Planet Nine discovery: What is Planet 9? Is Planet X in our solar system? PLANET Nine, aka Planet X, has perplexed astronomers since it was first proposed in 2014. So what exactly is Planet X and is Planet 9 in our solar system? Share: Facebook Twitter Google+ Stumble Digg Email ThisBlogThis!Share to XShare to Facebook Related Posts:Op-Ed Contributors: What Trump’s Budget Means for the Filet-O-FishWatching Their Dust: Photographing Players in PollinationSUPERHUMANS: Mars 'will be colonised by genetically engineered Star Trek-style beings'That Ghostly, Glowing Light Above Canada? It’s Just SteveBasics: As Rains Ease in the West, Cacti Shine Brighter Than EverSHOCK DISCOVERY: Giant dinosaur eggs found INTACT - & they are 70 MILLION years old