National Geographic reports C/2012 S1 is expected to pass at about 6.2 million miles/10 million kilometers (0.07 AU (10,000,000 km; 6,500,000 mi) from Mars on October 1, 2013. This will allow NASA's Curiosity rover on Mars opportunity to snap pictures.
Astronomers at the Remanzacco Observatory, Italy have assured that the comet is not on collision course with Earth. They say C/2012 S1 "will get to within 0.012AU of the Sun at the end of November 2013 and then to ~0.4AU (about 37 million miles) from Earth at the beginning of January 2014."
October 05, 2012
Big Comet Coming
It is supposed to be a bright one: