Encyclopedia of the Solar System 2nd ed

71 6 Encyclopedia of the Solar System

(b)

(a) FIGURE^21 (a) Dynamic spectra

of Saturn’s SKR emission. This

illustrates a dramatic intensification

of the SKR in response to an

interplanetary shock that passed

Cassiniat about 20:30 on June 8,

2004. (b) A high temporal and
      spectral resolution record of SKR
      obtained byCassini. This
      spectrogram illustrates the complex
      structure and variations in the SKR
      spectrum, which is also typical of
      cyclotron maser emissions at Jupiter
      and Earth. (After Kurth, et al.,
      2005, High Spectral and Temporal
      Resolution Observations of Saturn
      Kilometric Radiation.Geophys.
      Res. Lett. 32 , L20S07,
      doi:1029/2005 GL022648.)

shadowing conditions to theVoyagerera late inCassini’s
orbital tour, so such speculation can be tested.

3.7 Uranus and Neptune

Like Saturn’s radio emissions, both smooth and bursty com-
ponents are apparent in the radio emissions from Uranus

and Neptune, and these emissions probably originate in the

southern auroral regions of the planets. Note, though, that

the magnetic fields of these planets are inclined by large

angles (47◦for Uranus, 59◦for Neptune) with respect to

their rotational axes, and hence the auroral regions are not

near the rotation poles. The periodicity of the emissions

leads to the determination of the rotation periods of both