Expected immersion of Saturn's magnetosphere in the jovian magnetic tail

Voyager 2 approaches Saturn (\[Saturn] ) this month, August 1981, after the possible encounter1,2of the planet with the tail or wake3of Jupiter (\[Jupiter]). With the magnetic flux in the tail of φ≅2 × 1012Wb (refs 4,5) a simple model suggests that the tail is very long (7–15 AU) and wide enough (∼0.6 AU) to engulf Saturn. This could result in a sudden drop (by a factor of ∼40) of the ram pressure on the magnetosphere of Saturn. The ensuing inflation of the magnetosphere may cause effects observable from Voyager 2 and/or Earth-orbiting satellites, including a flare-up of kilometric radiation and enhancement of the Lyα limb brightening. Such events, if observed, could shed light on the magnetic and plasma nature of the jovian tail and on the electrodynamics of the saturnian magnetosphere.