Dessler [1964], Dessler and Juday [1965]. Dungey's model and its modifications by Levy et al. [1964] and by Axford et al. [1965] all have a neutral point or line at some distance behind the earth, whereas Dessler and Juday's model has an open tail extending to a distance longer than an astronomical unit. It is not yet possible to choose between these different models on the basis of the measurements [Ness, 1965].