giant planet
... that in 1999, a giant planet was hypothesized to exist in the outer Oort cloud of the solar system, but most astronomers are skeptical of its existence?
... that in 1999, a <b id="mwBrI"><a class="mw-redirect" href="./Tyche_(planet)" id="mwBrM" rel="mw:WikiLink" title="Tyche (planet)">giant planet</a></b> was hypothesized to exist in the outer <a href="./Oort_cloud" id="mwBrQ" rel="mw:WikiLink" title="Oort cloud">Oort cloud</a> of the <a class="mw-redirect" href="./Solar_system" id="mwBrU" rel="mw:WikiLink" title="Solar system">solar system</a>, but most astronomers are skeptical of its existence?