1. A regular period for Saturn’s magnetic field that may track its internal rotation Nature, Volume 441, Issue 7089, pp. 62-64 (2006)

2. Saturn’s rotation is difficult to determine There is no solid surface from which to time it. The alternative ‘clock’—the magnetic field—is nearly symmetrically aligned with the rotation axis.

3. Saturn is an intense radio emitter. The primary component of this radiation is called Saturn kilometric radiation (SKR). The radio rotation period is presumably that of the planet's magnetic field.

4. Previous observations (the Saturnian kilometric radiation) Voyager 1 & 2 10 h 39 min 24 s +/- 7s Ulysses 10 h 39 min 22 s (the radio period is not constant) Cassini 10 h 45 min 45 s +/- 36 s The reasons for this shift are poorly understood.

5. Cassini-Huygens mission Cassini-Huygens is a joint NASA/ESA/ASI space mission intended to study Saturn and its moons. launched on October 15, 1997 entered orbit on Jun. 30, 2004.

6. These residuals are calculated by subtracting the estimated contribution of the internal planetary field and the external magnetodisk current sheet. Periodicity in Saturn’s magnetic field

7. P =10 h 47 min 6 s +/- 40 s The power spectra of the residuals

8. Conclusion the first accurate and direct measurement of Saturn’s magnetic field periodicity

9. Thank you