Mysterious ‘Planet Nine’ could be an alien exoplanet stolen by our sun 4.5 billion years ago Prison Planet.com Posted on June 1, 2016 Posted in Aggregated No Comments Tagged with Sci Tech Daily Mail | It has been one of the biggest mysteries in astronomy – does planet nine exist, and what is it? Share this:Share Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Share on LinkedIn (Opens in new window) LinkedIn Email a link to a friend (Opens in new window) Email