Alternating planetary phase layers

[Loren Booda]

Terrestrial planets in general are solid, or solid with a liquid core. Gaseous planets in general are liquid, or liquid with a solid core.

Can there be planetoids with substantial alternating layers of solid - liquid - solid, or liquid - solid - liquid? (I do not consider Earth's hydrosphere as substantial in this regard.) I believe there are some known moons which qualify.

[ohwilleke]

As I understand it, the Earth has a gaseous atmosphere, over much of its expanse, a liquid ocean, a solid crust, liquid rock pockets, a solid layer, a liquid layer, and a solid metal core.

The earth is made of four layers. We live on the earth’s crust made of rocks broken into small pieces. The continents, ocean floors, mountains, and valleys of the earth’s surface are in the earth’s crust. Below the crust there are pockets of melted rock. Under the melted rock is the mantle. The mantle is made of solid hot rock with temperatures from 900 to 3000 degrees Celsius. The outer core is the third layer. It is liquid metal melted from temperatures between 3000 and 4000 degrees Celsius. The inner core at the center of the earth is solid metal and the temperature is between 3000 and 6500 degrees Celsius.


http://volcano.und.nodak.edu/vwdocs/kids/volcano_project/volcanoes.html

I see no reason why this couldn't happen elsewhere.

[Nereid]

Europa (certainly), Ganymede (almost certainly), and Callisto (maybe) are all at least solid-liquid-solid.

The state which matter is in depends (at least) on its composition (mix of compounds), temperature, and pressure; with a huge set of inputs of the physical properties (e.g. phase diagrams) of a great many compounds, the appropriate geophysical equations (for determining equilibrium conditions), and a lot of patience you could have a lot of fun making all kinds of strange planets! Oh, and making sure you get all the chemistry right too will earn you extra gold stars!