Comet C/2013 A1, also known as Siding Spring, approached its close encounter with Mars on October 19. The comet was expected to pass within about 87,000 miles of Mars at 2:27 p.m. EDT (GMT-4) at a relative velocity 126,000 mph.
Siding Spring, which was discovered in January 2013, comes from the Oort Cloud, a vast halo of comets and potential comets. The Oort Cloud extends from well beyond the orbit of Pluto halfway to the nearest star, so far comets like Siding Spring need a million years or more to make the long plunge in...
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