New observations of comet C/2013 A1 (Siding Spring) have allowed NASA’s Near-Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif. to further refine the comet’s orbit.
Based on data through April 7, 2013, the latest orbital plot places the comet’s closest approach to Mars slightly closer than previous estimates, at about 68,000 miles (110,000 kilometers). At the same time, the new data set now significantly reduces the probability the comet will impact the Red Planet, from about 1 in 8,000 to about 1 in 120,000. The latest estimated time for close approach to Mars is about 11:51 a.m. PDT (18:51 UTC) on Oct. 19, 2014. At the time of closest approach, the comet will be on the sunward side of the planet.
Future observations of the comet are expected to refine the orbit further.