EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Toward constraining Saturn's rotation rate by interior modeling

Nadine Nettelmann1 and Jonathan J. Fortney2
Nadine Nettelmann and Jonathan J. Fortney
  • 1Institute of Planetary Research, German Aerospace Center, Berlin, Germany (
  • 2Dept. of Astronomy and Astrophysics, University of California, Santa Cruz, USA

The rotation rate of the outer planet Saturn is not well constrained by classical measurements of periodic signals [1]. Recent and diverse approaches using a broad spectrum of Cassini and other observational data related to shape, winds, and oscillations are converging toward a value about 6 to 7 minutes faster than the Voyager rotation period.
Here we present our method of using zonal wind data and the even harmonics J2 to J10 measured during the Cassini Grand Finale tour [2] to infer the deep rotation rate of Saturn. We assume differential rotation on cylinders and generate adiabatic density profiles that match the low-order J2 and J4
values. Theory of Figures to 7th order is applied to estimate the differences in the high-order moments J6 to J10 that may result from the winds and the assumed reference rotation rate. Presented results are preliminary as the method is under construction [3].

[1] Fortney, Helled, Nettelmann et al, in: 'Saturn in the 21st century', Cambridge U Press (2018)
[2] Iess, Militzer, Kaspi, Science 364:2965 (2019)
[3] Nettelmann, AGU Fall Meeting, P066-0007 (2020)


How to cite: Nettelmann, N. and Fortney, J. J.: Toward constraining Saturn's rotation rate by interior modeling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6442,, 2021.

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