Date: 1993 - 1999
On the core of Uranus what is in the water content?
The astronomy texts I looked at seem to agree that the core of Uranus
is composed of a mixture of ice and rock, the core having a radius of
approximately 1/3 of Uranus' radius. One text estimates that the cores
of the gas giants are roughly half water ice and half rock. This guess
is based on trying to match the observed planet densities using estimates
for water-ice density and a "typical" rock density at the pressures
believed to exist in the interiors. However, there was an article
in the March 1992 issue of Sky & Telescope magazine that questioned
the presence of rocky material. The following is an abstract of that
article, provided by the online Reader's Guide Abstract Index:
"Data from Voyager 2 and recent laboratory experiments suggest that Uranus
and Neptune may have highly pressurized slushy interiors rather than the
rocky cores predicted by standard models of planet formation. William B.
Hubbard of the University of Arizona and colleagues mixed water, ammonia,
and isopropanol to create a material similar to the mantle of Uranus, then
subjected the mixture to pressures of 2 million atmospheres. They report
in the August 9, 1991, issue of Science that the characteristics of the
compressed liquid matched models of Uranus and Neptune's interiors so well
that rocky cores became superfluous."
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Update: June 2012