Physiologist Paolo Viscardi estimates that reindeer would need a 33-foot-long wing span in order to take flight.

Courtesy University of Leeds

Now Dasher! Now Dancer! Now Prancer and Vixen!

Sleighs are large sleds or carriages used for transportation in colder climates -- they have two runners on the bottom instead of wheels, making it easier to barrel across snow and ice. With the aid of kinetic energy, a sleigh can easily travel downhill. But once it plateaus, it needs momentum to keep moving and navigate any steep terrain -- or in Santa's case, take flight. But what if the Stardust Antimatter Propulsion Unit malfunctions? Enter plan B: reindeer, the engines behind the sleigh.

What we know about these majestic creatures -- aside from their steady diet of carrots -- is that these particular reindeer would need wings to properly fly. Paolo Viscardi, a flight physiologist from the University of Leeds, suggests that Santa's reindeer would need a 33-foot-long wingspan in order take flight, and a sizeable team of reindeer would be required to lift Santa's sleigh [source: The Guardian]. An extra source of heat from the hot cocoa maker in the dashboard would send out hot air, acting like a thermal unit in a hot air balloon, giving the reindeer an extra lift that Viscardi recommends for optimal flying conditions.

According to the famous poem "A Visit from St. Nicholas" by Clement Clarke Moore -- and the disgruntled elf -- a team of reindeer drive Santa's sleigh. These are the reindeer we know of: Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner/Donder, Blitzen and Rudolph.

A reindeer training with a virtual reality flight simulator

2007 HowStuffWorks

Of course, the most widely recognized reindeer is Rudolph. Folklore has it that during a particularly foggy Christmas Eve one year, Santa was unable to fly his sleigh due to poor visibility. We've posited that Rudolph helped guide Santa's sleigh through the bad weather with his bioluminescent nose radiating a red light. (Learn more about why Rudolph's nose is red.)

In the next section, we'll look at the possibility of a secret training facility in the North Pole, where reindeer get ready for the big day.