Effect of internal gravitational coupling on Titan's non-synchronous rotation
Article first published online: 27 AUG 2008
Copyright 2008 by the American Geophysical Union.
Geophysical Research Letters
Volume 35, Issue 16, August 2008
How to Cite
2008), Effect of internal gravitational coupling on Titan's non-synchronous rotation, Geophys. Res. Lett., 35, L16202, doi:10.1029/2008GL034744., , and (
- Issue published online: 27 AUG 2008
- Article first published online: 27 AUG 2008
- Manuscript Accepted: 16 JUL 2008
- Manuscript Revised: 8 JUL 2008
- Manuscript Received: 20 MAY 2008
- planetary rotation;
- planetary atmosphere;
- planetary interior
 Variations in the spin period of Titan have been detected by the Cassini radar observations. Angular momentum exchange between Titan's surface and the atmosphere over seasonal time scales corresponding to Saturn's orbital period of 29.5 year is the most likely cause of the observed non-synchronous rotation. The measured rotation rate can be explained if Titan's icy crust is rotationally decoupled from the interior in the presence of a subsurface ocean. However, we show that Titan is likely to rotate almost as a rigid body even when it has an internal ocean because of a substantial internal gravitational coupling between the crust and the interior. The predicted surface rotation rate will be further reduced due to Saturn's torque, but can approach to the observed value if other factors, such as larger atmospheric torque, smaller equatorial flattening or viscous relaxation of the icy crust are considered.