Abstract
Recent observations from NASA's Galileo spacecraft reveal that Callisto, one of Jupiter's sixteen moons, is like an undifferentiated “dirty snowball” that has no internal magnetic field or magnetosphere. The outermost of the four large moons discovered by Galileo may be enshrouded by a tenuous atmosphere, however. The new findings, reported in the latest issue of Nature, are surprising because earlier data from Galileo indicates that two of Jupiter's other Galilean moons—Ganymede and Io—have magnetic fields. John D. Anderson of the Jet Propulsion Laboratory in Pasadena, Calif., and colleagues presented gravimetric data showing that Callisto is composed of 40% compressed ice and 60% rock mixed with metal. The undifferentiated composition is consistent with the absence of a magnetic field, which was confirmed by Krishan Khurana of the University of California and his colleagues.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
