No, there's no proof of a giant planet in the outer solar system
The entire universe in blog form Feb. 14 2011 2:30 PM   I'm
getting a lot of email and tweets about NASA supposedly having
proof of a giant, Jupiter-sized planet orbiting the Sun way
beyond Pluto. Let me be clear: while certainly possible, this
idea is not at all proven, and in my opinion still pretty
unlikely. As usual, this started as a more-or-less accurate
media story and is getting inflated as it gets re-reported. As
far as I can tell, the original report was in the UK paper The
Independent.  Here's the deal. Two astronomers, John Matese and
Dan Whitmire, have theorized about the possibility of a
previously-undiscovered planet way beyond Pluto for some time.
This is not a crazy idea; we see planets orbiting other stars
way out, and there's other evidence big planets can be pretty
far out from the Sun (mind you, evidence does not mean proof).
As it happens, there are lots of chunks of ice orbiting the Sun
pretty far out as well. Some of the