New Calculations Effectively Rule Out Comet Impacting Mars in 2014. NASA’s Near-Earth Object Office says that new observations of comet C/2013 A1 (Siding Spring) have allowed further refinements of the comet’s orbit, helping to determine the chances it could hit Mars in October of 2014.
Leonid Elenin, Russian comet hunter and discoverer of the famed Comet C/2010 X1 Elenin, has examined C/2013 A1’s orbit and found there’s a small chance it could collide with the planet Mars on October 19 next year.
Based on 74 days of observations plus the latest data from Elenin, which admittedly only cover a short piece of the comet’s arc, A1 could zoom as close as 22,990 miles (37,000 km) from the surface of Mars and shine 40 times brighter than Venus at magnitude -8.5 as seen from Mars that is.
C/2013 A1 turns out to be a potentially BIG comet with a diameter estimated at up to 31 miles (50 km) across.