The chance that a rogue mini-world - asteroid 2007 WD5 - will smack into Mars on January 30th has increased from 1.3 percent to 3.9 percent.

That's the new estimation from officials at the Near Earth Object Program at the Jet Propulsion Laboratory (JPL), stemming from several sky watching teams in Alaska, New Mexico, and in Arizona.

"The impact probability resulting from the recent orbit refinement has increased to a surprising 3.9 percent...about 1 in 25 odds," explain JPL's Near Earth Object Program website, updated today regarding the asteroid meets Mars altercation.

Still, there remains an uncertainty, although a Mars impact is still possible. However, the most likely scenario in the weeks to come is that more observations of the asteroid will allow that uncertainty to shrink - so that a Mars impact is definitely ruled out.

The JPL website notes that, in the unlikely event of an impact, the head-on collision would take place on January 30th at 2:55 a.m. Pacific Standard Time, with an uncertainty of a few minutes.

Nothing to set your watch by...but a big event in our time.