A newfound comet is apparently on course to have an exceedingly close call with the planet Mars in October 2014, and there is a chance — albeit small — that the comet may even collide with the Red Planet.
The new comet C/2013 A1 (Siding Spring) was discovered Jan. 3 by the Scottish-Australian astronomer Robert H. McNaught, a prolific observer of both comets and asteroids who has 74 comet discoveries to his name.
McNaught is a participant in the Siding Spring Survey a program that hunts down asteroids that might closely approach the Earth. He discovered the new comet using the 0.5-meter Uppsala Schmidt Telescope at Siding Spring Observatory, New South Wales, Australia.
Pre-discovery images of the comet from Dec. 8, 2012 by the Catalina Sky Survey in Arizona were quickly found. Because the comet was discovered as part of its survey for asteroids, it bears the name of the observatory, Siding Spring. Officially it is catalogued as C/2013 A1.
When it was discovered, Comet Siding Spring was 669 million miles (1.07 billion kilometers) from the sun. Based on its orbital eccentricity, it is apparently a new or "virgin" comet, traveling in a parabolic orbit and making its very first visit to the vicinity of the sun. It is expected to pass closest to the sun (called perihelion) on Oct. 25, 2014 at a distance of 130 million miles (209 million km).
But, less than a week earlier, on Oct. 19, 2014, the comet — whose nucleus is estimated to be anywhere from 5 to 30 miles (8 to 50 km) in diameter — is projected to cross the orbit of Mars and pass very close to that planet. Preliminary calculations suggest that nominally at closest approach, Comet Siding Spring will come to within 63,000 miles (101,000 km) of Mars.
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