Pluto's 'almost twin' dwarf planet Eris has a rocky core blanketed by an icy shell, which appears to be flexing slowly.

Twenty-five years ago, when he began his Pluto quest, planetary scientists were still anticipating the conclusion of the Grand Tour of the outer solar system by the twin Voyager spacecraft ...

Pluto's 'almost twin' dwarf planet Eris has a rocky core blanketed by an icy shell, which appears to be flexing slowly.