Jupiter's magnetic tail

Voyager 1 observations of the Jovian magnetosphere are discussed which are most naturally interpreted in terms of a well-developed magnetic tail on the nightside of the planet. It is shown that this tail, with a 'neutral sheet' separating the upper and lower lobes of opposite field polarity, is formed and controlled by external forces associated with the solar wind. The inner magnetosphere's current tail is found to merge with the magnetotail's neutral sheet. It is concluded that this configuration leads to a strong local-time control of the outer Jovian magnetosphere rather than planetary control.