How To Watch That Once In A Lifetime Comet Swing By Mars

A comet will be swinging by Mars this Sunday, and eager astronomers say they're ready for the "once-in a lifetime event."

Comet C/2013 A1, or 'Siding Spring' will make its closest approach to Mars at 2:27 p.m. EDT, coming within 87,000 miles of the red planet's surface. That's 16 times closer than any comet has ever come near Earth and less than half the distance from Earth to the moon.

"This is a cosmic science gift that could potentially keep on giving, and the agency's diverse science missions will be in full receive mode," John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington, D.C., said in a written statement. "This particular comet has never before entered the inner solar system, so it will provide a fresh source of clues to our solar system's earliest days."

NASA will be tracking the spectacular flyby with a massive fleet of spacecraft and Earth-based telescopes.