The Mars-grazing comet is called C/2013 A1, but you can call it Comet Siding Spring for short. Siding Spring is the name of the Australian observatory from which it was first spotted.

Comet C/2013 A1, discovered last year at the Siding Spring observatory in Australia, 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.

Comet brightness is difficult to predict. Although it's been clear enough for binoculars so far, it's possible that a telescope will be necessary to see Comet ZTF by the time it lines up with Mars.

Comet Siding Spring was named for the Australian observatory that first detected it in early 2013 and is currently expected to pass within 87,000 miles (139,500 kilometers) of Mars on Sunday ...

Comet C/2013 A1 (Siding Spring) will pass extremely close to Mars on Oct. 19, 2014. There is even a small possibility that it could impact the planet, although new tracking data has minimized this ...

A speeding comet the size of a mountain will come within 87,000 miles of Mars on Oct. 19, and NASA is planning to observe it with just about everything the agency's got.

Astronomers are meticulously tracking the new interstellar visitor that is crossing our solar system. Officially designated ...

One of Earth's closest neighbors is about to have a very narrow escape. A comet the size of a small mountain will whiz past Mars Sunday at a distance of less than 87,000 miles, a hair's breadth in ...

NASA's Mars Exploration Rover Opportunity made this 10-second-exposure view of comet C/2013 A1 Siding Spring, as it flew past Mars on Oct. 19, 2014. Read the full story .

The latest orbital plot places the comet's closest approach to Mars a little farther out than previously estimated -- at about 73,000 miles (117,000 kilometers) from the surface of the Red Planet.