Re: Does Jupiter's magnetic field 'tail' have an effect on Saturn?

First, for the benefit of other readers, most of the planets in the solar system have magnetic fields. On Earth, its magnetic field is familar to anybody who has ever used a compass. The magnetic field of a planet extends into space, forming a region called the planet's magnetosphere. The Sun produces a very dilute wind of particles called the solar wind. The solar wind is both deflected by the magnetic field of a planet and it deforms the outer part of the magnetosphere. Windows to the Universe has some additional discussion (along with pictures) of the Saturnian magnetosphere, and the magnetospheres of other planets are similar to that of Saturn. Jupiter's magnetosphere is particularly impressive as it is the largest structure in the solar system, and, if it could be seen from Earth, it would be at least twice as large as the size of the full Moon.

The solar wind deforms a planet's magnetosphere into a teardrop shape. Stretching away from the Sun is the magnetotail portion of the magnetosphere. As summarized in the Voyager Jupiter Science Summary, during the Voyager mission to Jupiter, the signature of the magnetotail was detected directly for the first time. As you note, Jupiter's magnetosphere is so large that its magnetotail extends to or past the orbit of Saturn. Thus, at times, Saturn passes through the magnetotail of Jupiter.

While the magnetosphere of Jupiter has an impressive size, it is not substantial in comparison to a dense object like a planet. After all, we walk through the Earth's magnetic field all of the time. Our spacecraft to the outer planets pass through their magnetospheres without a problem. A vivid illustration of a spacecraft passing through a planet's magnetosphere was collected recently by the Cassini Radio and Plasma Wave Science instrument, which recorded the abrupt change in radio emission at the location where the solar wind was impacting the Saturnian magnetosphere.

As luck would have it, though, Voyager 2 was approaching Saturn at about the same time (in 1981) that Saturn passed into Jupiter's magnetotail. While Jupiter's magnetotail has no impact on the planet itself, it does affect Saturn's magnetosphere. As the above link to the Cassini Radio and Plasma Wave Science instrument indicates, when the solar wind impacts and interacts with a planet's magnetosphere, radio radiation can be produced. (The sounds collected at the above link were formed by taking the radio radiation detected by Cassini and converting them to sound.) When Saturn passed into the Jovian magnetotail, the solar wind was no longer impacting its magnetosphere. The result was that Saturn's radio emission essentially ceased for a period of time in 1981. This cessation of Saturn's radio emission is summarized in the Voyager Saturn Science Summary and discussed in much more depth in the technical paper, "Radio Emission Signature of Saturn Immersions in Jupiter's Magnetic Tail" (Desch 1983, J. Geophys. Res., vol. 88, p. 6904).