  The magnetospheres of the outer planets exhibit turbulent phenomena in an
environment which is qualitatively different compared to the solar wind or the
interstellar medium. The key differences are the finite sizes of the
magnetospheres limited by their physical boundaries, the presence of a strong
planetary background magnetic field and spatially very inhomogeneous plasma
properties within the magnetospheres. Typical turbulent fluctuations possess
amplitudes much smaller than the background field and are characterized by
Alfv\'en times, which can be smaller than the non-linear interaction time
scales. The magnetospheres of the outer planets are thus interesting
laboratories of plasma turbulence. In Jupiter's and Saturn's magnetospheres,
turbulence is well established thanks to the in-situ measurements by several
spacecraft, in particular by the Galileo and Cassini orbiter. In contrast, the
fluctuations in Uranus' and Neptune's magnetospheres are poorly understood due
to the lack of sufficient data. Turbulence in the outer planets' magnetospheres
have important effects on the systems as a whole. The dissipation of the
turbulent fluctuations through wave-particle interaction is a significant heat
source, which can explain the large magnetospheric plasma temperatures.
