Can reindeer fly? Why is Santa Claus fat? Could scientists clone the perfect Christmas tree? Was the star of Bethlehem really a comet? Why is Rudolph's nose red? How does Santa manage to deliver presents to an estimated 842 million households in a single night? What could we do to guarantee a white Christmas every year? These are among the questions explored in an irresistibly witty book that illuminates the cherished rituals, legends, and icons of Christmas from a unique and fascinating perspective: science.