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This is a drawing of the evolution of the interior of an icy moon.
Click on image for full size
Image from: The New Solar System

How the Interior of Icy Moons Formed

The drawing shows how the inside of an icy moon comes together. As the moons drew material from the nebula around them, bits of heavy rock gathered inside the forming moon, as illustrated in figure A.

Once the moon finished forming, these heavy, solid bits of rock fell into the center, as illustrated in figure B. Eventually, the rock at the center solidified into a core, as illustrated in figure C.

The ice on the outside of the core gradually changed from warm, slushy ice, shown in purple in figure B, to completely frozen ice, as shown in figure C.


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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA