Siteadmin, Check users, Administrators
12,071
edits
Changes
→Resonating orbits
The origin of the resonance itself is controversial. Peale and Lee, in 2002, presented a model suggesting that this resonance is primordial and thus was part of the Jovian system since its formation.<ref name=Peale>Peale, S. J., and Lee, Man Hoi. "[http://adsabs.harvard.edu/abs/2002Sci...298..593P A Primordial Origin of the Laplace Relation Among the Galilean Satellites]." ''Science'', 298(5593):593-597, October 2002. Accessed February 18, 2008.</ref> Their model, however, derives from the [[nebular hypothesis]] of the formation of the solar system and thus depends on [[uniformitarianism|uniformitarian]] assumptions. Showman and Malhotra suggest a model by which the resonance developed after the solar system had formed.<ref name=Showman/>
The origin of the resonance itself is controversial. Peale and Lee, in 2002, presented a model suggesting that this resonance is primordial and thus was part of the Jovian system since its formation.<ref name=Peale>Peale, S. J., and Lee, Man Hoi. "[http://adsabs.harvard.edu/abs/2002Sci...298..593P A Primordial Origin of the Laplace Relation Among the Galilean Satellites]." ''Science'', 298(5593):593-597, October 2002. Accessed February 18, 2008.</ref> Their model, however, derives from the [[nebular hypothesis]] of the formation of the solar system and thus depends on [[uniformitarianism|uniformitarian]] assumptions. Showman and Malhotra suggest a model by which the resonance developed after the solar system had formed.<ref name=Showman/>
== Interiors ==
[[Image:Galilean moons interiors.jpg|thumb|300px|left|Cutaway views of the interiors of [[Io]], [[Europa]], [[Ganymede]], and [[Callisto]]]]The recently completed [[Galileo Project]] has returned a wealth of data that has allowed planetary scientists to refine greatly their models of the interiors of the Galilean moons. Their best conjectures of those interior structures are shown at the left.
Except for Callisto, all the moons appear to have metallic (iron, nickel) cores. Again, except for Callisto, all the cores are surrounded by rock shells. Io's rock or silicate shell extends to the surface, while the rock layers of Ganymede and Europa are in turn surrounded by shells of water in ice or liquid form. Callisto is shown as a relatively uniform mixture of comparable amounts of ice and rock. Recent data, however, suggests a more complex core than has been previously supposed.
The surface layers of Ganymede and Callisto may differ from the underlying ice/rock layers in a variety of ways, including the portion of rock they contain. Europa's surface could be similarly composed, or it could have an ice surface overlying a liquid water ocean. Galileo images of Europa suggest that a liquid water ocean might now underlie a surface ice layer seven to ten kilometers thick.<ref>"[http://photojournal.jpl.nasa.gov/catalog/PIA01082 Catalog page for Image PIA01082]," ''NASA/JPL Photojournal''. Accessed February 29, 2008.</ref>
== Io ==
== Io ==