A Primordial Origin of the Laplace Relation Among the Galilean Satellites
S. J. Peale,*
Man Hoi Lee
Understanding the origin of the orbital resonances of the Galilean
satellites of Jupiter will constrain the longevity of the extensive
volcanism on Io, may explain a liquid ocean on Europa, and may guide
studies of the dissipative properties of stars and Jupiter-like
planets. The differential migration of the newly formed Galilean
satellites due to interactions with a circumjovian disk can lead to the
primordial formation of the Laplace relation n1
- 3n2 + 2n3 = 0, where the ni are the mean orbital angular velocities of Io, Europa, and Ganymede, respectively. This contrasts with the formation of the resonances by differential expansion of the
orbits from tidal torques from Jupiter.
Department of Physics, University of California, Santa Barbara, CA
93106, USA.
*
To whom correspondence should be addressed. E-mail:
peale{at}io.physics.ucsb.edu