Rudolph the red-nosed reindeer
Rudolph needs lots of carbs to replace the energy lost from his bright noseSteve Zmina/iStock

Research has shown exactly why Father Christmas relies on Rudolph the Red-Nosed Reindeer to guide him, and the other seven reindeer, to their destinations. Apparently his bright red nose uses so much energy that he relies on lots of high-calorie foods to get him through the Christmas Eve rush.

Unlike humans and most other mammals, studies have shown that Arctic reindeer can use ultraviolet light to guide them. When the sun goes down on Christmas Eve, this means that Father Christmas's reindeer are perfect for 'driving', as the night sky will not affect their navigation.

It was also found that these reindeer experience an incredible change of colour in their eyes in the winter. In the summer time, the reflective tissue appears a full golden colour, but during winter the colour changes to a dark blue. It is this dark blue colour that is found in nocturnal animals to help them see in the dark – another benefit to Rudolph and his friends.

However, the scientific element which makes Rudolph stand out from the rest of the reindeer is his ability to navigate through fog. The blue reflective tissue doesn't account for flying through fog at night, but research has shown Rudolph's bright red nose would be the perfect solution for a fog light – allowing the other reindeer to follow the red light.

Nathaniel Dominy, professor of anthropology at Dartmouth University, used red holly berries to estimate the colour of light emitted from Rudolph's bright red nose. He measured the colour of the berries, and then concluded that the brightness of his nose is equal to the maximum level of colour that mammals can see.

Rudolph the red-nosed reindeer
Rudolph's bright red nose acts as a fog light to guide the way for Father ChristmasTristan Ferne/Flickr

Dominy did suggest, however, that the brightness of the red nose would get extremely hot, and the poor guy would lose a lot of energy just by guiding the way. He did have a solution though, as he writes: "It is therefore imperative for children to provide high-calorie foods to help Rudolph replenish his energetic reserves on Christmas Eve."

The research by Nathaniel Dominy uses Arctic reindeer to illustrate the science of Rudolph. The bright-nosed reindeer was too busy for the investigation, as he was getting prepared for Christmas night.