Titan's rotation reveals an internal ocean and changing zonal winds.
Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of approximately 0.36 degrees per year in apparent longitude and is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere, but only if Titan's crust is decoupled from the core by an internal water ocean like that on Europa.
Lorenz
Ralph D
RD
Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. ralph.lorenz@jhuapl.edu
Stiles
Bryan W
BW
Kirk
Randolph L
RL
Allison
Michael D
MD
Del Marmo
Paolo Persi
PP
Iess
Luciano
L
Lunine
Jonathan I
JI
Ostro
Steven J
SJ
Hensley
Scott
S
D001272:Atmosphere; D005118:Extraterrestrial Environment; D007053:Ice; D018539:Saturn; D018531:Spacecraft; D014867:Water; D014919:Wind
D007053:Ice; D014867:Water