Just discovered January 3rd, 2013, there is a finite probability of a collision of a large Oort cloud object with Mars on October 19, 2014. It's coming through the orbital plane from a steeper angle than Pluto, but looks as though it will come surprisingly close (or possibly hit) Mars. The object size is unknown at this point, but estimates place the size anywhere from perhaps as little as 10km to as much as
50km in diameter. (Absolute magnitude is 10.3.) In short -- big. Because it is retrograde, the estimated approach velocity to Mars is significant -- perhaps more than 56 km/s.Interesting reports on current orbital elements as they develop are found below The first link is the initial announcement and the 2nd link was updated today with new observations and a refined set of elements. The original estimate put it to a distance of 703 microAU from Mars' surface. Today's estimate adjusts this to about 249 microAU from Mars' surface.
Decent orbital simulation using earlier orbital parameters follows:
You can change your perspectives on it, which is nice. That simulation places it about 703 microAU from Mars, per the earlier orbital elements.
Worth a look.
A blog on the topic:
Jon