Mark your calendar now for December 2013 comet-viewing party

Provided that the world does not end in December of 2012, you might have the opportunity to view a particularly impressive comet around Christmastime in 2013. The poetically named C/2012 S1 (ISON) will pass at a-safe-yet-great-for-viewing distance from Earth, after first passing close to the Sun — a combination that promises to produce a beautiful tail and fabulous comet-spotting opportunities, especially in the Northern Hemisphere. Maggie