We had to send our space traveller, Pierre Kerr, to each planet to check out your question. That's why it took so long!

It's diffcult to say for sure, since no exploration of planets has included drilling down to the centre. However, by calculating the density of a planet and knowing what the surface is composed of, scientists can make predications of what the interior may be composed of.

The terrestrial planets, Mearcury, Venus, Earth Mars and Pluto are believed to have a dense metallic, mostly iron and nickel centres. The Jovian planets, Saturn, Jupiter, Uranus and Neptune are mostly composed of hydrogen. Since Saturn and Jupiter are so large and their centres so dense, it is probably made of solid hydrogen.

Answer #% % filename IO.DOT page% % page 1 of% % numpages 1 % % date \@ "MMMM d, yyyy"June 26, 1995