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:Shenzhou 11: China’s manned space mission – Latest updates, tracking, pathHunter’s Moon 2016: Where, when and how to watch the full blood Moon tonightDiver Recounts His Encounter With a Cage-Breaking Great White SharkNations, Fighting Powerful Refrigerant That Warms Planet, Reach Landmark DealTrilobites: Can This Caterpillar Predict Winter Weather? Probably Not Very WellChina Astronauts to Attempt Nation’s Longest Space Mission