Comet ISON Swings by Mars
Location of Comet ISON on October 1, 2013. Courtesy Astronomy Outreach Network & Sky's Up Magazine
On October 1st, Comet ISON will make its closest approach to Mars. It will fly by the Red Planet at a distance of 6.7 million miles, and several instruments will be ready to gather information on the encounter. Both Curiosity and Opportunity will be watching from the planet's surface, and NASA will also attempt to detect ISON with the HiRISE camera aboard the Mars Reconnaissance Orbiter, or MRO. HiRISE is normally used to photograph small (1 meter) well-lit features on the Martian surface, and so it is difficult to say whether Comet ISON will be detected, however it is good practice for a much closer encounter between Mars and an inbound comet in October of 2014. According to calculations by NASA, Comet Siding Spring (C/2013 A1) will come to within 68,000 miles of Mars on October 19th, 2014. That is very close indeed, and while the chance that Comet Siding Spring will hit Mars is 120,000 to 1, the encounter should be spectacular.
The above graphic was borrowed from the summer edition of Sky's Up, a free quarterly magazine produced by The Astronomy Outreach Network for anyone interested in the night sky. Visit the Network's website for graphics depicting the location of Comet ISON through mid-January, 2014, and for links to read and/or download Sky's Up.