ArrayIndexOutOfBound writes "The newly found planet Sedna may have a moon. It appears that most astronomers argue that Sedna is only another proof that neither Sedna nor Pluto are really planets.
Interestingly, the planet has been found by an 'automated sky survey telescope'..."
points to a NASA page with more information about "our potential 10th planet. ... It is 130 billion miles away from the sun (900 times Earth's distance from the sun) and has a 10,500 years orbit, compared to Pluto's 230 years around the sun."