2016-01-20. Evidence suggests huge ninth planet exists past Pluto at solar system's edge.

posted Jan 21, 2016, 1:33 PM by Alan Gould   [ updated Jan 21, 2016, 1:54 PM ]
By Ian Sample, The Guardian. For GSS A Changing Cosmos chapter 7. Excerpt: Astronomers investigating the odd alignment of rocks beyond Pluto have concluded that an undetected icy planet four times the size of Earth must exist. ...If the researchers have their sums right, the mysterious new world is 10 times more massive than Earth and up to four times the size. Nicknamed Planet Nine, it moves on an extremely elongated orbit, and takes a staggering 10,000 to 20,000 years to swing once around the sun. ...Scientists at the California Institute of Technology (Caltech) calculate that the closest it comes to the sun is 15 times the distance to Pluto. It then heads into uncharted territory, 75 times further out than Pluto, or about 93 billion miles from the sun. A ray of light would take a week to get there. ...Chris Lintott... said ...“One very interesting thing is that the planet is predicted to be between Earth and Neptune in mass. We see lots of planets this size in our surveys of planets elsewhere in the galaxy, and it’s been something of a mystery as to why our solar system doesn’t have its own version of this very common planet type,” he added.....  http://www.theguardian.com/science/2016/jan/20/ninth-planet-solar-system-edge-discovery-pluto  See also New York Times article.