WASP-13b
... that planet WASP-13b, despite a radius 25% larger than Jupiter's, has less than half the mass?
... that planet <b id="mwDco"><a href="./WASP-13b" id="mwDcs" rel="mw:WikiLink" title="WASP-13b">WASP-13b</a></b>, despite a radius 25% larger than <a href="./Jupiter" id="mwDcw" rel="mw:WikiLink" title="Jupiter">Jupiter</a>'s, has less than half the mass?