astroengine writes "According to preliminary orbital prediction models, comet C/2013 A1 will buzz Mars on Oct. 19, 2014. C/2013 A1 was discovered by ace comet-hunter Robert McNaught at the Siding Spring Observatory in New South Wales, Australia, on Jan. 3. When the discovery was made, astronomers at the Catalina Sky Survey in Arizona looked back over their observations to find "prerecovery" images of the comet dating back to Dec. 8, 2012. These observations placed the orbital trajectory of comet C/2013 A1 through Mars orbit on Oct. 19, 2014. Due to uncertainties in the observations — the comet has only been observed for 74 days (so far), so it's difficult for astronomers to forecast the comet's precise location in 20 months time — comet C/2013 A1 may fly past at a very safe distance of 0.008 AU (650,000 miles). But to the other extreme, its orbital pass could put Mars directly in its path."