Why is it believed that warm dense matter exists at the core of some planets?

1 Answer
Jun 22, 2016

Planets' interiors are deduced from models based on observation.


We can't see directly what the internal structure of a planet is unless we can send a probe inside it.
We can determine the mass of a planet by observing the orbit of a moon.
We can measure how far away a planet is from its orbit.
This means we can calculate its size from the angular diameter of its disc and the distance away.
From the mass and size we can determine its density.
We can determine the composition of its atmosphere by spectroscopic analysis.

Given this information we know that the planets Uranus and Neptune consist of hydrogen and helium and ices. Ices are the technical term for compounds such as water, ammonia and methane. So, technically these are ice giants not gas giants.

These ices are not like familiar water ice. In the core of an ice giant the temperatures and pressures will be high. They will be warm dense liquids.