Rotation of Europa: Constraints from Terminator and Limb Positions

Gregory Hoppa, Richard Greenberg, Paul Geissler, B. Randall Tufts, J. Plassmann, Daniel D. Durda

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Tidal torques on Europa due to Jupiter would tend to drive Europa's rotation to a rate slightly faster than synchronous, unless synchroneity is maintained by a permanent asymmetry in Europa's mass distribution. Moreover, global fracture patterns on Europa's surface, as well as the complex fine-scale tectonics revealed by Galileo high-resolution imagery, may be evidence of stress due to nonsynchronous rotation. A direct measurement of Europa's rotation rate is made from the positions of surface features relative to the terminator in a Galileo image and comparing the results with similar measurements of the positions of the same features relative to the terminator in a Voyager 2 image taken 17 years earlier. Any nonsynchronous rotation must be slower than a few tenths of a degree in 17 years (a complete rotation in >104years) relative to the direction of Jupiter.

Original languageEnglish (US)
Pages (from-to)341-347
Number of pages7
Issue number2
StatePublished - Feb 1 1999


  • Europa
  • Rotation
  • Satellites of Jupiter

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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