Russian scientist spies mountain-sized asteroid heading our way, Dec 2014, UFO Sighting News.

Asteroid name: 2014 UR116
Scientist name: Vladimir Lipunov, a professor at Moscow State University
Date of announcement: December 2014
Source: http://news.yahoo.com/russian-scientist-spies-mountain-sized-asteroid-heading-way-170022867.html

Yahoo news states:

In the film, Lipunov says it's difficult to calculate the orbit of big objects like 2014 UR116 because, as they hurtle through the solar system, their trajectories are constantly being altered by the gravitational pull of nearby planets. "We need to permanently track this asteroid, because even a small mistake in calculations could have serious consequences," he said. 

There is little indication that this particular asteroid could hit the Earth in the next few decades, though over a much longer period a collision looks quite likely, says Natan Esmant, an expert with the official Space Research Institute in Moscow. A more serious issue, he says, is the estimated 100,000 near-Earth objects, such as asteroids and comets, which can cross our planet's orbit and are large enough to be dangerous. Only about 11,000 have so far been tracked and cataloged. (More at source).