A COMET that appeared in the night sky over Christmas has invited comparisons with the Star of Bethlehem. But it is amateur astronomers with telescopes and binoculars who are pursuing the object rather than Wise Men bearing gifts. Comet Machholz will be at its most visible tomorrow and Thursday. Even then it will be no more than a faint smudge of light difficult to see with the naked eye. A pair of binoculars pointing south should pick it out near the Pleiades star cluster. Comets have been proposed as an explanation for the star that guided the Three Wise Men...