Week 2: Planet X

As probably everyone who is remotely interested in astronomy has heard, a new planet was recently discovered. What's notable about this planet is that it orbits our own Sun, which makes it a candidate for inclusion in The Official Planet Roster Of Our Solar System--a list from which Pluto was crossed off in 2006.

While Planet X (whose name for some reason just reminds me of Chemical X from the Powerpuff Girls) has been detected due to its gravitational effects on other objects in our solar system, including the minor planet Sedna, it hasn't been visually detected. Part of the reason for this is because of how far away it is. Estimates for its closest approach are around 200 AU--almost 7 times that of Neptune, the most distal planet in our solar system (since Pluto's demotion at least)--and its farthest distance could be as large as 1,200 AU. At that distance, it would take light from the Sun almost a week to reach the planet. This makes it pretty difficult to find with a telescope.

In an ironic twist, one of the scientists who published results supporting the existence of Planet X was Mike Brown, a Caltech scientist whose previous work directly led to Pluto's demotion. On discovering Planet X, he said, "Killing Pluto was fun, but this is head and shoulders above everything else." Harsh.

Sources: 
https://www.centralmaine.com/2016/01/27/the-discovery-of-planet-x/
http://ih0.redbubble.net/image.77569687.6291/raf,220x200,075,f,black.u5.jpg
https://en.wikipedia.org/wiki/Pluto
https://en.wikipedia.org/wiki/90377_Sedna
http://www.sciencemag.org/news/2016/01/feature-astronomers-say-neptune-sized-planet-lurks-unseen-solar-system
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEim9temp3WPCmNNxpr03SbtAAKjeBqRM6ZpyowVuvYbQtxMNYOsXCcvExzwsHez5aPwTM_fhOsjAQ1ntIIVV9SgRLKBPnRRfmYVF6P7_FzefLwGhGpxMVaImToYCHMhl6sUErQ3MsEfNv81/s1600/sad+pluto4.jpg